261 results
Blank
PROJECT NUMBER • 2016-204
PROJECT STATUS:
COMPLETED

Indigenous business development opportunities and impediments in the fishing and seafood industry - 'Wave to plate' establishing a market for Tasmanian cultural fisheries

The FRDC project, ‘Wave to Plate’: establishing a market for cultural fisheries in Tasmania, is the first time that an Aboriginal Tasmanian postdoctoral researcher has engaged with marine research in Tasmania. Indigenous-led research has delivered a raft of outcomes that can be...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Workforce
Rac Tas
Publication
Policy
Marketing

Phase 2: Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market

Project number: 2016-177
Project Status:
Completed
Budget expenditure: $265,000.00
Principal Investigator: Laurie B. Bonney
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 May 2017 - 16 Jul 2019
Contact:
FRDC
TAGS
Wild Catch
Traceability
Market Opportunities
Labelling
Food Safety
SPECIES
Southern Rock Lobster

Need

The need for traceability was first prioritised in strategic planning by SRL because of a bloom in harmful algae (HABs). These events in 2013 occurred during a closed season but highlighted the vulnerability of the industry to the lack of traceability - a bloom in the open season and subsequent recall would have led to all. Australian product being recalled, not just lobsters from affected areas. The impact would have been catastrophic. The need is now recognised to be wider than HABs and includes risk management options for food safety incidents beyond toxic algal blooms, compliance with changes to requirements of importing countries, business-to-business and business-to-consumer verification of food safety, quality, and sustainability credentials. Traceability also enables the industry to look back at harvesting operations - what locations and practices led to the best product delivered to consumers?

Seafood is the most highly traded food commodity globally, and yet there is very little traceability in any seafood supply chain, or country of origin labelling at the point of market, including those used for live Australian Southern Rock Lobster (ASRL). A successful project will lead the seafood industry in traceability, providing a lead for other seafood industries. Improved technical traceability may also open up new markets such as the European Union - currently no SRL operators are accredited for lobster export to the EU.

The main need at present is the Chinese market by the introduction of a tagging/traceability system to clearly identify and differentiate ASRL in the China market from other imported lobster. Indeed, actions to address traceability forms part of the first priority issue within Objective 1 (“Add value along the supply chain from fisher to customer”) within SRL’s SRL’s Strategy 2022, and previously Strategic Plan 2011-16. These type of requirements are increasingly being applied for traded food and are evolving. A traceability system for ASRL would also facilitate compliance with the Global Seafood Sustainability Initiative (GSSI) emerging.

Objectives

1. Traceability/sensor technologies integrated in chains
2. Traceability system validated
3. Traceability system value proposition(s) determined.

Final report

ISBN: 978-0-646-81652-4
Authors: Laurie Bonney Luke Mirowski Ryan Day Mikaela Seabourne Shayden vanWinden Sumit Verma Son Anh Vo Caleb Gardner Paul Turner
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 
Final Report • 2020-09-08 • 5.81 MB
2016-177-DLD.pdf

Summary

This document is the final report of the project (FRDC 2016-177) ‘Traceability Systems for Wild Caught Lobsters’. It has been prepared by researchers from University of Tasmania.
 
Background
The project ‘Traceability Systems for Wild Caught Lobster, via Sense-T and Pathways to Market’ aims to contribute to improving traceability and product provenance within the wild caught Southern Rock Lobster supply chain. The project was divided into two phases:
  • Phase One: a multidisciplinary scoping phase previously completed (FRDC 2016-228) and,
  • Phase Two: a system design and trial evaluation phase that is the focus of this final report (FRDC 2016-177)
The overall project arises from changes to international and national settings relevant to the SRL industry. In particular, the China Free Trade Agreement (ChAFTA) is a key driver, as changes in the Chinese market will continue to impact on the way lobster are traded to China into the future. In designing the overall project, the research team considered earlier FRDC/ASCRC (Australian Seafood Cooperative Research Centre) project reports and these included: 2012/704, 2012/705, 2012/741, 2010/716, CRC Supply Chain Technology Report. Other project reports the team were aware of prior to conducting this research proposal included: 2012/702, 2011/748, 2012/703, 2008/790, 2007/700, 2007/708.
 
Methodology
Using the framework developed in Phase One (FRDC 2016-228), Phase Two was designed to accommodate differential levels of existing traceability amongst businesses of different sizes along the rock lobster supply chain. As a consequence, the investigation and enhancement of traceability was conducted at three different levels reflecting differential needs/capacity of industry participants:
  • Batch level;
  • Batch level with individual tagging;
  • Item level with individual tagging.
These different levels of traceability were then investigated and implemented using a variety of systems and technologies in six work programs structured as follows:
  • WP1 - Batch Level Traceability (boat/truck/processor)
  • WP2 - Batch Level Traceability with Individual Tagging (processor)
  • WP3 - Batch Level Traceability with Individual Tagging (boat)
  • WP4 - Batch Level Traceability with Individual Tagging (processor/overseas processor)
  • WP5 - Item Level traceability with individual tagging (boat/truck/processor)
  • WP6 - Item Level traceability with individual tagging (processor/overseas processor)
Results and Outputs
Through engagement with the industry the team have developed a tailored approach to SRL traceability systems supported by policies and procedures, data models and a series of benchmarking checklists.
 
The research has also produced several digital tools and techniques that have been deployed as part of the trial and evaluation work conducted with industry. These trials and their evaluation are presented as a series of case studies presented throughout this section of the report. The case studies provide standards and practical advice on how to implement and achieve defined levels of traceability. This work is based on the globally recognised GSM1 standards and was customised for the SRL industry through survey and engagement with the industry across South Australia, Tasmania and Victoria.
 
The combined insights from this research work have also been integrated into two standalone guides for on-going use by the SRL industry:
  1. The traceability implementation guide aims to directly support industry to improve their traceability practises:
  2. The traceability systems and technology products guide provides insights into suitable tools to support traceability at different levels and at different points along the supply chain.
Conclusions
This project has raised awareness of the importance of traceability within and along the southern rock lobster supply chain. The research team have engaged with the industry on their current practices and identified and demonstrated through trial and evaluation a range of mechanisms, tools and techniques to enhance SRL traceability systems. The production of a ‘Traceability Implementation’ guide provides the SRL industry with a genuine opportunity to take a step forward to ‘better traceability practises’ and it opens up the possibility for the industry to consider the development of an industry traceability platform for coordination and integration of an industry-wide traceability system built on GS1 standards.
Recommendations
Based on the results and outputs from this project it is evident that there are still several challenges to the implementation of standard industry-wide traceability practises. However, this project has raised awareness and demonstrated a way forward to achieving this goal. To that end, the following recommendations can be made:
  • Continued consultation and engagement with industry stakeholders to strengthen the desire and willingness to progress traceability improvements across the industry. The benefits of traceability and the value it adds to the fishery are well recognised, indicating that further research into the development and implementation of specific, actionable traceability system elements will likely be well received.
  • The occurrence of harmful algal blooms such as Alexandrium tamarense, which cause the build-up of paralytic shellfish toxin, will force the industry to adopt some system of traceability or face closures and brand damage. As blooms have been limited to Tasmania thus far, this segment of the SRL industry is at particular risk. The implementation of at least batch level traceability with evidence of where lobsters were caught will help to mitigate this risk.
  • Further research into the development of tagging approaches and alternatives should be a priority. Tagging lobsters with unique identifiers is a critical element of any highly precise traceability system. Unfortunately, it is also labour intensive and time consuming and represents a barrier to acceptance and uptake by the industry. The development of a new tagging approaches or even ‘tagless techniques’ hold promise and should continue to be investigated.
  • Brand differentiation between rock lobsters is a potential area of growth for the SRL industry. Although the SRL industry considers itself to be producing a premium product, the reality is that there is currently no differentiation between SRL and other rock lobsters at markets and wholesalers in China. Further development of the SRL brand and provenance can take advantage of this and position SRL as a prestige product.
  • Industry members expressed enthusiasm for the development of water quality monitoring devices that can be incorporated into traceability systems. The understanding and management of water quality is variable across the industry, so tools that assist the measurement and recording of water quality will help to improve holding practises as well as provide evidence of good care of stock along the supply chain.
Project Extension
Building on these recommendations is the idea of developing a traceability software platform which could integrate batch and item level technologies along the supply chain and underpin SRL quality and safety auditing programmes. The key elements of this platform have been trialled as part of this existing project so there is a genuine opportunity to significantly extend this platform to all industry participants and to facilitate moving the whole industry forward in its adoption of traceability better practises.
Another important area for consideration for project extension results from on-going doctoral research that has been aligned to this research project. This PhD research is continuing to explore new technologies using digital image processing to develop approaches for ‘tagless’ hybrid traceability solutions integrating automatic grading with biometric identification through use of computer vision and AI for use along the rock lobster supply chain including for providing provenance authentication information to end-consumers.
 

Vulnerability of the endangered Maugean Skate population to degraded environmental conditions in Macquarie Harbour

Project number: 2016-068
Project Status:
Completed
Budget expenditure: $421,129.00
Principal Investigator: Jeremy Lyle
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 Mar 2017 - 30 Jul 2020
Contact:
FRDC
TAGS
Remote Sensing
Physiology
Ecosystem
Biology
SPECIES
Skates

Need

The physio-chemical conditions in Macquarie Harbour have changed markedly since European settlement and the general decline in DO since 2009, which occurred at the same time as the rapid expansion of marine farming operations, is likely to have had a significant impact on many resident species, including the endangered Maugean Skate. Given the species poor ability to cope with low DO, any reductions in bottom DO concentrations are expected to directly influence the distribution of the skate, highlighting the need to better understand the oxygen demands of the species. Current generation acoustic tags capable of measuring DO and activity in the field, which when combined with laboratory studies, represent methods to examine tolerance and responses to varying levels of DO. Bottom DO also has implications for the development and survival of skate eggs. Limited information suggests that eggs are deposited at depths of > 20 m where they are likely to be increasingly exposed to low DO concentrations. An understanding of the relationships between environmental conditions and the development and survival of embryos, coupled with the depths in which eggs are deposited, has particular relevance to assessing the implications of changing environmental conditions on future recruitment and productivity of the Maugean Skate population.

Furthermore, the ability to monitor the status of this population, especially given the rate and extent of recent environmental changes in Macquarie Harbour is critical to assess its future viability. Tracking size composition, including data from previous studies, has the potential to provide a baseline against which reduced recruitment (if linked to the changed environmental conditions) could be detected.

The maintenance of best environmental practices by the aquaculture industry supported by effective monitoring and environmental management policies represent essential requirements if industry and Maugean Skate populations are to coexist.

Objectives

1. Determine the distribution of Maugean skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
2. Examine the relationship between environmental conditions and survival and viability of Maugean skate eggs.
3. Determine what DO levels Maugean skate experience in Macquarie Harbour, particularly when in deeper waters.
4. Determine the physiological costs of the DO levels Maugean skate are exposed to in Macquarie Harbour.
5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.

Final report

ISBN: 978-1-922352-39-2
Authors: David Moreno Jeremy Lyle Jayson Semmens Andrea Morash Kilian Stehfest Jaime McAllister Bailee Bowen and Neville Barrett
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.
Final Report • 2020-10-01 • 3.41 MB
2016-068-DLD.pdf

Summary

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species.  The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. 
The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change.  Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate.  In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action. 
Objectives
The primary aim of this study is to establish the mechanistic links between the environmental conditions experienced by the Maugean Skate across multiple life stages and the implications of the changing environment in Macquarie Harbour.  Specific objectives include:
  1. Determine the distribution of Maugean Skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
  2. Examine the relationship between environmental conditions and survival and viability of Maugean Skate eggs. 
  3. Determine what DO levels Maugean Skate experience in Macquarie Harbour, particularly when in deeper waters.
  4. Determine the physiological costs of the DO levels Maugean Skate are exposed to in Macquarie Harbour.
  5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
  6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.
Methodology
The study comprised five main components: (1) systematic field surveys of skate egg distribution, (2) laboratory study of embryo development; (3) field assessment of skate behaviour in relation to environmental conditions; (4) laboratory assessment of physiological responses to conditions experienced in the wild; and (5) fishery-independent surveys to examine the potential to inform on changes to population status.

A combination of beam trawl and dive surveys was employed to sample for Maugean Skate egg cases in areas of known high skate abundance.  Egg capsules collected in the field were reared in the laboratory to describe embryonic development and gestation period.  Acoustic telemetry was used to examine links between environmental conditions (i.e. dissolved oxygen and temperature) and the distribution, movement and habitat use of the Maugean Skate within Macquarie Harbour. An acoustic array comprising 52 acoustic receivers was deployed in the Table Head/Liberty Point region of Macquarie Harbour and 25 adult Maugean Skate were externally tagged with multi-sensor acoustic tags capable of continuously transmitting information on the depth, temperature and dissolved oxygen concentrations experienced by the individuals over a 12-month period. Physiological trials were conducted in a purpose-designed field laboratory to examine physiological responses to low DO and low salinity exposure, replicating environmental conditions experienced by the skate in Macquarie Harbour.  Gillnet surveys were undertaken to extend the time series of Maugean Skate size composition data and evaluate its potential as an indicator of changing population status.  

Key findings
Maugean Skate eggs were found across a wide range of depths (2.5 - 33 m) but appear to be most abundant in relatively shallow sites (< 10 m). Based on an analysis of the condition of egg-capsules, hatching success was estimated to be about 40%, which is comparable to success rates reported for other temperate skate species.  An egg reared under laboratory conditions hatched 31 weeks (~ seven months) after oviposition.  Respiratory channels opened after 15 weeks, exposing the embryo to external environmental conditions for over half of the gestation period.  These findings indicate that, depending on the depths at which eggs are deposited in the wild, embryos will experience a range of dissolved oxygen, salinity and temperature conditions, reflective of localised fluctuations in environmental conditions.  The implications of these varying conditions for development and survival are unknown.

This study represents the first use of animal-borne acoustic sensors to monitor long-term dissolved oxygen conditions experienced by a coastal elasmobranch and the links with behaviour. The results showed that skate are subject to wide ranging fluctuations in water chemistry. For instance oxygen levels experienced ranged from normoxic (50-100%), hypoxic (20-50%) and to near anoxic (~0-20%), with individuals often experiencing substantial variation (as high as > 90%) in the range of DO levels within the same day.
Adult Maugean Skate exhibited a high level of site selectivity and site fidelity across a relatively small spatial extent and with a strong preference to depths between 7.5 and 12.5 m. Despite individual variation in long-term residency, noting that several individuals appeared to permanently exit the study area, the tagged skate showed a clear preference towards the Table Head and Liberty Point areas. Furthermore, home ranges calculated using continuous time movement models showed a high degree of spatial overlap in the core home ranges (50% utilisation distribution, UD) of each of the individuals.  Their extended activity areas (95% UD) did, however, change throughout the year corresponding to variation in environmental conditions.  For instance, a sharp increase in surface water temperature and declines in mid- and deep water dissolved oxygen levels during summer resulted in all detected individuals spending time at shallow depths before returning to their preferred depths. While the shallow sites provided access to improved oxygen conditions, higher temperatures and exposure to hyposaline conditions will place an increased metabolic demand on individuals, potentially driving them to continuously move back into deeper waters where temperature and salinity conditions are more stable.  A large storm surge and subsequent oxygen recharge in March/April 2019 resulted in all tracked individuals expanding their extended activity areas considerably, including movement into deeper waters, while still maintaining a strong attachment to their core areas.
The present study shows that there is an intricate link between movement of the Maugean Skate and environmental conditions in Macquarie Harbour. The species appear to behaviourally modulate environmental stressors through movement, likely balancing optimal habitat requirements against the energetic cost of chronic hypoxia in deeper waters and increased thermal and osmoregulatory stress at shallow sites. Such behavioural plasticity may constitute a key adaptation that to date has enabled the species to tolerate such a challenging environment that Macquarie Harbour represents.  However, since individuals continued to utilise the same core UD and preferential depth range, despite these areas being subject to the largest daily fluctuations in water chemistry conditions experienced by the skate, this behavioural plasticity appears to be limited to their extended use areas. Therefore, the site attached behaviour of the skate suggest that these core sites likely provide an advantage that outweighs the cost of exposure to unfavourable environmental conditions, such as access to prey that may not be as readily available elsewhere within the estuary. 
Physiological experiments demonstrated that adult Maugean Skate are quite capable of surviving chronic exposure to hypoxic conditions (< 20% DO) by using metabolic depression as a survival strategy. Metabolic depression does, however, occur at the cost of other energy intensive life history processes, such as growth, foraging and reproduction.  As such, metabolic depression cannot be sustained long-term, and as a result skate may seek oxygen in the shallower waters of the harbour where they will encounter hyposaline conditions.  Maugean Skate are unusual in that they are the only known species of skate to live exclusively in a euryhaline environment (areas with a wide range of salinities) and, based on the range of depths utilised, are constantly exposed to a wide range of salinities.  Routine metabolic rate appeared to be higher following acclimation to hyposaline conditions, although the corresponding statistical test only showed near-significance.  Since individuals appear to utilise shallow areas as a DO refuge during the summer months, they will also be exposed to higher temperatures which in turn will result in further metabolic stress. 
Physiological data based on a single individual suggests that neonates are oxyconformers (rate of oxygen consumption dependent on environmental DO), implying that even at an early age, Maugean Skate may be able to tolerate short-term hypoxic events through an increased reliance on anaerobic metabolism. The point below which oxygen uptake became negligible in the neonate was higher (~ 66% DO) compared with adults (10-25% DO), implying a lower tolerance threshold which could have important implications for survivorship of early life stages, especially in relation to the range of environmental conditions experienced in Macquarie Harbour.
During this study, an unexpectedly high proportion of tagged individuals died.  Although causality cannot be established, the timing of these events suggest that the mortalities were unlikely to have been a direct consequence of tagging.  Most mortalities (8 out of 11) were clustered in two discrete periods that corresponded with marked changes in environmental conditions within the core habitat used by the skate. In addition, behavioural changes (based on change point analysis) were observed at the same time in virtually all surviving individuals.  It is feasible, therefore, that the deaths may have been related to stress caused (directly or indirectly) by the significant changes in the environmental conditions of the harbour. If this is the case, then recent changes in the environmental health of the harbour (especially dissolved oxygen levels), coupled with the consequences of climate change (including occurrence of extreme weather events), may already be challenging the skate’s capacity to cope with the environmental conditions in Macquarie Harbour.
Deriving an estimate of the effective population size of the Maugean Skate in Macquarie Harbour has proven challenging and there is a high degree of uncertainty associated with current estimates that limit their applicability in monitoring the continuing status of the population. An analysis of research gillnet data collected since 2012 suggests a reduction in the relative abundance of juvenile and sub-adult individuals and as well as an increase in the size of the larger individuals (adults) in the catches through time.  Despite uncertainty as to the significance of the size composition data in terms of representing trends in population status, a recent decline in recruitment, possibly due lower hatching success or juvenile survival, coupled with adult growth represent plausible scenarios that could produce the changes observed.  
Implications
This study provides a greater understanding of the ecology and life history of the Maugean Skate and describes for the first time some of the behavioural and physiological adaptations that have enabled the species to survive in such a unique and challenging environment as Macquarie Harbour. Our results suggest that the species can mitigate some environment variability by a combination of behavioural (movement) responses and physiological capability.  However, the vulnerability of early life stages to the changing environmental conditions, long-term changes in the size structure of the population, and the mortality of some tagged individuals following significant environmental events collectively highlight the vulnerability of the Maugean Skate in Macquarie Harbour and the need to consider further conservation action to support the persistence of this unique micro-endemic skate. 
In addition to addressing uncertainties around the apparent changes in the size (and age) structure of the population through further research fishing, there is an urgent need to investigate cost-effective and non-invasive approaches to estimate population size and mortality rates, which can be applied to track population status and health over time.  Importantly, managing the known anthropogenic impacts on the environmental health of Macquarie Harbour, both in terms water column and benthic conditions, will ultimately prove crucial to the success of any conservation strategy for the Maugean Skate. A multi-stakeholder and holistic environmental management approach for Macquarie Harbour should be considered as part of this strategy.

Social Science and Economics Research Coordination Program (SSERCP)

Project number: 2015-300
Project Status:
Completed
Budget expenditure: $160,416.00
Principal Investigator: Emily Ogier
Organisation: University of Tasmania (UTAS)
Project start/end date: 28 Feb 2015 - 27 Feb 2018
Contact:
FRDC
TAGS
Workshop
Training
Stakeholder
Social Science
Social Science

Need

Phases I&II of the SSRCP successfully raised awareness of the need for, and increased the use of, social science fisheries research to improve fisheries and aquaculture sector outcomes. SSRCP I&ll also highlighted the need for a social sciences reference group for FRABs, researchers, industry and managing agencies, and for coordination of social science fisheries research.

Across this same period the societal needs and drivers impacting marine resource management have increased in importance (Barclay 2012; Mazur, Curtis et al. 2014). Further research activity is needed to address challenges regarding the social impacts, acceptability and sustainability of fisheries and aquaculture and to better integrate research across the social sciences (including economics) and between social and biological sciences. The 2014 FRDC Social Sciences Survey indicated broad support for continuation of SSRCP activity and highlighted the Program’s role in linking social science research outputs with decision-making and representations of the industry, brokering collaborations and in facilitating the uptake of FRDC’s key national interest projects.

While there is clear need for continuing the activities that have been the SSRCP’s remit, there is the scope to extend the suite of activities by working closely with the 'FishEcon' project and, post- 30/06/15, with its legacy activities (in particular the FishEcon Network). Such a partnership will result in efficiencies in the delivery of project activities, including newsletters and other networking activities, and in project administration; provide the opportunity to develop tighter integration between economics and the social sciences in research, extension and capability building.

Objectives

1. Support the FRDC to meet relevant objectives as outlined in its 2015-2020 RD&E Plan and the National Fishing and Aquaculture RD&E Strategy, as well as other needs arising from FRDC's existing programs and projects
2. Collaborate with the industry and managing agencies to identify emerging issues in wild harvest, aquaculture, post harvest, recreational and indigenous fishery sectors and the associated key social science and economics research needs
3. Co-ordinate and undertake the communication of key social science and economic research needs to the research community and research outcomes of the Program to fishers and management agencies.
4. Provide program management for social science and economics projects to ensure quality and relevance by undertaking evaluation and review of project proposals, and milestone and final reports.
5. Build further capability in fisheries social sciences and economics research to meet the needs of industry and managing agencies in addressing emerging issues in wild harvest, aquaculture, post harvest, recreational and indigenous fishery sectors

Final report

Author: Emily Ogier and Sarah Jennings
Final Report • 2018-01-01 • 644.67 KB
2015-300-DLD.pdf

Summary

The SSERCP project has been successful in providing timely and relevant advice to the drafting and reviewing stages of RD&E priorities, projects and reports in order to maximise beneficial outcomes of this investment for fisheries and aquaculture. It has been successful in supporting the FRDC and researchers in completing a number of high profile, high impacts projects (including the Social and Economic Evaluations of NSW Coastal Fisheries and Aquaculture, 2014-301 and 2015-302, and Beyond GVP 2013-301). It has also been able to establish strong working networks with leaders of other FRDC subprograms and a number of the RACs and IPAs. Capability in economics has been increased under the project, through the Higher Degree Research student projects commenced under the FishEcon project, and the delivery of the Masterclass in Fisheries Economics to managers and industry representatives alike.
 
The implications of the SSERCP have included:
• Establishment of a trusted multi-disciplinary reference group for industry, management agencies and research providers alike
• Improved collaborations, efficiencies and impact in delivering the social science and economic RD&E that FRDC stakeholders seek
• Improved networks and capability amongst researchers and professional members of industry and government able to deliver and adopt the social science and economic RD&E required
• A way forward for developing and expanding engagement activities by industry and government to address issues arising from reduced social license and acceptability, based on best available information (the ‘License to Engage handbook’)
 
Major recommendations arising from the SSERCP mid term evaluation include:
• That the FRDC should continue to support the coordination of social science and economics RD&E for fisheries and aquaculture; and, specifically,
• That the FRDC establish a social sciences and economics research subprogram with funds to allocate to RD&E, and in the design of such a subprogram:
  o Seek further mechanisms to consult and collaborate with the RACs and IPAs;
  o Improve the extension and adoption of major social science and economics RD&E project outputs; and
  o Increase awareness of its role and the role of social science and economics RD&E across the broader FRDC membership.
Environment
PROJECT NUMBER • 2015-024
PROJECT STATUS:
CURRENT

Managing ecosystem interactions across differing environments: building flexibility and risk assurance into environmental management strategies

Summary The overarching aim of this research was to provide an improved understanding of the environmental interactions of Atlantic Salmon farming and to provide recommendations to both government and industry on monitoring and management strategies that are appropriate to the level of risk...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Storm Bay
Rac Tas
Climate Resilience
Aquaculture
SPECIES
Atlantic Salmon
Blacklip Abalone
Greenlip Abalone
Trouts
Whitebaits
Blank
PROJECT NUMBER • 2014-726
PROJECT STATUS:
COMPLETED

SCRC: Measuring condition of lobsters to improve management of harvesting around periods of high transport mortality

This project provides the first comprehensive quantitative assessment of the health, physiological and nutritional condition of brindle and red lobsters from four different fishing areas of Tasmania at the start of the 2015 fishing season. Lobsters size (carapace length), baseline concentrations of...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Stock Assessment
Physiology
Mortality
Harvest Strategy
Animal Health
Industry
Environment
PROJECT NUMBER • 2014-241
PROJECT STATUS:
COMPLETED

Reassessment of intertidal macroalgal communities near to and distant from salmon farms and an evaluation of using drones to survey macroalgal distribution

The salmon farming industry has significantly expanded in South-eastern Tasmanian both in production and in number and location of farms. Along with this expansion has been an increasing concern from the general community about the effects of salmon farms on the environment. This includes a reported...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Waste
Habitat
Electronic Monitoring
Distribution
Co-Management
SPECIES
Atlantic Salmon

TSGA IPA: Understanding Dorvilleid ecology in Macquarie Harbour and their response to organic enrichment

Project number: 2014-038
Project Status:
Completed
Budget expenditure: $87,135.40
Principal Investigator: Jeff Ross
Organisation: University of Tasmania (UTAS)
Project start/end date: 1 Jan 2015 - 29 Jun 2015
Contact:
FRDC
TAGS
Pollution
Electronic Monitoring
Disease
Aquaculture
SPECIES
Atlantic Salmon

Need

Previous research has shown a clear impact gradient associated with cage salmon farming operations, and that presence of bacterial mats (Beggiatoa) and proliferation of opportunistic species are features commonly associated with high levels of organic enrichment (e.g. Pearson & Rosenberg, 1978). The presence of opportunists, such as Capitellid worms, being classified as representative of “unacceptable impact” (Macleod et al., 2004). This premise has been validated in SE Tasmania and underpins regulatory monitoring requirements statewide (DPIPWE, 2004).

The understanding that proliferation of opportunists represents deteriorating conditions was translated to monitoring protocols in Macquarie Harbour, but the relationship between opportunists and the level of enrichment was not explicitly tested in this region. However, video surveys suggest that in Dorvilleid worms rather than Capitellids were the species most indicative of organic enrichment effects(DPIPWE, 2004). Dorvilleids can tolerate anaerobic sediments and high levels of hydrogen sulphide (Levin et al. 2013) and are known to be indicators of the impacts of finfish aquaculture (e.g. Paxton et al. 2010).

However, Macquarie Harbour is ecologically very different to other farming areas in SE Tasmania; the sediments are inherently depauperate, largely epibiotic and spatially patchy. A recent study in Canada has highlighted the need to better understand the relationships and compliance thresholds for established enrichment indicators (i.e. Beggiatoa sp and opportunistic polychaete complexes) in systems where ecological patchiness may occur (Hamoutene et al 2014); suggesting that, where there is significant potential for small scale spatial variability, normal successional responses may not be as reliable. Consequently, the responses may not be consistent with expectations developed from southern Tasmanian regions.

In this context it is important to identify the relationship between Dorvilleids and sediment condition; determining the reliability of this species as an indicator of sediment condition, and characterising the environmental conditions associated with changes in Dorvilleid abundance.

Objectives

1. Review the international literature to establish the current state of knowledge regarding Dorvilleid ecology, and in particular, their response to organic enrichment. This will include a review of their current use as indicator of the impacts of finfish aquaculture.
2. Carry out targeted field survey at selected leases to identify the relationship between Dorvilleids and sediment condition, characterising the environmental conditions associated with changes in Dorvilleid abundance.
3. Based on the finding of 1. and 2. determine the reliability of this species as an indicator of sediment condition in Macquarie Harbour
4. In conjunction with industry and government stakeholders make recommendations on the future use of Dorvilleids in regulatory monitoring of Salmonid aquaculture in Macquarie Harbour
Environment
PROJECT NUMBER • 2014-032
PROJECT STATUS:
COMPLETED

Improved understanding of Tasmanian harmful algal blooms and biotoxin events to support seafood risk management

The 2012 Tasmanian biotoxin event represents a paradigm shift for seafood risk management in Tasmania and Australia as a whole. The causative dinoflagellates are extremely difficult to identify by routine plankton monitoring, and are toxic at very low cell concentrations (50-100 cells/L). Sampling...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Toxin
Rac Tas
Oceanography
Market Opportunities
Electronic Monitoring
SPECIES
Southern Rock Lobster
Greenlip Abalone
Commercial Scallop
Sydney Rock Oyster
Pacific Oyster
View Filter

Research

Category

Product Type

Species

Organisation