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Identifying population connectivity of shark bycatch species in NT waters

Project number: 2020-036
Project Status:
Completed
Budget expenditure: $66,430.00
Principal Investigator: Sam Banks
Organisation: Charles Darwin University (CDU)
Project start/end date: 3 Dec 2020 - 9 Dec 2021
Contact:
FRDC
TAGS
Stock Assessment
Rac Nt
Offshore
Modelling
Harvest Strategy

Need

This project is needed for three main reasons:

1. It directly addresses a NT RAC priority in the 2019 call for funding applications relating to improving sustainable yield estimates to inform stock assessment programs for undefined target species and protected species in the Offshore Net and Line Fishery. The project will support sustainable fishing practices for important commercial fisheries in the NT and the development of new commercial opportunities within these fisheries: The impacts of fishery activities on these species, either through bycatch or targeted harvest, are difficult to assess in the absence of information on population connectivity and stock structure.

2. The project will develop capacity for fisheries research and monitoring in NT waters. Genetics methods are widely applied to fisheries research and monitoring and training of an early career fisheries scientist in the application and interpretation of genetic data will be a key outcome of this project.

3. The project will provide key information to support the transition of these species from bycatch to a harvested byproduct species, including an evaluation of leading-edge genetic techniques in fisheries assessment and monitoring.

Objectives

1. To develop population connectivity model for Whitecheek and Milk Shark
2. To develop capacity for research and monitoring of shark species within the Northern Territory
3. To evaluate the utility of genetic techniques in fisheries monitoring

Final report

ISBN: 978-1-922684-78-3 (Print), 978-1-922684-79-0 (Web)
Authors: Sam Banks Amy Kirke Fernanda Alves Grant Johnson and David Crook
Final Report • 2024-10-01 • 1.08 MB
2020-036-DLD.pdf

Summary

Charles Darwin University and the Northern Territory (NT) Department of Industry, Tourism and Trade (DITT) Fisheries Division used genetic data to investigate the population structure of two small tropical shark species (Milk Shark [Rhizoprionodon acutus] and Australian Blackspot Shark [Carcharhinus coatesi]), which are caught as bycatch from commercial fisheries in the NT. 
 
The aim of this study was to gain information on the genetic stock structure to inform the future management of these two species in the NT. This project was conducted in parallel with a PhD project investigating the biology and ecology of both species for applications to fisheries management. There is motivation by the NT Government to develop these two shark species into a commercial product. This project used genetic analysis to understand the patterns of connectivity of populations of these two shark species in NT waters and adjacent regions, including northern Western Australia and Papua New Guinea.
 
These two shark species that are captured as bycatch in the NT Demersal Fishery have the potential to be developed into a byproduct to add value to that fishery. A sustainable commercial harvest of these two species could greatly reduce the waste from fisheries, where they are currently abundant and caught in relatively large numbers. We address current knowledge gaps in biological information about populations of R. acutus and C. coatesi to inform the potential development of a byproduct fishery for these two species in the NT.
 
Genetic data from R. acutus and C. coatesi strongly suggest that each species exists as a single, highly connected population in the NT. Genetic differentiation among the sampling locations for each species was low, and genetic clustering analyses provided strong support for a single population of each species in the region. Sharks of both species captured within a single location (within 50 km of one another) were more genetically related than those further apart; however, this does not constitute evidence for multiple, spatially discrete populations of either species in NT waters. Preliminary applications of effective population size estimators were used, but further work is needed to determine if these can be used to indicate trends in abundance. 
 
The immediate implications of our research are for fisheries scientists and managers. Our results indicate that these two shark species can be monitored and managed in the NT under the assumption that each species occurs as a single population in this region. Parasite and vertebral chemistry data collected as part of a PhD project conducted in parallel with this project suggest that, for C. coatesi, individuals may be resident within certain regions (eastern versus western NT waters) but the genetic data collected here suggest that, on a generational timescale, both species occur as highly-connected populations across in the NT region. 
 
Our research has potential implications for commercial fishers, particularly from the NT Demersal Fishery. The information from our research will flow through to the industry by contributing to the information required to develop a byproduct fishery for the two species, by utilising bycatch and increasing economic return. 

Enhancing the understanding of the value provided to fisheries by man-made aquatic structures

Project number: 2018-053
Project Status:
Completed
Budget expenditure: $376,840.06
Principal Investigator: Euan S. Harvey
Organisation: Curtin University
Project start/end date: 29 Apr 2019 - 19 Mar 2020
Contact:
FRDC
TAGS
Social Science
Social Science
Recreational Fishing
Rac Wa
Policy

Need

The north west of Western Australia has productive commercial and recreational fisheries and extensive offshore oil and gas (O&G) infrastructure. These man-made structures support a range of demersal and pelagic fishes which are targeted by recreational and commercial fishers. As this O&G infrastructure reaches the end of its productive life, decisions on the best practice option for decommissioning must be made. The current policy for decommissioning requires complete removal. Regulators may support alternative strategies, such as leaving infrastructure in place, if risks and impacts are minimised and there are clear environmental, social and economic benefits to do so. It is thought that removal of infrastructure will decrease catch rates and have negative ecological, economic (direct and downstream) and social consequences.

At the same time as the discussion is occurring about removing O&G infrastructure, there have been large investments in constructing and installing purpose built man-made aquatic structures on the seafloor for the express purpose of enhancing the experience of recreational fishers and SCUBA divers.

There is a need to deliver critical information on: 1) the ecological, economic and social value of these man-made structures to recreational and commercial fishers and other stakeholders; 2) the attitudes of stakeholders to man-made structures; and 3) the opportunities and risks of decommissioning strategies to fishers and other groups (e.g. tourism).

Policy regarding the removal of decommissioned structures will benefit from the increased clarity that this project will provide in regards to data requirements for socio-economic models and stakeholder consultation methods. Comparative assessments of decommissioning options rely on the existence of appropriate socio-economic data, a knowledge gap this project aims to fill. An understanding of the impact of man-made aquatic structures on recreational and commercial fisheries is a global priority, and as such this project has strong international importance and relevance.

Objectives

1. To develop conceptual qualitative, semi-quantitative and quantitative models for describing the socio-economic values and decide what information is needed to give stakeholders an understanding of the value of manmade aquatic structures in the marine environment.
2. To collate a list and description of the manmade aquatic structures in the marine environment in Western Australian and the associated social, economic and biodiversity data.
3. To collect and collate data on four manmade aquatic structures in the marine environment and develop and compare the costs and benefits of qualitative, semi-quantitative and quantitative models.
4. To develop a decision support system or framework for undertaking socio-economic evaluations of manmade aquatic structures which can be used throughout Australia and guide end users on how to develop qualitative, semi-quantitative and quantitative models depending on their information requirements.

Final report

ISBN: 978-0-646-84171-7
Author: Euan Harvey
Final Report • 20.59 MB
2018-053-DLD.pdf

Summary

In 2018, the state’s recreational and commercial fishers (represented by the peak bodies Recfishwest and WAFIC) commissioned a program of research as part of a Fisheries Research Development Corporation project aimed at documenting the social and economic values and benefits that stakeholders obtain from MMS in Western Australia. These structures include shipwrecks, artificial reefs, break walls, structures associated with harbours, jetties, marine navigation markers, and O&G infrastructure such as platforms, wells, and pipelines.
During 2019 and 2020 the researchers undertook seven online surveys which focussed on understanding the social and economic benefits and values that recreational and commercial fishers, divers and other users gained from using MMS in Western Australia. This was complemented by eleven focus groups which included representatives from the commercial and recreational fishers, but also the Oil and Gas (O&G) sector, regulators (state and federal), conservation, non-government organisations (NGOs), scientific sectors, and the general community. The researchers used data to develop five case studies representing a range of different structures and end users. These case studies focussed on inshore Thevenard Island subsea O&G infrastructure (incorporating recreational fishing), Woodside’s Echo Yodel offshore subsea O&G infrastructure (incorporating commercial fishing), the Exmouth Integrated Artificial Reef (recreational fishing), the Exmouth Navy Pier (diving tourism), and the iconic Busselton Jetty in Southwestern Australia, which is used for tourism, by recreational fishers, divers, swimmers and many other stakeholders. A guidebook was produced outlining the different methods of identifying social and economic values, along with the types of data required, and the approaches to collecting this data. The guidebook also outlines the advantages, disadvantages and resource needs for each method. A database of the MMS in Western Australia was also compiled and made accessible online.
Environment
Environment
Blank
Industry
PROJECT NUMBER • 2019-126
PROJECT STATUS:
COMPLETED

Assessing the biosecurity risk of uncooked whole and eviscerated barramundi and grouper in relation to exotic viruses

Presently, the Australian Barramundi farming industry enjoys freedom from numerous internationally significant diseases including all from the Megalocytivirus genus of iridoviruses. These diseases are known to be causing severe impacts on farmed Barramundi and other species in southeast Asia and...
ORGANISATION:
Future Fisheries Veterinary Service Pty Ltd (FFVS)
TAGS
Wild Catch
Trade
Supply Chain
Invasive Species
Indigenous
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