330 results

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. 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
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Murray Cods
Industry
PROJECT NUMBER • 2023-005
PROJECT STATUS:
CURRENT

Research to support the development of a Tasmanian Sardine Fishery

This study documents the first comprehensive evaluation of the spawning biomass of the South Eastern Stock of Australian Sardine (Sardinops sagax). This stock occupies continental shelf waters from the Victorian-South Australian border, east through Bass Strait and along the north-western and...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Rac Tas
Fisheries Management
Biomass
SPECIES
Sardines
Blank
PROJECT NUMBER • 2022-075
PROJECT STATUS:
COMPLETED

National Workshop to develop a regional collaborative plan to control the invasive Longspined Sea Urchin (Centrostephanus rodgersii)

The 2023 National Centrostephanus Workshop was convened by the Department of Natural Resources and Environment Tasmania. The workshop brought together 130 representatives from industry, government, research, Aboriginal communities, recreational fishing groups, and the community to: • Identify...
ORGANISATION:
Department of Natural Resources and Environment Tasmania (NRE TAS)
TAGS
Rac Vic
Rac Tas
Rac Nsw
Invasive Species
Climate Change
SPECIES
Sea Urchins
Environment
PROJECT NUMBER • 2021-119
PROJECT STATUS:
COMPLETED

Improving bycatch reduction strategies and escape vents in Queensland Mud Crab fisheries

The Queensland Crab Fishery is an iconic fishery, which encompasses the harvest of mud crabs (Scylla serrata, the Giant Mud Crab, and Scylla olivacea, the Orange Mud Crab) and Blue Swimmer Crabs (Portunus armatus and Portunus pelagicus), predominately using baited crab pots of various designs. The...
ORGANISATION:
Department of Primary Industries (QLD)
TAGS
Threatened Endangered Protected Species
Recreational Fishing
Rac Qld
Fishing Gear
Bycatch
SPECIES
Mud Crabs
Adoption
PROJECT NUMBER • 2017-221
PROJECT STATUS:
COMPLETED

Raise awareness of the guidelines developed by the AAWWG (Aquatic Animal Welfare Working Group) with industry and review their adoption, uptake rates and utility

During the 2017 FRDC Lead, Collaborate, Partner Stakeholder Workshop delegates identified a need to assess the success of the work undertaken by the Aquatic Animal Welfare Working Group (AAWWG) from 2005 – 2013 and to determine what research, development and extension activities were needed to...
ORGANISATION:
Safe Sustainable Seafood Pty Ltd
TAGS
Wild Catch
Traceability
Sustainability
Supply Chain
Recreational Fishing
People
PROJECT NUMBER • 2022-153
PROJECT STATUS:
COMPLETED

Fishing and Aquaculture Workforce Capability Framework

In 2023 RM Consulting Group (RMCG) was contracted by FRDC to develop a Fisheries and Aquaculture (F&A) Workforce Capability Framework (hereafter referred to as the Framework) that would be used as a high-level, standardised tool across all F&A sectors. The FRDC and other groups in leadership...
ORGANISATION:
RM Consulting Group (RMCG)
TAGS
Workforce
Leadership
Capacity Building
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