625 results
Blank
Industry
Communities

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
:

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. 
Industry

Development of resources and equipment to enable best practice in the humane dispatch of sharks caught by commercial fishers in the NT

Project number: 2022-028
Project Status:
Current
Budget expenditure: $148,400.00
Principal Investigator: Ben Diggles
Organisation: DigsFish Services Pty Ltd
Project start/end date: 31 Dec 2022 - 29 Dec 2023
:

Need

The so called pragmatic approach to the welfare of aquatic animals (Arlinghaus et al. 2007) measures welfare status using a variety of well-established, un-controversial physiological and functional parameters (Rose et al. 2014, Browman et al. 2019). For example, all finfish, crustaceans and cephalopods can experience stress, which can lead to poor welfare outcomes (Rose et al. 2014). From an animal welfare perspective, the overall aim to maximise fish welfare during capture is to minimise stress within the constraint of practices inherent to the relevant fishing sector (Mazur and Bodsworth 2022).
Using this pragmatic approach, the Aquatic Animal Welfare Working Group (AAWWG) which was formed under the Australian Animal Welfare Strategy (AAWS, 2005-2014), developed a range of Overarching Welfare Principles which related to finfish harvested from the wild in commercial fishing industries.
Out of the eight Overarching Principles developed by the AAWWG, as pointed out by Mazur and Bodsworth (2022) the three that are most relevant to the commercial wild harvest industry are:
1. Timely handling from capture to death is essential to minimise stress;
2. Capture methods should be designed to minimise the capture of unwanted species
3. Any fish selected for harvest should be killed as rapidly as possible, by humane means suitable for the species.
To address the legislative issues under the new Act, meet current and future fish welfare challenges, and maintain their social license to fish, commercial fishers targeting sharks in the NT need to develop workable and effective standards for handling and dispatching sharks which can be recognised and prescribed under the new Regulations.
Since shark fisheries are specialist fisheries which were not covered by the AAWWG during the AAWS, there is a need to develop specific resources to assist the industry with humane dispatch of sharks.
Science shows that brain destruction by pithing or “iki-jime” is the fastest way to dispatch finfish, resulting in the lowest levels of stress and maximising the quality and shelf life of the resulting fish product (Poli et al. 2005, Diggles 2015). However, the brains of sharks are small and vary in location between species, which is why this project is being proposed and is necessary to determine the brain location of the sharks most commonly captured in the NT shark fishery, and then examine various methods of rapidly destroying the brain, in order to develop guidelines and best practice protocols for their humane dispatch. Importantly, it should be noted that this is an industry driven project.

References

Arlinghaus R, Cooke SJ, Schwab A, Cowx IG (2007). Fish welfare: A challenge to the feelings based approach, with implications for recreational fishing. Fish and Fisheries 8: 57-71.

Browman HI, Cooke SJ, Cowx IG, Derbyshire SWG, Kasumyan A, Key B, Rose JD, Schwab A, Skiftesvik AB, Stevens ED, Watson CA, Arlinghaus R (2019). Welfare of aquatic animals: where things are, where they are going, and what it means for research, aquaculture, recreational angling, and commercial fishing. ICES Journal of Marine Science 76: 82–92. doi:10.1093/icesjms/fsy067

Diggles BK (2015). Development of resources to promote best practice in the humane dispatch of finfish caught by recreational fishers. Fisheries Management and Ecology DOI: 10.1111/fme.12127

Mazur N, Bodsworth A (2022). Practicing aquatic animal welfare: Identifying and mitigating obstacles to uptake and adoption by the Australian Seafood Industry. Final Report for FRDC Project No 2019-023, March 2022. 60 pgs.

Poli BM, Parisi G, Scappini F, Zampacavallo G (2005). Fish welfare and quality as affected by presaughter and slaughter management. Aquaculture International 13: 29-49.

Rose JD, Arlinghaus R, Cooke SJ, Diggles BK, Sawynok W, Stevens ED, Wynne CD (2014). Can fish really feel pain? Fish and Fisheries 15: 97–133.

Objectives

1. Obtain all relevant permits. Review of literature (primary and grey) and current NT industry practice to inform Objective 2.
2. Collect at least 3 representative specimens (small, medium large) of each of the main shark species (up to 12) encountered by the commercial fishing industry in the Northern Territory (NT), and precisely identify their anatomical brain location.
3. Assess the effectiveness of various different tools and techniques for dispatch of small and large sharks (percussive stunning (blunt trauma inflicted using a baseball bat) vs spinal section vs shooting vs pneumatic captive bolt gun vs cartridge powered captive bolt gun vs spring loaded captive bolt gun vs (depending on OH&S requirements) electrical stunning.
4. Update the existing code(s) of practice adopted by the commercial fishing industry in the NT to include the best practice information on dispatch of sharks as prescribed under the new Regulations (Animal Protection Act 2018 (‘the new Act’) and the Animal Protection Regulations 2020 ‘the new Regulations’ in the NT.
5. Update existing electronic extension resources (www.ikijime.com, Ikijime Tool phone applications) to include the new information on location of shark brains.
6. Extend this information to the commercial fishing industries in the NT.
Environment
Industry
PROJECT NUMBER • 2016-262
PROJECT STATUS:
COMPLETED

RAC QLD: Queensland Seafood Marketing Symposium

The initial proposal to hold a marketing symposium in Queensland was based on the need to bring Industry together with particular reference to the post-harvest sector to provide, exchange and discuss information in an open forum regarding trends and/or needs in the existing value chain process which...
ORGANISATION:
Queensland Seafood Marketers Association Inc (QSMA)
Environment
Environment
View Filter

Species

Organisation