Assessing current data and alternate data collection methods relating to recreational catches of tropical tuna and billfishes

Project number: 2022-173
Project Status:
Current
Budget expenditure: $249,442.00
Principal Investigator: Barrett W. Wolfe
Organisation: Institute for Marine and Antarctic Studies (IMAS) Hobart
Project start/end date: 29 May 2023 - 30 Jun 2025
Contact:
FRDC
TAGS
Stock Assessment
Recreational Fishing
Rac Cmwth
Fisheries Management
Data
SPECIES
Tunas
Marlins

Need

The recreational sector of the Tropical Tuna and Billfish Fishery (TTBF) is an important component of the overall fishery. The recreational fishery has a number of distinct components – the organized club-based sector, the non-club sector and the charter sector. Some catch and catch-effort data, although incomplete, are available from the club-based and charter sectors, while data from the non-club sector, including the magnitude of that sector, are largely lacking. These uncertainties and gaps mean that the total Australian catch by the sector is unknown. However, recreational data may provide relative indicators of stock and fishery performance through time (e.g., CPUE), which could be valuable for monitoring TTBF stocks and the quality of the recreational fishery. This project will summarise existing recreational data available for the TTBF and evaluate their utility for monitoring, to guide immediate application and identify areas requiring further development.

A large component of the total catch of the TTBF recreational sector, is released. Post release mortality is a re-occurring question that has been studied to some extent by the use of satellite telemetry in some target species (striped marlin, swordfish and to a lesser extent, yellowfin tuna). This project will additionally review available data for release rates which are required to apply estimates of post release mortality over the whole fishery.

While all five target species of the TTBF are also caught by the recreational sector, two species – striped marlin and yellowfin tuna – are particularly numerically important. In addition, a relatively new recreational fishery for swordfish has emerged in Victorian and Tasmanian waters, with potential to spread to other States, but is largely unmonitored. This project will assess these important species.

Aside from the five commercial target species within the TTBF, the recreational sector also targets and highly values other billfish species, especially black marlin, blue marlin and sailfish. These species are also caught as bycatch of the domestic commercial sector, although blue and black marlin are not permitted to be landed by commercial licence holders and are therefore discarded. Recreational data sources may provide the only cost-effective monitoring option for stocks of these non-commercial species.

Objectives

1. Review traditional and contemporary, cost-effective sources of recreational and charter catch and catch-effort data for Tropical Tuna and Billfish (including assumption and limitations of the data as well as a cost benefit analysis of methods)
2. Collate available data sources to improve the understanding of the potential catch on local abundance/availability of commercial, recreational and charter target species
3. Provide recommendations on how recreational and charter catch data might be collected, standardized, and integrated in future decision-making

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PROJECT NUMBER • 2021-001
PROJECT STATUS:
CURRENT

The emerging Billfish fishing grounds of northern Australia: fisheries description, movements, and hot-spots

1. To provide a description of the emerging recreational fishery for billfishes in northern Australia, including analyses of historic and ongoing conventional tagging data, historical records of billfish larvae (1956−1981) to map spawning areas, and evaluate whether historical commercial catch data...
ORGANISATION:
Charles Darwin University (CDU)

Two Marlins, one stone

Published: 21 March 2023 Updated: 22 March 2023
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DATE 22 Mar 2023
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FEEDBACK/STORY SUGGESTIONS FRDC +61 2 6122 2100 frdc@frdc.com.au

Tristan Guillemin, the winner of FRDC’s 2023 ‘Science and Innovation Award’, talks about his Award-winning project and how he was able to ‘kill two birds with one stone’.

The Science and Innovation Awards recognise Young People in Agriculture, Fisheries and Forestry who undertake innovative science projects that contribute to the ongoing success and sustainability of Australia’s agricultural industries.

The emerging Billfish fishing grounds of northern Australia: fisheries description, movements, and hot-spots

Project number: 2021-001
Project Status:
Current
Budget expenditure: $442,416.00
Principal Investigator: Keller Kopf
Organisation: Charles Darwin University (CDU)
Project start/end date: 9 Dec 2021 - 27 Mar 2025
Contact:
FRDC
TAGS
Recreational Fishing
Rac Nt
SPECIES
Black Marlin
Marlins

Need

There is a need to increase economic growth of environmentally sustainable industries in northern Australia and this project aims to increase recreational billfish fisheries tourism and facilitate management of this emerging resource. The tourism industry in Australia including recreational fisheries and associated travel sectors have been severely impacted due to Covid-19. With an estimated economic value of $3185AUD per charter fishing trip, recreational billfish fisheries represent a high-value and sustainable option to help develop post-Covid-19 fisheries tourism in northern Australia.

There is an emerging recreational billfish fishery in Northern Territory waters but growth, participation and management of a sustainable fishery has been hampered by a lack of data and public awareness. Anecdotal evidence suggests that a recent increase in catches of sailfish and black marlin in waters off northern Australia may have been facilitated by the closure of Taiwanese Gillnet fisheries which operated in Australian waters between 1972 and 1986. However, there has been little scientific evaluation of past or current billfish fisheries resources in the region, and better quality fisheries data and information on the spatial distribution and seasonal movement patterns are required to guide development and management of sustainable fisheries. The catch-and-release billfish fisheries of northern Australia are likely to be sustainable but stocks are likely to be affected by fisheries in the broader Indo-Pacific region and further information is needed to inform assessments as part of the Status of Australian Fish Stocks Report. As is this a developing fishery there is a need to form a ground up educational programs on the best practices for responsible handling of billfish in the NT recreational fishery.

Objectives

1. To provide a description of the emerging recreational fishery for billfishes in northern Australia, including analyses of historic and ongoing conventional tagging data, historical records of billfish larvae (1956−1981) to map spawning areas, and evaluate whether historical commercial catch data on billfishes is available from Taiwanese gillnet fisheries (1972-1986).
2. To evaluate the movement patterns and hot-spots of billfish habitat-use in emerging recreational fishing grounds of northern Australia using pop-off satellite archival tags.
3. To conduct a pilot study evaluating the feasibility of tagging billfishes with pop-off satellite archival tags,internally and externally implanted acoustic tags for long-term monitoring of billfish residency and site fidelity on fishing grounds.
4. To collect tissue samples from northern Australia for later analysis in a separate project examining the genetic population structureand trophic ecology of billfish (Sailfish and Black Marlin)
5. To engage recreational fishers in citizen science evaluation of billfish movements and increase growth and economic development of sustainable billfish fisheries in northern Australia through a top end billfish sprint and fisher education.