- Objectives
- Determine the feasibility of echo-sounder buoy data to be used for developing alternative abundance indices for tropical tuna.
- Develop preliminary catch-independent abundance indices for tropical tunas.
- Evaluate the usefulness of these indices to inform and complement traditional stock assessment and other projects of interest for the Commission (e.g. MSE, habitat models).
- Explore the future availability of echo-sounder buoy data in the region for scientific purposes.
- Develop strategies and plans to improve the robustness of results and help interpretation.
- Recommend new feasible technological developments to buoy manufacturers.
- Background
- Fishing efficiency of the tropical tuna purse seines are rapidly evolving due to technology and effort creep and obtaining reliable CPUE is challenging task.
- New technologies also provide new opportunities for science. Echo-sounder buoys have the potential to daily sample thousands of FADs in a systematic and non-invasive manner.
- This information could be used to develop alternative abundance indices for tunas using catch-independent data.
- Other t-RFMOs (e.g. ICCAT) have explored the use of buoy derived abundance indices in their recent stock assessments. Those indices were developed by AZTI.
- The good relationship with AZTI, OPAGAC and Cape Fisheries granted access to historical satellite-linked echosounder buoy data used by the fleet in the Pacific Ocean
- Relevance for management
- This project will advance our understanding of tropical tuna species population dynamics and stock status. Project activities will support several objectives for increasing the sustainability of exploited resources described in the SSP as well as will advance on the use of new technologies and data sources to improve decision-making.
- Duration
- 12 months, extended to 36 due to COVID-19
- Workplan and status
- 2020 – data extraction and preparation. Run standard procedures and methodologies to obtain preliminary indices. Start discussing and exploring new approaches and uses of the data.
- 2021 – an AZTI researcher will visit the IATTC headquarters and preliminary indices will be updated. Preparation of dissemination materials and recommendations.
- External collaborators
- AZTI Foundation, OPAGAC, Cape Fisheries, ISSF
- Deliverables
- A series of alternative abundance indices for the three species of tropical tuna using catch-independent information.
- Dissemination material, including documents and presentations for the Scientific Advisory Committee and the workshop on developing alternative abundance indices for tropical tuna that ISSF is organizing, likely, in 2021.
- Updated date: 01 May 2024
- Progress summary for the reporting period
- Several online meetings have been conducted with collaborators in 2020-2022. A research stay of 3 months has been conducted by an AZTI researcher in 2023. The research stay helped streamline the work and the methodology and trained some new IATTC staff members on the process and the data. In addition, the feasibility of echo-sounder buoy data to be used for developing alternative abundance indices for tropical tuna has been determined.
- A series of preliminary catch-independent abundance indices for tropical tunas have been produced.
- A list with research ideas, approaches and plans to improve the robustness of results and help interpretation has been produced and updated every year, and the team will work on them in the future.
- The buoy derived abundance index for skipjack has been used in the interim assessment conducted in 2022 and will be tentatively explored for 2023 and 2024 yellowfin, bigeye and skipjack assessments.
- Two additional BREP proposals have been prepared to improve data use and interpretation of both historic and future data.
- Access to historic data is being negotiated with several industry partners
- Challenges and key lessons learnt
- Several additional tasks have been identified to improve the model output. A list of the ideas to be explored in 2021-2024 are described in FAD-05-INF-E, FAD-06-03 and FAD-07-03 and FAD-08-02.
- Access to high-resolution buoy data, including biomass information, is key to advance the scientific advice but has also been identified as problematic and confidential by some fleet owners.
- The staff does not require real time data and guarantees that all the IATTC confidentiality and privacy rules are followed, if access to historic data is granted. The present project, where data has been provided by OPAGAC and Cape Fisheries in a voluntary basis, is a good example of success. Other voluntary agreements are currently being explored by the IATTC staff, while officially recommending the reporting of historic high-resolution buoy data.
- The buoy derived abundance index was proven to be useful to improve skipjack assessment in 2022 and its use will be explored for the 2023 yellowfin and bigeye tuna assessments.
- Presentations:
Reports:
- FAD-05-INF-E Tropical tuna biomass indicators from echosounder buoys in the EPO
- FAD-06-03 Tropical tuna biomass indicators from echosounder buoys in the EPO
- FAD-07-03 Updated biomass indicators from echosounder buoys
- FAD-08-02 Updated biomass indicators from echosounder buoys
- SAC-13-07 Interim skipjack assessment
Other products
- A series of preliminary buoy-derived abundance indices for tropical tuna species for internal discussion and use in the skipjack interim assessment in 2022, as well as preliminary indices for the 2024 yellowfin, skipjack and bigeye assessment.
- Comments
- Because of the pandemic, the research stay of the main-researcher in La Jolla was postponed to 2023. The research stay was successful and help the IATTC staff better understand the process to derive the buoy index.
- A workshop on echo-sounder buoy data is expected to be organized by ISSF in 2023/2024, where the results and methods of this project will be presented and discussed.
