Program(s) in charge: Ecosystem & Bycatch Program
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- To obtain morphometric relationships for priority species (e.g., tunas, billfishes, elasmobranchs, other large fishes) and to opportunistically collect biological samples
- Length-weight (L-W) relationships can vary markedly in space and time and can greatly influence stock and risk assessment models outcomes. L-W relationships for tunas are outdated (e.g., yellowfin: 1986, bigeye: 1966 and skipjack: 1959) or inadequate for many priority species (see SAC-13-11, SAC-09-12).
- Catch estimations are also affected by imprecise and/or outdated L-W relationships used to convert catch in numbers to weights and vice versa.
- Basic life history data for assessment models are absent or inadequate for most bycatch species
- Size composition of fish and fishing grounds differ significantly between longline (LL) and purse-seine (PS) fisheries (e.g. see IATTC-98-01); this study would initially focus on a subset of longline and PS vessels to develop sampling protocols.
- Simultaneously, discussions between IATTC and CPCs on improving data provision (see SAC-12-09, SAC-12-16) would occur for possible expansion to other vessels and areas in coordination with the other data collection programs in the EPO (e.g. SAC-13-12).
- Relevance for management
- Evidence of structure in EPO stocks of tuna species has been shown from extensive tagging studies, meristic and morphometric analyses, and genetic work, and future assessment will be executed accounting for putative stock structure. Changes in catch estimations can initiate a response in management rendering improvements to conversion factors an essential component for providing better catch estimations. Collection of morphometric and biological samples (e.g. otoliths, tissues, stomachs), will provide information to refine key life history information and to develop improved models for tunas and other prioritized species, thereby advancing scientific advice for decision making.
- 24 months
- Workplan and status
- Jun-Dec 2022: Internal staff discussions to identify target species and tasks, review and identify sampling opportunities across EPO fisheries. Reach out to CPCs and relevant stakeholders to identify collaborative sampling opportunities. As needed, collaborate with the industry to gain support, develop sampling design, data forms and databases, purchase equipment, initiate/refine protocols for LL, revise and complete protocol for PS vessels, develop a storage protocol for IATTC regional offices and imports/exports following strict international protocols, engage in conversations during workshops to improve data collection processes and identify other potential fisheries observers’ program where sampling will be executed. Develop a research proposal for implementing a feasibility study in the EPO for prioritized species (Phase 2).
- External collaborators
- Fishing industry and CPCs, CITES offices in corresponding countries
- Report to SAC-14 in 2023, including a potential research proposal