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Project L.2.d - Pacific-wide vulnerability assessment of pelagic shark species caught as bycatch in tuna fisheries

01 Sep 2021 - 31 May 2023

Program(s) in charge: Ecosystem & Bycatch Program
  • In collaboration with SPC, use the EASI-Fish ERA approach to undertake a Pacific-wide vulnerability assessment of shark species caught as bycatch in tuna fisheries managed by the IATTC and WCPFC
  • To identify the most vulnerable species using traditional biological reference points
  • In 2021, SPC developed species distribution models for all shark bycatch species caught in WCPFC tuna fisheries with the intent to undertake a vulnerability assessment using the EASI-Fish approach.
  • Many of the species examined by SPC have a Pacific-wide distribution and therefore cross the jurisdictional boundary between the IATTC and WCPFC.
  • In 2022, SPC will conduct the first shark assessment using EASI-Fish. Therefore, in order to better model the true extent of fishery impacts on cross jurisdictional stocks, the SPC and IATTC staff will collaborate in the assessment.
Relevance for management
EASI-Fish assessments can transparently identify vulnerable species by using well established biological reference points, thus minimizing the chances of incurring false positives that may require improper and costly management actions to be taken. Many ERAs have previously been undertaken on individual fisheries or jurisdictions, thus underestimating true fishery impacts on shared stocks. By undertaking a Pacific-wide EASI-Fish assessment for shared stocks both the IATTC and WCPFC will better understand the true extent of fishery impacts on assessed stocks, and be able to identify species of high vulnerability in order to subject to further assessment or management as required.
12 months
Workplan and status
  • Sep 2021-June 2022: complete Pacific-wide EASI-Fish assessment in collaboration with SPC and identify vulnerable species.
  • Aug 2022: present assessment results at WCPFC SC in 2022.
  • May 2023: present assessment results at SAC-14 in 2023, if required.
External collaborators
  • Paper and oral presentation at SAC-14 and WCPFC SC, if required.
  • A scientific journal publication.
Updated date: 01 May 2023
Progress summary for the reporting period
  • July-Sept 2021: Collated available effort and shark interaction data for 8 fisheries in the EPO from IATTC databases, 5 fisheries in the WCPO from SPC databases, and publicly available publications
  • Sept 2021-Mar 2022: Collated available biological information for ~50 shark bycatch species shared with the WCPO area from IATTC and SPC databases.
  • Jan-Feb 2022: SPC developed SDMs for ~50 species using an ensemble approach from 4 SDM algorithms using all data from the Pacific Ocean.
  • June 2022: Species to be selected for assessment in EASI-Fish with consultation with IATTC and WCPFC stakeholders.
  • Aug 2022: Discussions between SPC and IATTC staff revealed a technical issue in SDM development that posed a problem for undertaking a Pacific-wide assessment for shark species. The issue pertains to habitat preferences being modelled for the entire Pacific, but relative regional differences in the relationship strength between presence and environmental variables resulted in the EPO probability of occurrence being underestimated for several species. Staff are currently discussing how to resolve this issue by potentially creating an ensemble of subregions to develop a basin-wide SDM. Similarly, SPC-IATTC are in conversations to put together a working group on best practices for SDMs.