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Project N.1.a - Analyze EPO bycatch data to assess the influence of environmental drivers on catches and vulnerability

01 Jan 2018 - 31 Dec 2018

Program(s) in charge: Ecosystem & Bycatch Program
To better understand environmental drivers that might be responsible for increasing the vulnerability of non-target species to being caught in EPO fisheries, and devise management measures that may reduce their vulnerability to capture (e.g. space-time closures).
  • Each year the IATTC reports catch estimates for non-target species in its Fishery Status Report.
  • Nominal catches of bycatch species may not fully explain the magnitude of interannual variability in fishing effort, since environmental factors may drive key processes such as recruitment.
  • To improve our understanding of processes affecting catches in the EPO purseseine fishery, we assess ecosystem components including catches of vulnerable shark species in relation to variability in oceanographic conditions and life history characteristics.
Relevance for management
Catch prediction models to better manage data-poor species
12 months
Workplan and status
  • Jan-Apr 18: exploratory analyses of IATTC observer catch data and oceanographic conditions over the past two decades
  • Apr-May 18: present results at the international PICES conference, “Understanding Changes in Transitional Areas of the Pacific” and the 69th Tuna Conference
  • Jun-Jul 18: Prepare a manuscript for publication in a scientific journal
  • Reporting of bycatch estimates in the Ecosystem Considerations report
  • Manuscript that contributes to IATTC’s ecosystem approach through evaluation of potential environmental drivers influencing catches in the EPO purse-seine fishery and relationships between environment and life history characteristics
Updated date: 01 May 2021
Progress summary for the reporting period
  • Bycatch estimates for 2019 documented in the Ecosystem Considerations report
  • Oceanographic data (SST, chlorophyll-a, etc.) and environmental indices (ONI, PDO, others) included in the Ecosystem Considerations report
Challenges and key lessons learnt
Models are now being revised and run with target species to ensure their reliability before being applied to other species of bycatch
  • PICES International Symposium on Understanding Changes in Transitional Areas of the Pacific (April 2018)
  • 69th Tuna Conference (May 2018)
The Ecosystem Group has been collaborating with the Bycatch and Gear Technology Group to determine an appropriate model to apply to bycatch species.