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  4. Improve indices of abundance based on longline CPUE data
Proyeto H.1.d - Improve indices of abundance based on longline CPUE data

01 jun. 2018 - 31 dic. 2019

  • Improve the yellowfin and bigeye indices of relative abundance from longline data
  • Determine methods to identify targeting in longline fisheries
  • Develop spatio-temporal models for creating indices of relative abundance from longline data
  • Develop appropriate longline length composition data for the index of abundance and for the catch
  • Indices of relative abundance derived for longline CPUE data are the most important piece of information in the bigeye and yellowfin stock assessments
  • Only the Japanese data are currently used to create these indices
  • The characteristics, tactics, and spatial distribution of the fishery have been changing over time
  • The same length composition data is used for the index and for the catch, but these could differ
  • New methods, such as spatio-temporal modelling, have been developed and should be used in the creation of the indices
Importancia para la ordenación
The indices have direct impact on the stock assessment and any improvements in the indices will directly improve the management advice for bigeye and yellowfin
18 months, starting June 2018
Plan de trabajo y estatus
  • June-Dec 2018: Evaluate the data available in the IATTC database and implement the spatio-temporal models
  • Jan-Feb 2019: Hold a one-week workshop to discuss approaches to resolve issues in using the longline CPUE data
  • May-June 2019: Hold a two-week working group to analyze the data (not funded)
Colaboradores externos
  • NRIFSF, Japan
  • Invited speakers
  • Workshop report
  • Working group report (not funded)
  • Indices of relative abundance
  • Project report to SAC
Fecha actualizada: 01 abr. 2021
Resumen de los avances en el periodo del informe
  • Preparations for the workshop included:
    • Provision of operational-level longline data for main distant-water longline fleets
    • Visits by Japanese (Dr. Keisuke Satoh) and Korean (Dr. Sung-Il Lee) scientists to work with the staff on analyses
    • Visit by external expert (Dr. Simon Hoyle, supported by ISSF).
  • A workshop was held on February 2019: 23 participants, including 7 invited speakers
  • The work continued after the workshop and the context of the project H.1.1
Retos y principales lecciones aprendidas
  • The operational data essential for improving the assessment are not permanently available to the staff.
  • Matching size-composition and operational data proved difficult, and is not yet completed, the indices were obtained by modelling data aggregated into a 1° latitude by 1° longitude
  • The additional workshop needed to finalize the work (Project H.1.e) is not currently funded.
  • Materials for the workshop
  • Presentation at SAC-10
The work related to this project continued in Project H.1.e