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- Objectives
- To develop a larval or early-juvenile growth index for yellowfin tuna in the Panama Bight which might prove useful as an index of recruitment strength of yellowfin in the EPO
- Background
- Growth rate variability in the larval and juvenile stages of pelagic marine fishes is substantial, and has strong potential to influence mortality patterns during pre-recruit life stages
- Previous research by the Early Life History group has identified some local correspondence in the Panama Bight between high growth rates/densitydependence in growth of yellowfin larvae and recruitment estimates for yellowfin
- Quarterly or seasonal nightlight surveys of early-juveniles in the Panama Bight are recommended at the Achotines Laboratory, with aging analysis conducted for growth rate estimation and comparison to quarterly recruitment estimates for yellowfin
- Relevance for management
- The development of a larval or early-juvenile growth index is promising as a forecasting tool for assessing yellowfin recruitment patterns.
- Duration
- 4 years
- Workplan and status
- June 2023-December 2024: Conduct quarterly or seasonal nightlight surveys of yellowfin at the Achotines Laboratory
- January 2023-June 2024: Conduct otolith aging analysis on field-caught fish
- Analyze and compare growth data and recruitment estimates for yellowfin, and complete manuscript and submit to scientific journal
- Deliverables
- Presentations for SAC-09, SAC-10, SAC-11 and SAC-12
- Publication of results in a scientific journal
- Updated date: 01 Mar 2023
- Progress summary for the reporting period
- Analysis of in situ growth of yellowfin larvae and early-juveniles in relation to ocean temperature, availability of forage, larval density and availability of potential predators in nursery grounds in the Panama Bight, determined from past at-sea surveys at the Achotines Laboratory, is continuing during 2023.
- Challenges and key lessons learnt
- Funding has not yet been secured for the at-sea surveys and subsequent analyses necessary for the completion of the growth index analysis, but expansion of analysis of past in situ growth sampling is continuing in 2023.
- Presentations:
- SAC-09 (May 2018)
- 42nd Larval Fish Conference (June 2018) and 43rd Larval Fish Conference (May 2019)
- SAC-12-15 Review of research at the Achotines Laboratory