Improve the bigeye tuna stock assessment: reduce the bimodal pattern in bigeye tuna assessment results

Project H.1.a-2 - Improve the bigeye tuna stock assessment: reduce the bimodal pattern in bigeye tuna assessment results

01 Jan 2021 - 31 Dec 2024

Program(s) in charge: Stock Assessment Program

Funded

Click to see projects by theme, goal or target:

Theme 3. Sustainable fisheries
Goal H. Improve and implement stock assessments, based on the best available science
Target H.1. Undertake the research necessary to develop and conduct at least one benchmark stock assessment for yellowfin and bigeye tunas

Objectives

Improve the bigeye tuna stock assessment by reducing the bimodal pattern in assessment results

Background

A benchmark assessment was conducted in 2020 with 48 reference models representing several hierarchical hypotheses for the stock. A risk analysis approach was used to weight those 48 reference models to get probabilistic distribution profiles for key management quantities. The main issue with the assessment results is that the probabilistic distribution profiles for both depletion and fishing mortality are bimodal.

Relevance for management

The stock assessment is used to provide management advice for tropical tunas
The duration of recommended seasonal closures is based on risk analyses of bigeye and yellowfin that use the assessment results
Improvements in the bigeye assessment will make the staff’s management advice more accurate and precise

Duration

48 months

Workplan and status

2021: Re-evaluate the natural mortality assumptions
2022: CAPAM workshops on improving the risk analysis approach
2023: CAPAM tuna stock assessment good practices
2023: Re-evaluate model assumptions and present an exploratory assessment (SAC-14-05)
2024: Benchmark assessment

Deliverables

Reports to SAC in 2022, 2023 (SAC-14-05; WSRSK-02) and 2024 (benchmark assessment)