Individual Vessel Limit (IVL) pilot study

Project B.3.a - Individual Vessel Limit (IVL) pilot study

01 Jul 2022 - 31 Dec 2022

Program(s) in charge: Stock Assessment Program

Funded

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Theme 1. Data collection for scientific support of management
Goal B. Conduct a review of current IATTC/AIDCP data collection programs, identify and prioritize opportunities to improve data quality and expand data types and coverage
Target B.1. Evaluate and improve data collected by the purse-seine On-Board Observer Program for scientific research

Objectives

Develop sampling designs for estimating well-level and trip-level catch composition to be used in the IVL enhanced port-sampling program in 2023-2024.

Background

At the 98th Meeting of the IATTC, the Commission established an IVL program for bigeye tuna catches (Resolution C-21-04), which is to include a special portsampling program (“IVL enhanced port-sampling program”) for trips considered to have caught a significant amount of bigeye tuna.
To implement the IVL enhanced port-sampling program, the sampling protocol of this program needs to be tailored to estimation of well-level and trip-level catch composition.
The sampling protocol of the current IATTC port-sampling program is not appropriate for this task because it was designed for estimation of fleet-level catch composition and was based on results of studies conducted prior to the expansion of the fishery on fish-aggregating devices in the 1990s.
Given this, as outlined in SAC-13 INF-E, an IVL pilot study is planned for the second half of 2022 to: 1) collect extensive well sampling data for a simulation study to test sampling designs for well-level and trip-level catch composition estimation; and, 2) field-test the best sampling designs from (1) to identify and mitigate any logistical issues in advance of the initiation of the IVL enhance port-sampling program in 2023.

Relevance for management

Development of sampling designs for estimation of catch composition for individual vessel trips is essential to the success of the IVL enhanced port-sampling program and to the IVL Program, more generally.

Duration

6 months

Workplan and status

July – October 2022: collect extensive well sampling data and conduct a simulation study to test sampling designs.
November – December 2022: Field-test sampling designs developed in the simulation study, to identify and mitigate any logistical issues.

External collaborators

Government of Ecuador (4 samplers to be provided in-kind)

Deliverables

Reports for the SAC and the Commission; publications in peer-reviewed journals.