IOTC Albacore Management Strategy Evaluation

This site hosts the materials for the Management Strategy Evaluation (MSE) process for Indian Ocean albacore tuna (Thunnus alalunga), managed by the Indian Ocean Tuna Commission (IOTC).

The MSE tests candidate management procedures against a range of plausible operating models to evaluate their performance against management objectives under uncertainty.

The initial work on the MSE framework and analysis, including conditioning of the Base Case and Robustness Operating Models (OMs), was conducted by R. M. Hillary and I. Mosqueira (see Background & Reference Materials below).

In 2026, Blue Matter Science was contracted to continue the work on the MSE. The MSE analysis uses the iotcALB R package, developed for this purpose and built on the openMSE framework.

Materials

• Trial Specifications Document: the operating models, management procedures, and performance metrics used in the MSE.
• iotcALB R package: R package implementing the MSE analysis, with full technical documentation.

Background & Reference Materials

Operating Model Conditioning Methodology

1. Conditioning IOTC Albacore OMs using the ABC approach

MSE Progress Reports

1. Progress of the Indian Ocean Albacore MSE( 2026)

2. Technical development of Management Strategy Evaluation for Indian ocean albacore tuna: 2025 progress report and current status( 2026)

3. Simulation testing of management procedures for Indian ocean albacore tuna based on ABC operating models: report on progress (2025)

Repository Structure

The iotcALB repository is organised as follows:

Directory / File	Purpose
R/	Package functions and objects
analysis/	Analysis scripts that run the MSE (import OMs, run simulations, apply MPs, summarise results)
data/, data-raw/	Conditioning output and other data bundled with the package
objects/	Saved R objects produced by the analysis scripts (OM/, Hist/, etc.)
tsd/	Quarto source for the Trial Specifications Document
homepage/	Quarto source for this website

Key package components

Functions

• ImportOM(): converts MCMC conditioning output into a multi-stock, multi-fleet MSEtool OM object (quarterly, sex-structured, 6 fleets)
• ValidateOM(): validates OM dynamics against the ABC conditioning model output

Datasets

• CondData_OM5a, CondData_OM5b, CondData_OM6b: ABC conditioning model output containing MCMC-derived variables for the OM5a (SW CPUE), OM5b (base case, NW CPUE), and OM6b (1% effort creep robustness) operating models;
• StockObjectList: MSEtool::Stock objects (Female, Male) with seasonal age structure and length, weight, maturity, and fecundity schedules
• albMSE_Biology: raw biological schedules (length, weight, maturity at annual age and season) used to build StockObjectList
• albMSE_Data: observed catch and CPUE data as an MSEtool::Data object, for use with candidate management procedures

Analysis workflow

analysis/01-import-OMs.R   import conditioning output → OM objects → objects/OM/
                           simulate historical period  → Hist objects → objects/Hist/