Atlantic Bluefin Tuna MSE
(Thunnus thynnus)
Generated by ChatGPT on 15 Feb 2026
Overview
Atlantic bluefin tuna exhibits complex dynamics involving two stocks
(eastern and western), characterized by long-distance movements and
mixed-stock fisheries. Management Strategy Evaluation (MSE) for Atlantic
bluefin tuna, incorporating stock mixing between the two stocks, has
been under development since at least 2014. Following substantial
efforts by both the SCRS and the Commission, a Management Procedure (MP)
was adopted in 2022 (Rec. 22-09). Total Allowable Catches (TACs) for both stocks have been set basically based on this MP since 2022.
The Commission adopted the Exceptional Circumstances Protocol (ECP) in 2023 (Rec. 23-07, Annex 4), which requires an annual evaluation of Exceptional Circumstances (ECs) by the SCRS. No ECs were declared in 2023 or 2024. In 2025, the SCRS was unable to reach consensus on whether ECs had been invoked
The SCRS plans to conduct a stock status assessment and review the Operating Models (OMs).
| OMs Developed in 2014-2021 |
MP Adopted in 2022 |
ECP adopted in 2023 |
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| Recondition in 2028 |
MP since 2022 | ECs evaluation No ECs in 2023 or 2024 No consensus on ECs in 2025 |
History
A detailed account of the Management Strategy Evaluation (MSE) process for Atlantic bluefin tuna (BFT) is available in the SCRS Reports and in the documents and activity reports of the ICCAT Atlantic-Wide Research Programme for Bluefin Tuna (GBYP). The BFT MSE process was initiated in 2013 with a kick-off meeting held in Gloucester, USA (Anon., 2013). During the development of the Operating Models (OMs), the SCRS began consultations with Panel 2 in 2019 to define operational management objectives, as outlined in Resolution 18-03.
Following the adoption of the OMs in 2021 (Anon., 2021), the SCRS focused on the development and evaluation of Candidate Management Procedures (CMPs) and maintained regular engagement with the Commission to support the adoption process. This engagement was facilitated through intersessional meetings and a series of “Ambassadors webinars,” which were used to communicate MSE results to stakeholders and decision-makers.
In 2023, the Commission adopted the Exceptional Circumstances Protocol (ECP) (Rec. 23-07, Annex 4). These milestones represent the culmination of a decade-long, iterative process to establish a scientifically robust and operationally viable management framework for Atlantic bluefin tuna.
Operating Models (OMs)
The SCRS developed a novel population dynamics model for the Atlantic bluefin tuna OMs that explicitly accounts for stock mixing between the two biological populations. This model integrates multiple data sources, including otolith microchemistry, genetic analyses, and electronic tagging data. The development of this modelling framework required several years of effort, beginning around 2015, and culminating in the adoption of the OMs in 2021. Progress was partly constrained by the need for the SCRS to also conduct full stock assessments for the eastern and western Atlantic bluefin tuna stocks in 2017 (E/W), 2020 (E/W), 2021 (W), and 2022 (E). The adoption of these OMs in 2021 represented a significant milestone in addressing the complexities associated with stock mixing, achieved despite the concurrent demands of multiple assessment cycles.
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| More materials can be found in References | ||
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| Summary | MSE Codes | Shiny App |
Management Objectives
| Stock Status | Safety | Yield | Stability |
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| Prob. >= 60% in green quadrant for both W,E stocks | Prob. < 15% of stock falling below BLIM | Maximize overall catch in both W,E areas | TAC changes between periods +20%/-35% |
Candidate Management Procedures (CMPs)
Seven CMPs were initially developed since 2019, following 2 CMPs were sent to the Commission for their final selection in 2022.
- CMP-BR by Butterworth and Rademeyer (2022)
- CMP-LW by Lauretta et al. (2020)
Management Procedure (MP)
The Commission adopted the BR MP in 2022 (Rec. 22-09, Annex 2).
| The BR MP is an empirical approach that utilizes standardized abundance indices as its primary input. These indices are initially standardized for magnitude and subsequently aggregated using a weighted average of ten indices representing both the eastern and western Atlantic areas. The resulting composite index is then smoothed over three years to reduce the influence of observation error and interannual variability. The Total Allowable Catches (TACs) are determined by applying a fixed harvest rate to the estimated abundance, as derived from the aggregated and smoothed indices. |
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| Rec. 22-09 Annex 2 |
Exceptional Circumstances (ECs)
The Commission adopted the Exceptional Circumstances Protocol (ECP) in 2023 (Rec. 23-07 Annex 4).
The SCRS have evaluated ECs annually since 2023 ,and no ECs were declared in 2023 or 2024. In 2025, although the combined indices did not trigger EC, the SCRS was unable to reach consensus on whether the Close-kin Mark Recapture (CKMR) new results warranted triggering EC.
Principles of ECs a: When there is evidence that the stock and/or fishery dynamics are in
states not previously considered to be plausible in the context of the
management strategy evaluation (MSE); |
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| EC Protocol: Rec. 23-07, Annex 4 |
References of Atlantic Bluefin Tuna
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| Year | Ref | Document |
|---|---|---|
| 2025 | Capacity building | How to efficiently craft a management procedure |
| 2025 | Capacity building | Management Procedures and Management Strategy Evaluation: A Brief Guide for Managers |
| 2025 | Capacity building | Management procedures versus traditional fisheries management |
| 2025 | Codes | BFT MSE Codes |
| 2025 | Codes | FLBEIA Code |
| 2025 | Harvest Strategies Glossary | Harvest Strategies Glossary |
| 2025 | IOTC | IOTC MSE capacity building tools |
| 2025 | SCRS/P/2025/009 | Proposal on the ICCAT MSE website by Ad-hoc Sub-group on MSE Communication |
| 2025 | SCRS/P/2025/075 | Evaluation of BFT EC 2025 |
| 2025 | SCRS/P/2025/088 | Bluefin tuna MSE - CKMR and Exceptional Circumstances 2025 |
| 2025 | SCRS/P/2025/111 | ICCAT Bluefin tuna intersessional work on ‘lite-reconditioning’ and retuning incorporating WBFT Close-kin mark recapture |
| 2024 | Capacity building | Assessment of Candidate Management Procedures and Harvest Control Rules for the Western Atlantic Skipjack Tuna |
| 2024 | Capacity building | How is MSE based MPs different from current stock assessment practice? |
| 2024 | Capacity building | HOW TO PUT A MANAGEMENT PROCEDURE TOGETHER |
| 2024 | Capacity building | Management Procedure Elements |
| 2024 | Capacity building | Objective of MSE simulations |
| 2024 | Capacity building | Reference Points & Rules: Managing fisheries for the future |
| 2024 | Capacity building | Restoring Pacific saury to a predictable and productive fishery |
| 2024 | Capacity building | What is an MSE based MP? |
| 2024 | SCRS/P/2024/016 | Design of a next-generation, multi-stock assessment for Atlantic Bluefin tuna that incorporates close-kin mark recapture |
| 2024 | SCRS/P/2024/074 | FLBEIA: A simulation model to conduct Bio-Economic evaluation of fisheries management strategies |
| 2024 | SCRS/P/2024/077 | ICCAT Bluefin tuna Exceptional circumstances provisions |
| 2024 | SCRS/P/2024/078 | MSE Process Scorecard for ICCAT Stocks |
| 2024 | SCRS/P/2024/110 | Close Kin Mark recapture estimates of abundance of Western Atlantic Bluefin Tuna |
| 2024 | SCRS/P/2024/114 | BFT MSE MP re-running and next steps |
| 2024 | SCRS/P/2024/122 | Evaluation of BFT EC 2024 |
| 2023 | Capacity building | Two Tools Can Help Make Ecosystem-Based Fisheries Management a Global Reality |
| 2023 | openMSE | Open Source Software for Management Strategy Evaluation |
| 2023 | SCRS/2023/170 | Updates to indices used by the adopted management procedure for Atlantic bluefin tuna |
| 2023 | SCRS/2023/171 | Exceptional circumstances provisions for the Atlantic bluefin tuna management procedure |
| 2023 | SCRS/2023/172 | Secondary indicators of exceptional circumstances for Atlantic bluefin tuna including stock of origin and electronic tagging data |
| 2023 | SCRS/P/2023/007 | Atlantic Tropical Tunas Management Strategy Evaluation (MSE) |
| 2023 | SCRS/P/2023/008 | Western Atlantic Bluefin tuna Close-Kin Abundance Estimation |
| 2023 | SCRS/P/2023/015 | Close-Kin Mark-Recapture for spawning stock biomass estimation of Northeast Atlantic demersal species |
| 2023 | SCRS/P/2023/022 | Streamlined Approach for Close Kin Mark Recapture in Western Atlantic Bluefin |
| 2023 | SCRS/P/2023/051 | A Review of Reference Points, Objectives, and Performance Standards at tRMFOs |
| 2022 | BFT MSE TSD (final) | Trial Specification Document for BFT OMs |
| 2022 | Capacity building | To Strengthen Fishery Management, RFMOs Should Use Science-Management Dialogue Groups |
| 2022 | SCRS/P/2022/013 | Preliminary CMP results April 2022 |
| 2022 | SCRS/P/2022/014 | AN EXPLOITATION RATE PROPOSAL FOR AN APPROPRIATE MSE PERFORMANCE METRIC RELATING TO FISHING MORTALITY |
| 2022 | SCRS/P/2022/016 | THE 2022 STOCK SYNTHESIS STOCK ASSESSMENT PRELIMINARY RESULTS OF THE EASTERN ATLANTIC AND MEDITERRANEAN BLUEFIN TUNA |
| 2022 | SCRS/P/2022/021 | Updated CMP results |
| 2022 | SCRS/P/2022/038 | BFT Management Strategy Evaluation (MSE) |
| 2022 | SCRS/P/2022/047 | Updated CMP results |
| 2022 | SCRS/P/2022/052 | Updated CMP results |
| 2022 | SCRS/P/2022/059 | CMP results |
| 2021 | Capacity building | Harvest strategies: Fisheries Management for the 21st Century |
| 2021 | Codes | openMSE Code |
| 2021 | SCRS/P/2021/027 | Atlantic bluefin tuna MSE progress |
| 2021 | SCRS/P/2021/045 | BFT MSE Consultant’s update on work since April meeting and an informal meeting in June |
| 2021 | SCRS/P/2021/050 | BFT MSE Consultant’s update on work since July meeting |
| 2021 | SCRS/P/2021/051 | Updated CMP results |
| 2021 | SCRS/P/2021/052 | Status update for the M3 & ABTMSE R Package code review |
| 2021 | SCRS/P/2021/054 | Proposal to develop a dedicated stochastic OM for use in CMP development tuning |
| 2021 | SCRS/P/2021/060 | Projections of Western Atlantic spawning stock biomass under different catches from the west area commencing in 2022 based on the MSE OM grid |
| 2020 | SCRS/P/2020/019 | Atlantic Bluefin tuna MSE Progress and lessons learned to date |
| 2020 | SCRS/P/2020/022 | Preliminary evaluation of a CMP for Atlantic bluefin using MSE (v6.6.12) |
| 2020 | SCRS/P/2020/023 | Western Atlantic Bluefin Tuna Stock Assessment 1950-2018 Using Stock Synthesis: Preliminary Results and Diagnostics with Initial settings |
| 2020 | SCRS/P/2020/024 | Preliminary performance across the 96 OM grid of model-based and empirical CMPs tuned to a subset of 5 operating models chosen via cluster analysis |
| 2020 | SCRS/P/2020/025 | BFT MSE developments 2020 May |
| 2019 | Capacity building | Harvest Strategies: 21st Century Fisheries Management |
| 2019 | ICCAT WS | ICCAT MSE Introductory Workshop in 2019 |
| 2019 | SCRS/P/2019/001 | Preliminary evaluation of a CMP for Atlantic bluefin using MSE |
| 2019 | SCRS/P/2019/003 | Constant exploitation rate candidate management procedures for Atlantic bluefin tuna |
| 2019 | SCRS/P/2019/038 | Preliminary evaluation of a CMP for Atlantic bluefin using MSE (ver 5.2.3) |
| 2019 | SCRS/P/2019/044 | Performance of 2 empirical management procedures tested on ABT MSE version 5.2.3 |
| 2019 | SCRS/P/2019/045 | Report of Activities April - July 2019 for Atlantic bluefin OMs |
| 2019 | SCRS/P/2019/046 | Designing and Testing a Multi-Stock Spatial Management Procedure for Atlantic Bluefin Tuna |
| 2019 | SCRS/P/2019/047 | Additional results of BFT OMs for v5.3.1 |
| 2019 | SCRS/P/2019/049 | OM report for OM_1 and three CVs for the precision of the GOM Larval survey (v5.3.2) |
| 2019 | SCRS/P/2019/062 | Progress on Operating Model Conditioning since St Andrews |
| 2019 | SCRS/P/2019/067 | Progress toward West Atlantic bluefin tuna close-Kin mark-recapture |
| 2018 | BFT TSD | Technical details of some of the CMPs (Appendix 6 in Report of the 2018 ICCAT Bluefin Tuna Species Group MSE Intersessional Meeting) |
| 2018 | SCRS/P/2018/015 | Preliminary evaluation of MPs for Atlantic bluefin using MSE |
| 2018 | SCRS/P/2018/016 | An extremely preliminary evaluation of some empirical management procedures |
| 2018 | SCRS/P/2018/017 | Overview of a MSE reference document: ‘Specifications for MSE Trials’ |
| 2018 | SCRS/P/2018/018 | Improving communication: the key requirement to improve the effectiveness of MSE processes |
| 2018 | SCRS/P/2018/019 | Current state of MSE/HCR Process in ICCAT |
| 2018 | SCRS/P/2018/020 | What makes an MP an MP and an MSE an MSE? |
| 2018 | SCRS/P/2018/021 | Operating model for North Atlantic swordfish (Xiphias gladius) |
| 2018 | tRFMO MSE Glossary | Glossary of terms for harvest strategies, management procedures and management strategy evaluation |
| 2018 | tRFMO MSE meeting | REPORT OF THE 2018 JOINT TUNA RFMO MANAGEMENT STRATEGY EVALUATION WORKING GROUP MEETING (Seattle, USA – 13-15 June 2018) |
| 2018 | tRFMO MSE Working Group | Joint Tuna RFMO Management Strategy Evaluation Working Group |
| 2016 | Capacity building | Harvest Control Rules |
| 2016 | Capacity building | Management Objectives |
| 2016 | Capacity building | Management Strategy Evaluation for Fisheries |
| 2016 | Capacity building | Reference Points |
| 2015 | Capacity building | Harvest strategies |
| 2014 | IATTC SAC-05-10b | MANAGEMENT STRATEGY EVALUATION (MSE) IMPLEMENTATION IN STOCK SYNTHESIS: APPLICATION TO PACIFIC BLUEFIN TUNA |
| 2014 | ICES Journal of Marine Science, 71(2): 195–203 | Implementing harvest strategies in Australia: 5 years on |
| 2003 | North American Journal of Fisheries Management, 23: 349–361 | Targets and Limits for Management of Fisheries: A Simple Probability-Based Approach |
| 1998 | Canadian Journal of Fisheries and Aquatic Sciences, 55(6): 1545–1552 | Recent international agreements and the precautionary approach: new directions for fisheries management science |
| 1996 | FAO | FAO precautionary approach to capture fisheries and species introduction |