Consideration of Exceptional Circumstances for the Bigeye Tuna MP 2022

The IOTC has adopted a management procedure (MP) which will be used to recommend the Total
Allowable Catch (TAC) of bigeye tuna in the Indian Ocean. As part of the MP schedule, the
Commission has adopted an annual review of evidence for exceptional circumstances that could
make the implementation of the TAC advice risky to the stock or fishery.
The Exceptional Circumstances Guidelines specify a three-stage process: (i) examining evidence for
exceptional circumstances, (ii) determining severity and impact, and (iii) recommending any
management or research action that should be taken. A wide range of information is reviewed to
examine if there is evidence for exceptional circumstances, e.g., the data inputs to the MP,
changes in the knowledge of stock or fishery uncertainties against which the MP was tested, and
implementation of MP TAC advice.
Changes in the data used in the CPUE standardisation, a new growth curve and an alternative
natural mortality scenario used in the 2022 stock assessment models were items identified as
potential exceptional circumstances for the 2022 bigeye MP. Severity and impact are considered
low for these items and, therefore, no research or management action on TAC is recommended.
The Exceptional Circumstances Guidelines (IOTC–2021–SC24 Appendix 6A) provide a scientific
process for developing appropriate management responses to exceptional circumstances and,
hence, provide transparency in TAC decision making by the Commission.