Latest Stock Assessment

Details of the latest assessment of southern bluefin tuna (SBT), including updated fishery indicators, are available from the report of the Thirty-First meeting of the CCSBT Scientific Committee:

• Report of the Thirty-First Meeting of the Scientific Committee (3.0 MB).

A brief report on the Report on Biology, Stock Status and Management of Southern Bluefin Tuna is available at:

• Attachment 8 of the Report of the Thirty-First Meeting of the Scientific Committee (1.1MB).

The next full stock assessment for southern bluefin tuna is scheduled to be conducted during 2029.

Summary of the Latest Assessment

The Thirty-First Meeting of the Scientific Committee noted from the 2026 full stock assessment that:

• The stock, as indicated by relative Total Reproductive Output (TRO), is estimated to be 28% (21-37%; 95% credible interval) of TRO₀;
• Stock status has continued to improve and is well above the low point reached in the 2000’s; 
• The stock is at approximately 99% (63-159%; 95% credible interval) of the level estimated to produce maximum sustainable yield (MSY);
• Stock status has improved since the previous stock assessments conducted in 2023 which indicated that relative TRO was at 23% (21-29%) of TRO₀; and
• The fishing mortality rate is at approximately 55% (28-81%; 95% credible interval) of the level associated with MSY.

Table 1: Southern Bluefin Tuna summary of 2026 assessment of stock status.

¹ Values in parentheses are 10th  and 90th percentiles.

² TRO is the total reproductive output summed over all age classes weighted by their relative individual contribution to reproduction.

³ B10+ is the biomass of fish aged 10 years and over.
 

Summary of indicators

Overall results from a review of indicators in 2026 were positive. Most of the CPUE indicators have increased in recent years except for Japanese age 3, Taiwanese age 4 and New Zealand domestic standardised CPUE. Related to information on recruitment monitoring, it was noted that dominant catches of the Australian purse seine fishery (now about 70% of Australia’s total catch) have shifted from age 3 to age 2.

Annual Review of implementation of the CCSBT Management Procedure

At its 2025 meeting, the ESC used the adopted Management Procedure (MP) to calculate a recommended TAC for the period 2027-2029. 

At its 2026 meeting, following the process to examine exceptional circumstances, the ESC concluded that the high CPUE estimate for 2025 constitutes exceptional circumstances, but because of the positive CPUE trend, agreed that the risks to the SBT stock are low. The ESC consequently agreed not to amend its advice on the recommended global TAC for 2027-2029 of 23,647 t/year, which is a 3,000 t (maximum) increase from the 2024-2026 TAC.