Latest Stock Assessment

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

• Report of the Twenty-Eighth Meeting of the Scientific Committee (3.4 MB).

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

• Attachment 10 of the Report of the Twenty-Nineth Meeting of the Scientific Committee (0.8MB).

The next full stock assessment for southern bluefin tuna is scheduled to be conducted during 2026.

Summary of the Latest Assessment

The Twenty Eighth Meeting of the Scientific Committee noted from the 2023 full stock assessment that:

• The stock, as indicated by relative Total Reproductive Output (TRO), is estimated to be 23% (21-29%) of TRO₀;
• The stock remains below the level estimated to produce maximum sustainable yield (MSY);
• Stock status has improved since the previous stock assessments conducted in 2020 which indicated that relative TRO was at 20% (16-24%) of TRO₀;
• The fishing mortality rate is below 50 % of the level associated with MSY; and
• The stock has been rebuilding by approximately 5% per year since the low point in 2009.

Table 1: Southern Bluefin Tuna summary of 2023 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

A review of indicators in 2023 shows little overall change since the previous review. 

• Age 1 recruitment indices have decreased somewhat in recent years, but recruitment levels are above those experienced from 1980 to the early 2000s and gene-tagging based estimates of age 2 recruitment are robust. 
• There are consistent positive trends in the age-based longline CPUE estimates across a number of fleets. 
• The detection rate of parent-offspring pairs from the most recent close-kin mark-recapture data is consistent with an increase in adult abundance.

Annual Review of implementation of the CCSBT Management Procedure

At its 2022 meeting, the ESC used the adopted MP to calculate a recommended TAC for the period 2024-2026. The recommended TAC is 20,647 tonnes which is an increase of 3,000 tonnes, the maximum allowed under the adopted MP. 
At its 2023 meeting, the ESC followed its process for examining exceptional circumstances and, finding none, confirmed its advice for the TAC of 2024-2026.