A management procedure (MP) is a pre-agreed set of rules that can specify changes to the total allowable catch (TAC) based on updated monitoring data. From 2002 to 2011, the CCSBT conducted extensive work to develop an MP in order to guide its global TAC setting process for southern bluefin tuna. The CCSBT tested a variety of candidate MPs with the aid of an operating model of the fishery that simulated the characteristics of the SBT stock and fishery. The candidate MPs were tested against a range of uncertainties so that a robust procedure could be identified.
An MP, known as the “Bali Procedure”, was recommended by the CCSBT’s Scientific Committee (SC) in July 2011. The Bali Procedure was used to guide the setting of the global SBT TAC for the fishing years from 2012 to 2020 inclusive and it presided over the rebuilding of the stock from approximately 5% of the original spawning biomass in 2010 to approximately 20% in 2020, which is the CCSBT’s interim rebuilding target.
The CCSBT developed a new MP to guide the setting of TACs for 2021 and onwards. The new MP is known as the “Cape Town Procedure” and incorporates new data series and a new rebuilding objective. The new data series comprise changing the recruitment monitoring series from an aerial survey of juveniles to estimates of two-year old abundance from a gene tagging program and incorporating spawning stock estimates from close-kin mark-recapture. The Cape Town Procedure has recommended the global SBT TAC for 2021 to 2023 inclusive and has the following main management parameters:
- The MP is tuned to a 50% probability of achieving a biomass level of 30% of the original spawning stock biomass by 2035;
- The MP is also designed to achieve the original objective of the Bali procedure: i.e. a 70% probability of rebuilding the stock to the interim rebuilding target reference point of 20% of the original spawning stock biomass by 2035;
- The minimum TAC change (increase or decrease) is 100 tonnes;
- The maximum TAC change (increase or decrease) is 3,000 tonnes;
- The TAC will be set for three-year periods; and
- The national allocation of the TAC within each three-year period will be apportioned according to the Resolution on the Allocation of the Global Total Allowable Catch.
The technical specifications of the Cape Town Procedure are available from Attachment 8 of the Report of the 25th Meeting of the Scientific Committee. The specifications contain the following elements, some of which are not technical in nature:
- Introduction (not technical);
- Non-Technical Summary of the Cape Town Procedure (not technical);
- Specification of the population model and HCR used in the MP;
- Data analysis specification for the Gene-tagging abundance estimates used in the MP;
- Specification for the Close-Kin Mark-Recapture data used in the MP;
- Specification of Standardised CPUE for the MP; and
- Metarules for the Cape Town Procedure (not technical).