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Management Procedure Evaluation Status
• Management Procedure (MP) evaluation is being pursued in the strict sense (i.e. as in the International Whaling Commission and Commission for the Conservation of Southern Bluefin Tuna), in which the data to be input to the MP, the analysis, and the Harvest Control Rule (HCR) are all defined in advance and simulation-tested together.
• The yellowfin reference set Operating Model (simulator) is being iteratively developed in line with requests from the IOTC technical working parties (WPTT and WPM) and the stock assessment process.
• Funding to continue the scientific and technical support for two years (August 2021 – June 2023) is being sought from the Australian Government.
• The latest iteration of the Operating Model was fit with data up to and including 2017. There are now catch observations available for 2018 and 2019, which are adopted for the first two years of the MP evaluation testing. The Operating Model was found to be unrealistically pessimistic, because most or all of the simulations could not extract the observed 2019 catch (Figure 1). The stock status or productivity estimates for the population are too pessimistic and/or the spatial distribution of fish is not sufficiently realistic to allow the removal of these catches. This indicates a critical failure of the predictive capacity of the Operating Model. The Operating Model and stock assessment are afflicted by similar problems, that need further investigation before MP evaluation results can be considered meaningful. See IOTC-2021-WPM12(MSE)-03 for more detail. A full yellowfin stock assessment with a broad collaboration of IOTC scientists is scheduled for WPTT 2021.
