An accurate history of catch is an important input into the assessment of toothfish stocks, and uncertainty or bias in the amount of catch from an area must be taken into account in the assessment of a stock.
In 2013, Korea held a workshop on the anomalous CPUE data reported from some Korean vessels in data-poor exploratory fisheries (Delegation of Korea 2013). That paper requested that the data be analysed for the development and testing of plausible hypotheses to account for its inherent patterns.
One plausible hypothesis is that the catches were not reported proportionally from the areas where they were taken. For the purposes of developing an alternative catch history for these SSRUs, we use these data regarded as anomalous, along with that from other vessels fishing in the same area and season to illustrate a method for re-adjusting catches that may be area-misreported. We do this by using a standardised CPUE from these vessels to develop an estimate of the amount of catch that could plausibly be area-misreported on these vessel trips across the areas fished.
This allows the calculation of possible alternative catches in areas where reports may not reflect catches. In illustrating this approach to the vessels with anomalous CPUE, we can develop alternative catch histories that can be used to assess the sensitivity for assessments of toothfish.