This paper frames a discussion for improving the assessment of toothfish abundance for SSRUs 88.2C–G. We initially provide a characterisation of the fishery and a summary of available tagging and length frequency data. Although 880 tagged fish have been released in this region, only 2 tagged fish have been recaptured. It is likely that the lack of recaptures of tagged fish in this region has been caused primarily by the poor spatial overlap of released tagged fish with subsequent fishing effort.
By drawing on the success of tagging programmes in other CCAMLR fisheries, we develop an approach for improving the spatial overlap of the location of tagged fish and subsequent fishing effort. We identify four main grounds previously fished in SSRUs 88.2C–G. We recommend that in the short term (the next 2–3 years) it be made mandatory for vessels to complete all of their sets inside one or more of these fishing grounds as a condition of fishing in the slope region (SSRUs 88.2C–G). This condition could be relaxed in future years once sufficient tags have been recaptured to carry out an assessment of the stock in this region. We also recommend that the tagging rate in this region be increased to at least 3 tags per tonne in the short term. In addition to improving estimates of abundance a higher tagging rate and more recaptures will also increase information on fish movement within the Amundsen Sea slope which will help reduce uncertainty about the stock identity of toothfish caught in this area.