Patagonian toothfish have been tagged during commercial fishing and research activities adjacent to Heard Island and the McDonald Islands (HIMI, CCAMLR Division 58.5.2) since 1998, with 27,679 toothfish tagged and released, and 4925 recaptures. The data derived from this program has been valuable in estimating key population parameters for toothfish in this region, and have been used in the 2014 stock assessment (Ziegler, et al, 2014) in various ways including:
- local abundance estimators;
- natural mortality;
- movement rates;
- growth;
- stock structure; and
- estimation of q of the trawl surveys;
However, due to the spatial pattern of releases, toothfish movement, and recapture effort, it is unlikely that these data can currently be used in an unbiased manner to estimate stock abundance. Developing spatially explicit models that account for fleet dynamics, and phenotypic variability in post-release behaviour, remains an issue for all assessments incorporating tagging data and, in particular, in Division 58.5.2. Plans to develop such spatial models, as well as increasing tagging rates and attempting to spread the release and recapture effort, are likely to rapidly improve the utility of this data for future assessments.