Factors that may influence the accuracy of abundance estimates from CCAMLR tag-recapture programs for Dissostichus spp. and best practice for addressing bias
The Lincoln-Petersen equation, the simplest form of an abundance estimator using tag-recapture data, was used to identify processes that may introduce bias into abundance estimates derived from tag-recapture programs. The methods that have been used in CCAMLR tag-recapture programs to mitigate such biases, or to account for their effects in stock assessments for Dissostichus spp. are also summarised. In nearly all cases, examples of at-sea or model-based approaches are available from established Dissostichus spp. tag-recapture programs to reduce these biases. Estimates of post-capture mortality, tag-detection rates and, where it occurs, post-release depredation rates are a priority for new assessments that use tag-recapture data. Due to the complexity of toothfish movements throughout their life cycle, as well as the spatial structure of release and recapture efforts by fishing and research vessels, development of spatially explicit modelling approaches is also an important next step for Dissostichus spp. assessments that use tag-recapture data.