Quantifying uncertainty in the Chapman mark-recapture estimate of abundance

In New and Exploratory fisheries for toothfish, mark-recapture plays a critical role to estimate biomass in the initial stage of developing an assessment. This short paper describes the use of the R package tagr to obtain Petersen / Chapman estimates of abundance. The package implements a non-parametric bootstrap to obtain confidence intervals from single release tag-recapture data.

We recommend that WG-FSA encourage Members to provide estimates of uncertainty associated with indicative biomass estimates, as often calculated for exploratory fisheries without integrated stock assessments. We also recommend that additional functions associated with mark-recapture analysis within CCAMLR’s fisheries be developed and made available to Members.