Capture-recapture analyses of humpback whale population sizes and increase rates: breeding sub-stock B1

Abstract

Maximum likelihood and Bayesian approaches are applied to estimate parameters of a simple experimental growth model for the humpback whales of breeding sub-stock B1 from photo-ID and genotypic capture-recapture data for all observation sites combined and for Iguela only. The maximum likelihood estimates are generally rather imprecise, and some estimates for the annual growth rate r are demographically unrealistic. Bayesian results, for which a prior restricts its r to a demographically plausible range of [0; 0.106], are more reliable and suggest a population of size 7600 [95% PI: 6600-8800] in 2003, with r at 8.5% [95% PI: 3.7%-10.4%]. These results, are however, intended primarily as illustrative of the methodologies, and to facilitate further discussion and model refinement. This will need, inter alia, to consider the appropriateness of aggregating data from different sites.