Bayesian assessments using models which allow for interchange on the breeding grounds of Southern Hemisphere humpback whale breeding Sub stocks C1 and C3

Johnston, Susan J; Butterworth, Doug S

Bayesian assessments using models which allow for interchange on the breeding grounds of Southern Hemisphere humpback whale breeding Sub stocks C1 and C3

Working Paper

2009

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

Bayesian stock assessment results for breeding sub-stocks C1 and C3 using models which allow for interchange on the breeding grounds as well as mixing on the feeding grounds are illustrated for four models – the sabbatical, tourist and migrant models and the resident model (for which interchange is set to zero.) Results are also presented for a range of sensitivity tests. The availability of photo-id data allows the estimation of interchange rates. The estimates of these interchange rates are generally low with posterior median estimates all below 6% p.a., and estimated trajectories are fairly similar for all models considered. With single exceptions, current (2006) posterior median population sizes relative to pre-exploitation levels are all estimated to exceed 80% for C1 and 90% for C3.