Download FAR 2017/26 - Investigation of alternative model structures for the estimation of natural mortality in the Campbell Island Rise southern blue whiting (Micromesistius australis)

This study sought to identify assessment model structures for SBW 6I that estimate M. The current base case model produced strongly biased M estimates that were highly sensitive to a selection of M prior CV. Initial equilibrium age models produced stable estimates of M ranging from 0.18 and 0.19, depending on early catch history. Models minimising the influence of lognormal priors were also investigated. These investigations could not identify model structures for the unbiased estimates of M. It was recommended the assessment continues with 0.2 and sensitivities at 0.15 and 0.25.