A general framework for integrating the standardization of catch per unit of effort into stock assessment models

Abstract

A general framework is presented for integrating the standardization of catch per unit of effort (CPUE) into stock assessment models. Catchability is modeled using both continuous and categorical explanatory variables. The likelihood for the CPUE data is combined with the other likelihoods from the stock assessment model; the parameters used to model catchability are estimated simultaneously with the other parameters of the stock assessment model. The method is applied to a New Zealand rock lobster (Jasus edwardsii) stock, and the results are compared with those obtained using a generalized linear model. The point estimates are similar for both methods, but the confidence intervals from the integrated framework are much narrower. Simulation analysis supports the findings that the integrated approach gives narrower confidence intervals that more accurately represent the uncertainty in the parameter estimates, provided the model is correct.