Variation in growth for Hecate Strait English sole (Parophrys vetulus) with implications for stock assessment

In this study we analysed length-at-age data to characterise the growth of English sole (Parophrys vetulus) and to examine the implications of incorporating uncertainty about growth into English sole stock assessment. Unlike previous analyses of English sole that employed Von Bertalanffy growth, we used a flexible parameterisation of growth after Schnute (1981) that better accommodated observed patterns in the length-at-age data. The model parameters always exist, even when the most appropriate growth form does not include a maximum size asymptote, and they have statistically stable properties. Also, the model parameters are expressed as quantities that have direct biological interpretation. Based on examination of annual growth parameter estimates, we concluded that a change in ageing methodology, sample bias and low sample size precluded analysis of the response of growth to environment and density-dependent effects. We also discuss the implications of uncertainty in the growth parameters on a yield per recruit analysis.