Development and application of a bioenergetics model for juvenile walleye Pollock

Abstract

A bioenergetics model was parameterized for age‐0 walleye pollock, Theragra chalcogramma, based on a synthesis of literature data. The sensitivity of the new parameters was tested by individual parameter perturbation (IPP) analysis. The model was applied to estimate individual and total cohort food consumption of age‐0 pollock in two areas of high pollock density in the Gulf of Alaska during the summer of 1990. Total cohort consumption was compared with zooplankton biomass and production estimates for the same areas and times of the year. The model was also used to examine the bioenergetic implications of age‐0 pollock diel vertical migration through a thermal gradient. During a 1‐month bioenergetics simulation, individual daily consumption decreased from 16·0 to 6·0% of wet body weight. Daily ration estimates corresponded well with independent field estimates of daily ration for the same areas and time of the year. Comparison of total cohort consumption with prey availability (production and biomass) indicated minimal potential for food limitation. Bioenergetic optimization of growth can be a potential benefit of diel vertical migration to age‐0 pollock, however more information on prey density and distribution is needed to test this hypothesis thoroughly.