Population and Trophic Dynamics of Pacific hake (Merluccius productus)

Abstract

This paper explores the population and trophic dynamics of the coastal stock of Pacific hake (Merluccius productus). In particular, the biological mechanisms of growth, mortality (natural and fishing), migration, and bioenergetics are quantified in such a way that both fishery and trophic dynamics can be explored. The central focus of the analysis is an age-structured computer simulation model. Both uniform and seasonal relationships of weight on age are derived and provide markedly different estimates of trophic demands. Variable age-specific natural mortality yields cohort analysis estimates of stock biomass which correspond more closely to survey estimates than estimates based on constant natural mortality. Bioenergetic simulations indicate that both production of and consumption by hake may be considerably lower than for other similar gadoid species. The ratio of total annual production (growth and recruitment) to biomass is estimated to be 0.35 and the average annual daily consumption is estimated to be 0.4% BWD.