A Numerical Simulation Model of the Population Dynamics of Walleye Pollock, Theragra chalcogramma (Pallas 1811), in a Simplified Ecosystem : Part I, Model Description

This report is a description of an age-structured energetics and population model of walleye pollock, Theragra chalcogramma (Pallas 1811), in a simplified Bering Sea ecosystem consisting of phytoplankton, copepods, and euphausiids. The objective of the model is to study the theoretical effects of linkages among energy flow, recruitment, mortality (particularly due to cannibalism), and fecundity on the population dynamics and potential fishery yields of walleye pollock. The model pollock populations are driven by primary production in the form of phytoplankton. The model is principally defined using ordinary differential equations in an age-structured array approximating the integro- differential equation formulation for population dynamics. Equations, parameter values and initial conditions are given with their bibliographic sources. The model includes processes of diet selection, consumption rate, assimilation, respiration, starvation mortality, predatory mortality (due to cannibalism), reproduction, and fishing mortality. A subsequent report will describe the dynamics of the model pollock populations and other emergent properties. 1981 NMFS (National Marine Fisheries Service) NWFSC (Northwest Fisheries Science Center) AFSC (Alaska Fisheries Science Center) Library Public Domain 1864