A Stochastic Age-Structured Population Model of Striped Bass (Morone saxatilis) in the Potomac River

Abstract

Deterministic age-structured models of fish populations apparently neglect stochastic fluctuations in the catch per unit effort of yearlings and of adult fish. A model is described of an age-structured population in which the survival of eggs to yearlings fluctuates randomly, but all other age-specific rates of survival and of egg-laying are constant. For such a stochastic model, 2 measures of the long-term population growth rate are the average growth rate of the population size and the growth rate of the average population size. Both measures are computed analytically for a simplified model representing only eggs and reproductive adults. For a model of the striped bass (M. saxatilis) population spawning in the Potomac River, both point and interval estimates of the growth rate of the average population size are computed. Some statistical tests of the correctness of this stochastic model are illustrated.