Management implications of recruitment seasonality in the Texas fishery for the brown shrimp, Penaeus aztecus : a simulation study

Abstract

The relationship between recruitment seasonality and ordination of alternative management policies for the Texas brown shrimp (Penaeus aztecus) fishery is explored through utilization of a general stochastic simulation model developed for annual crop marine fisheries. The model represents harvest dynamics within the fishery through a series of finite difference equations representing recruitment, growth, migration, and mortality of brown shrimp, and fishing effort. The model is parameterized to reflect two alternative representations of brown shrimp recruitment dynamics, and the behavior of each model version is explored under four management policy options. The alternative recruitment representations differ in temporal pattern of postlarval brown shrimp immigration into coastal estuaries, and the management policy options reflect variations in seasonal closures and minimum size restrictions for the fishery. Analysis of model outputs identified a statistically significant interaction between recruitment representation and the performance of the alternative management policies based upon predicted harvests within the fishery. This interaction indicates the failure of the alternative recruitment model versions to produce a consistent predicted harvest response over all management policy options. Under an average representation of postlarval recruitment pattern, no significant differences in management option performance were detected, while two of four management options produced significantly lower harvests under a seasonally variable recruitment pattern.