Evaluation of the Relevance of Some Environmental Factors to the Estimation of Migratory Timing and Yield for the Brown Shrimp of Pamlico Sound, North Carolina

Abstract

A linearized logistic model and a multiple linear model were used to relate environmental factors (week number, water temperature, salinity, air temperature, precipitation, net heating degree days, river discharge) to the time distribution of the cumulative proportion of catch and catch per unit effort of the brown shrimp (Penaeus aztecus), respectively. Multiple regression analysis yielded equations containing the week number, the water temperature, and an interaction term as the independent variables. Predictions of total annual yield and total annual catch per unit effort are made using the migratory time density approach. The time factor, represented by weeks numbered throughout the year, contributes the most in explaining the variation in the migratory timing. Models for predicting migratory behavior and yield in the brown shrimp should consider water temperature to be a significant factor. Although the models are not statistically precise, the empirical predictions are an improvement over existing estimators.