A Quantitative Measure of Migratory Timing Applied to the Commercial Brown Shrimp Fishery in North Carolina

Abstract

A quantitative description of the migratory timing of the brown shrimp (Penaens aztecns) was estimated from monthly state-wide (1966-1978) and weekly area-specific (1978-1980) catch and effort data from Pamlico Sound, the Neuse River, and Core Sound, North Carolina. Descriptive statistics for timing are defined and calculated. Based on the average of weekly catch data, 25% of the migration occurs in July, 50% in August, and 25% during September-November in Pamlico Sound, the major harvest area. Analysis of migratory timing is an improved method of predicting total yield even during years of apparently aberrant environmental conditions. It is suggested that the impact of various physical factors on the progress of the fishery in time and space can be objectively evaluated by using descriptive statistics as dependent variables in modeling efforts.