Dynamics of a Penaeid shrimp population and management implications.
In assessing present utilization of a stock of pink shrimp (Penaeidae) that supports an important commercial fishery in the eastern Gulf of Mexico, the interacton of population growth and mortality is critically analyzed. Estimates of the parameters involved were secured through a mark-recapture experiment wherein a biological stain served as the marking agent. The experiment was oriented in space and time so that exploitation of the marked population, which initially consisted of individuals uniform in size, provided measures of growth and mortality in the parent group during and immediately following its transition from prerecruit to postrecruit status. Throughout the experiment, the entire stock as well as the marked population were heavily fished. Upon examining the question of whether or not the fishery's production could be improved by postponing the start of fishing until the shrimp reach a size greater than the 70 headless-count designation now generally viewed as a practicable miniumum, it was noted that expediate growth, although relatively high, would be insufficient to offset substantial losses due to expected natural mortality. Even with a moderated increase in growth rate, and appreciably reduced natural mortality would have to be indicated before such a move could be considered feasible. Maximum potential yield in both weight and value is obtained with the minimum acceptable size that the fishery currently imposed.