The Texas shrimp fishery: analysis of six management alternatives using the general bioeconomic fishery stimulation model (GBFSM).

The shrimp fishery of Texas has been the focus of continuing resource management efforts. Six management alternatives, recently proposed in fishery management plans or legislation, are analyzed. Management alternatives consist of closure of specified areas for particular periods of time, changes in count size regulations, or both. The analyses were conducted using a computer simulation model General Bioeconomic Fishery Simulation Model designed to represent the important biological and economic processes of the Texas shrimp fishery. For given levels of growth coefficients and natural mortality coefficients the model produced results very close to historical landings in terms of volume, size and seasonal distribution. Six management alternatives were evaluated in terms of their impact on total landings, amount of discards, cost and returns, and fishing effort employed. Impacts were estimated both for the first year and for a long-run situation, which gave the industry time to adjust by increasing or decreasing the number of bay boats and Gulf vessels. Management alternatives closing Texas offshore waters in the Fisheries Conservation Zones simultaneously with state closure had a slightly negative impact on total landings in the first year. It was estimated that increased landings later in the year could not offset landings lost due to closure. The most significant increase in landings resulted from management alternatives including elimination of the count size law. This was reflected in both first-year and long-run equilibria. Under all management alternatives examined, the number of Gulf vessels increased and the number of bayboats declined. Management alternatives eliminating the size restriction on landed shrimp would have the greatest impact on increasing vessel numbers. Because the industry in 1980 is not in equilibrium, short-run increases in vessel profits associated with these management alternatives would reduce some of the pressure forcing vessels out of the industry. It was found that closure of inshore waters during the spring season would have a negative impact on total landings the first year and only a small positive impact at equilibrium. At equilibrium, Gulf vessel landings were estimated to increase by 2.65 million pounds (heads-off) annually, with bay landings being reduced by 2.50 million pounds.