A study of Texas shrimp populations, 1974

Brown shrimp (Penaeus aztecus) were monitored in five coastal bays during spring to predict the time of their bay-to-Gulf migration. The Texas Parks and Wildlife Commission used the predicted late May or early June onset of migration to set 1 June as the starting date of the 45-day closed season in the shallow Gulf, ie., from the coast out to 18.53 km (10 nautical miles). The prediction was correct, and the closed season allowed a portion of the brown shrimp population to reach a large size before harvest. Although the abundance of juvenile brown shrimp in the bays indicated that stocks were adequate, brown shrimp landings of 16.1 million kg (35.5 million lb) heads-off were poor. This may have been the result of inflated operational costs that caused many shrimpers to remain in port. White shrimp (P. setiferus) were sampled to determine if bays open to commercial shrimping contained an abundance of undersize shrimp (over 65 headless to a pound) during the fall bay season (15 August- 15 December). Sample analyses showed that 31.9% of white shrimp were of legal size in Galveston Bay, 24.6% in Matagorda Bay and 33.9% in Aransas Bay. Few white shrimp were of legal size in secondary bays of the Galveston (5.2%) and Matagorda (1.7%) Bay systems. Analysis of commercial catch data indicated that the brown shrimp catch per 24 h of fishing time off Galveston has decreased since 1968 while total catch, although irregular, did not show this trend. Analysis of white shrimp catch data from the same area suggested an increase in catch per-unit-effort and catch since 1967. The decline in the shrimp catch in Sabine Lake was accompanied by a decrease in catch per-unit-effort. This decline was attributed to large freshwater discharges into the lake and alteration of nursery habitat. Shrimp catches from the Gulf off Sabine and Calcasieu Lakes have not declined due to an increase in fishing effort.