Evaluation of the state of the shrimp fishery in the Gulf of Tehuantepec

Abstract

Considering the integration of the total catches of white, brown, blue and crystal shrimp in a single population, the shrimp fishery in the Gulf of Tehuantepec was evaluated between 1960 and 2002 . Schaefers model estimated a value of optimal effort (fOPT) of 151 ships and an optimal catch (COPT) of 2,342 ton (r = 0.723, p < 0.05). The models of Fox and Schaefer estimated 84 ships and 2,673 ton (r = 0.806 , p < 0.05), and 110 ships and 1,504 ton (I=39.41%), respectively. Considering the Schaefers model, two exploitation periods were observed. The first period from 1960 to 1980, during which the fishing effort was mantained relatively constant in approximately 150 and 200 ships; whereas, the second one, from 1981 to 2002, showed a fluctuation between 220 and 350 ships. Comparisons with other units of fishing effort were not made, nevertheless, the interannual variability of the capture in the first period was similar to that reported for the Gulf of Tehuantepec from 1949 to 1981, which considered the number of ships in order to develop the Schaefers model. Independently of the unit of the fishing effort utilized, both evaluations suggest that the optimal level of catch was reached and surpassed at the end of the 70s and the beginning of the 80s. This provoked the reduction of the catches during the second period. In this last period, the rate of artisanal exploitation between 1983 and 2000 was not estimated, nevertheless, we considered that it must have been greater than what was obtained by the marine fishery (0,69 annual). The combination of both fisheries has increased the level of fishing effort on the populations of shrimp in the Gulf of Tehuantepec, resulting in a critical level of explotation