Análisis de la pesca del mero Epinephelus morio
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The red grouper fishery is in its decline phase presenting an average annual catch of 8191 t during the 1999 to 2003 period. Through these years Cuban fleet has reduced its fishing area toward the oriental region of the Campeche Bank while the artisanal fleet extended, increasing the overlap of sizes catched by the arisanal-industrial and artisanal-cuban fleets. The size composition of the catch shows that most of the fishes are captured before first maturation size. First catch age is 2 years, and complete fishery recruitment is at age 3 (age of first maturation), this being a factor against fishing sustainability and forcing adoption of management strategies. The natural mortality is calculated (M) for the each age in the fishery by the function Y = 2.73634 e - 0.31985 X, to avoid estimation biases and to show the differences in mortality between the red grouper development stages. The analysis of catchability (q) showed changes in fishing strategies and an increment in his value. The fishing effort was standardized for the first time among the three fleets, and total Cpue estimated; this which shows a decrease of 32% during the analyzed period. The Fishing mortality (F) estimation was based on q values for each age and the standardized fishing effort, and shows an increasing trend during the period. The population total size decreased in 27% being located below the PRL. The biomass decrease was evident in the Cpue estimated from the commercial fleets and from the Research Cruises. The vulnerability of the available biomass is close to 1 (maximum value) for the industrial and Cuban fleet during the entire period, while for the artisanal its close to 1 only since 1997. Recruitment shows low values during the years 1986, 1990, 1992, and a sustained decreasing trend since 1996. The stock-recruitment relations was fitted to the dense-dependency model proposed by Ricker (1954) and generalized by Schnute (1985), where recruitment (R) decreases with population growth, because of food and habitat competition. Compensatory mortality regulates recruitment as a function of population abundance. The simulation considering catch quotas designed to reach the PRL and PRO showed biomass recovery up to PRL for the three scenarios, while the PRO is never reached within the simulated period (until 2022). The simulation considering exclusion of fleet showed that the artisanal and industrial fleets are those having strongest impact on the biomass. The change of first catch age from 2 to 3 increases the maximum Y/R, from 0.8 to 0.93 Kg/r. It can be noted that for a Tc = 3 years the maximum is reached with a reduction of 40% of the current F, underlying the need for a fishing effort reduction. Management strategies are proposed which includes establishment of minimum size (30cm Lt), no-fishing period during reproductive season (February to April), no-fishing areas to protect juvenile distribution (areas < 20m depth) and spawns (oriental region), and an increase in the fishhook size (huachinanguero < No.5). Further, it is proposed limiting fishing in areas of high fecundity females and large males (areas > 60 -70m depth). The number of MPAa should increase. The catch quota system is not recommended for the Mexican fleets because of the fishery characteristics. In the current context the comanagement should be included in the management plan for the red grouper.
- 2. Tesis (CIP)