Estimación de parámetros biológico-pesqueros para el pargo mancha Lutjanus guttatus en el Golfo de Nicoya, Costa Rica. (ING)

Abstract

The spotted snapper Lutjanus guttatus is one of the most important demersal species of the Pacific Coast of Costa Rica. This demersal fish is caught mainly by the artesanal fleet with gill nets and bottom long lines in the external zone of the Nicoya Gulf, producing around 62 tonnes in 1996. Nevertheless not much attention have been paid to the study of this species. According to national statics the tendency in recent years for the spotted snapper is to decrease in landings as well as in size of capture. This could be a sign of overexploitation of this species which lead us to the development of the present study. The degree of exploitation exerted on this population was quantified through the estimation of the instantaneous rate of total, natural and fishing mortality: 1.2, 0.6 and 0.6/year, respectively. This means that this population is completely exploited and that no further fishing effort should be applied to this stock. As part of this study the sex ratio was estimated, which did not depart significantly from 1:1. The total length vs. total weight relationship was also estimated and no sex related differences were found, which supports the idea that this species presents no sexual dimorphism. Length at first maturity for the population was 33 ± 3 cm total length. The Von Bertalanffy growth parameters, L∞ and k, 67 cm and 0.30/years respectively, show that the spotted snapper is a slow growing species with a longevity of around 10 years.