Estructura de tallas y relaciones biométricas del cangrejo roca Grapsus grapsus en las islas Lobos, Venados y Pájaros, Sinaloa, México

Abstract

Background. Artisan fishermen along the southern Sinaloa coast catch alternative species, for example the Grapsus grapsus rock crab without biological and fishing controls, when their catches are reduced or when the season for catching certain fish has ended. Goals. We analyzed the size structure and biometric relationships of G. grapsus on Lobos, Venados, and Pajaros Islands of Mazatlan Bay, Sinaloa, Mexico. Methods. The cephalothorax width (CW) and weight (W) were analyzed during a one-year period (March 2012-February 2013). Results. 926 organisms were collected (519 males y 407 females). Pajaros Island had the greater percentage (37.4%) of collected organisms, followed by Lobos (34.2%), and Venados (28.4%) Islands. The greatest values were CW=74.5 mm recorded at Pajaros Island and W = 138.2 g at Venados Island and the lowest values were CW=13.9 mm at Pajaros Island and BW =1.1 g at Lobos Island. Means of CW and W were 41.4 mm and 31.5 g, respectively. The means of CW and W were statistically different between the islands (CL, p = 0.009; W, p < 0.015). Conclusions. High determination coefficients between the variables were obtained, indicating isometric growth. Specimens of G. grapsus increase their size quickly and their weight very slowly.