Reproductive aspects of Grapsus grapsus (Decapoda: Grapsidae) in islands of southeastern Gulf of California

Aspectos reproductivos de Grapsus grapsus (Decapoda: Grapsidae) en islas del sureste del Golfo de California

Objetive. The sex ratio, ovigerous females, first sexual maturity lengths and fecundity of Grapsus grapsus crab in the Lobos, Venados and Pajaros islands (southeastern Gulf of California) were analyzed. Materials and methods. Sampling was monthly between March 2011 and February 2012, collections were nocturnal at low tide, 30 crabs were collected in a quadrant (25 m²) for island and sampling. AN (mm) and PT (g) were determined. The proportion of sexes and size of first sexual maturity (AN_50%) was estimated, in ovigerous females, embryonic stages and fecundity (gravimetric method). Results. The sex ratio of M:H was 1:1.3. The average maturity was AN_50% 34.9 mm. It is evident the presence of ovigerous females (71.3%) and all the embryonic phases, 48% of ovigerous was red-orange phase. Eggs diameter from 1.1 to 5 µm, with an averange diameter of 2.05 µm. The mean fecundity was 24339.3 eggs. The maximum and minimum weight per female egg was 69.9 and 15.2 g. Conclusions. Based on the biological characteristics of the sex ratio, ovigerous females, first sexual maturity lengths and fecundity of G. grapsus, represent a favorable effect on its subsequent administration and management of this resource in this area.