Reproductive biology of blue swimming crab (Portunus pelagicus Linnaeus, 1758) in Lasongko Bay, Southeast Sulawesi-Indonesia

Information about reproductive biology is significantly needed in management of blue swimming crab (Portunus pelagicus) fishery. This research informs spatial and temporal sex ratio, gonadal development, gonado somatic index (GSI) and first size sexual maturity of male and female crab, as well as crab spawning season in Lasongko Bay, Southeast Sulawesi. Crab collection were conducted with gillnet in five different types of habitat. Gonadal development of crab was examined by their color and morphological characters. Sex ratio was analyzed of χ 2 test, and gonadal development proportion of male and female crabs were described. Gonado somatic index (GSI) among stations were analyzed by one-way ANOVA and followed by Tukey's test. Sex ratio of crabs spatially and temporally of generally did not differ significantly from 1:1. Gonad developments of male and female crab were varied spatially and temporally. GSI at every gonad development stage of male and female crabs generally was not significantly different among stations. GSI of male crab was smaller than the female crab. The first sexual maturity size of male and female crabs were 109.8 mm carapace width (CW) and 115.7 mm CW, respectively. The crab spawned in Lasongko Bay the whole year, and three peaks of spawning season were detected.