Breeding Cycle of Thalamita crenata (Latreille, 1829) at Gazi Creek (Maftaha Bay), Kenya

Abstract

Thalamita crenata (Latreille, 1829) is a crustacean decapod that occurs in inter- and sub-tidal environments in the main water channels of the eastern Africa coast. The sandy pools at Gazi creek are areas for artisanal crab fishery. For this study, crabs were collected during low tide from April 1990–March 1991, sexed and measured (carapace width). Females were examined for ovary maturity which was recorded in four classes. It was found that there was no significant difference in male to female ratio between months (c2 = 16.83; d.f.= 11; P > 0.05), but the overall sex ratio was significantly different from 1:1 (c2 = 19.577; d.f.= 1; P < 0.05). Size heterogeneity between sexes was also significantly different (c2 = 112.2; d.f. = 12; P < 0.05). The existence of continuous breeding was inferred from the percentage of ovigerous female crabs. In addition, the relative abundance of ovigerous female crabs in relation to carapace width, percentage frequency of maturity stages of all mature female crabs as well as the mean monthly carapace width of all female crabs obtained during the study period was also taken into account.