Abstract:
Population ecology of the spiny rocky crabs, Thalamita crenata (Latrell, 1859) was conducted on Kung Krabaen Bay, Chanthaburi province from November 2010 to September 2011. 148 males and 159 females were found in 6 stations. Ratio of male to female were 1:1.07, the relationship between carapace width (CW) and weight (W) of male crab was W = 20.143CW0.7111 and female crab was W = 19.217 CW0.6277. The first sexual maturity of female was 1.37 cm. Spawning season had two peaks, the 1st peak was from March to June and the 2nd peak from November to December. In each season, the population density and distribution of crabs were found to be significantly different (p<0.05). The result also showed that high density of crab was found in rainy season over than dry season, especially in the rocky beach. The main food of crab was fish, shrimp and shell. Organic matter, sand, algae were found in a few. There were not found different significantly between the frequency of food in male and female crabs (p > 0.05). In contrat, there were significantly difference in the frequency of food in dry season and rainy season (p <0.05). The relationship between distribution of crabs and ecological factors was significantly with pH and the relationship between female crabs and ecological factors was correlated with salinity. The sustainablility management of this crab was proposed indeed; 1) increasing mesh size of collapsible crab trap and crab gill net, prohibiting catch the ovigerous female and juvenile crab lesser than 4 cm 2) supporting soft shell crab farming from spiny rocky crabs to reduce overharvest of blue swimming crab and mud crab in natural habitat. Species diversity of marine crabs at Kung Krabaen Bay. was also studied The result showed that there were 14 families, 31 generas and 48 species of marine crab at Kung Krabaen Bay.