Reproductive biology of the freshwater crab, Travancoriana schirnerae Bott, 1969 (Brachyura: Gecarcinucidae)

Abstract

The reproductive biology of the freshwater crab Travancoriana schirnerae was studied with respect to the following traits: mating pattern, gonadosomatic index (GSI), vas deferens factor (VD factor), breeding period and fecundity, during the period from June 2009-October 2011. A total of 3605 individuals were collected, of which 2168 (60%) were males and 1437 (40%) females. The population was divided into juvenile males (15.3%), adult males (45%), juvenile females (9.3%), adult non-ovigerous females (27.9%), ovigerous females (0.6%) and juvenile carrying females (1.9%). Mating occurred between postmoult females and hard intermoult males and the mating period extended from June-October. The GSI peaked in March for females and decreased after spawning in April. For males, the maximum values for GSI and VD factor were recorded in July. The breeding season extended from February-May and the highest frequency of ovigerous females was observed in March. The mean fecundity was 222 ± 43. Juvenile carrying females appeared in the population from April-July, with the highest percentage in May. The mean egg diameter was 2.38 ± 0.33 mm. Average number of juveniles carried by females was 204 ± 40. Recruitment of juveniles to the population was recorded at the onset of rainy season in June.