Occurrence and biological outlines of two speciesof Scylla (De Haan) in Chilika lagoon, India

The mud crab population in Chilika lagoon was hitherto considered as belonging to a single species of Scylla serrata. The present study, after examining colouration, reticulation on limbs, size range, minimum size at first maturity, habitat preference, fishery season, breeding and morphological traits, confirmed the co-existence of two species, Scylla tranquebarica (Fabricius,1798) and Scylla serrata (Forsskal,1755) in Chilika lagoon. The maximum size of Scylla tranquebarica (240mm / 2.8kg) and Scylla serrata (181mm / 0.83kg) recorded during the study were considered as the largest sizes so far recorded from Indian waters. Collection and estimation of landing statistics separately for two mud crab species from a single water body seemed to be the first attempt in the country. Scylla serrata and Scylla tranquebarica accounted for 81.52 and 18.48% share respectively in the average annual landing. Strategic conservation regulation need to be formulated for mud crab fishery in Chilika lagoon based on species-wise landings and biological information to prevent unregulated exploitation.