Biology of Meretrix casta (Chemnitz) and Paphia malabarica (Chemnitz) from Mulky estuary, Dakshina Kannada

Abstract

Meretrix casta and Paphia malabarica are the major species contributing to the clam fisheries of the Mulky estuary. Studies on age and growth indicated that M. casta attains 46.6 mm and P. malabarica 48.1 mm in one year The von Bertalanffy growth equation is fitted for both the species. most of these clams do not survive the second year. Length-weight relationship of both species and other dimensional relationships of M. casta are worked out. The major spawning season of M. casta and P. malabarica are Septtmbar-lVlarch and October-February rtspectlvely. In M. casta females are significantly dominant beyond 30 mm length. This species attains first maturity at a length of 17mmiHigh condition index in both the species coincided with peak spawning period. An analysis of rings on the shells of M. casta indicated that they are not useful in age determination. Various aspects of the biology of the above two species are discussed in relation to the ecological conditions of the Mulky estuary.