Population dynamics of the freshwater clam Galatea paradoxa (Donacidae) in the Cross River, Nigeria

Abstract

The growth of freshwater clam Galatea paradoxa (Born) from the Cross River, Nigeria, was studied based on a count of growth checks on shells, presumed to be laid down annually. Mean lengths at ages 1 to 5 were 4.1 cm, 5.9 cm, 7.4 cm, 8.4 cm and 9.0 cm, respectively; maximum observed size was 11.1 cm. Growth conformed to the von Bertallanffy growth model with the parameters L sub( infinity ) = 11.2 cm, K = 0.3 year super(-1) and t sub(0)=0.5 year super(-1). Total and natural mortalities were estimated at 0.8 and 0.3 year super(-1), respectively; the statusof the fishery is briefly discussed.