Population dynamics of the edible clam Meretrix casta (Chemnitz) (International Union for Conservation of Nature status: Vulnerable) from two estuaries of North Kerala, south west coast of India

Abstract

The population parameters of the edible clam Meretrix casta (Chemnitz) from two estuaries along the coast of north Kerala, Southern India were estimated. M. casta has been cited as vulnerable as per al. (2006a). Growth of M. casta from the east coast has been reported by Abraham (1963), Durve (1970: 73) and Sreenivasan (1983). Jayawickrema and Wijeyratne (2009) have described the population dynamics of M. (IUCN) population status. The asymptotic length (L∞) for M. casta from Chaliyar estuary was 24.24 mm. The growth coefficient (K) was 1.8-1. The growth performance index (ф') was found to be 1.92 and t0 was calculated at -0.04283547 years. The length weight relationship is given by Log Y = -1.259635861 + 3.090977418Log X, r = 0.903010085. The total mortality (Z) estimate for M. casta from Chaliyar estuary was 3.92 year-1; fishing mortality (F) 2.12 year-1. Exploitation level (E) was 0.54. The asymptotic length (L∞) for M. casta from Kavvai estuary was 26.5 mm. The growth coefficient (K) was 2.0-1. The growth performance index (ф') was found to be 2.03 and t0 was calculated at -0.03441665 years. The length weight relationship is given by Log Y = -0.98701877 + 3.054878207 Log X, r = 0.613724895. The total mortality (Z) estimate for M. casta from Kavvai estuary was 2.98 year-1; fishing mortality (F) 0.98 year-1. Exploitation level (E) was 0.33. The M. casta is under exploited from both the estuaries. There is potential for increased exploitation of the edible clam from both estuaries since the present exploitation levels are far below the maximum sustainable yield (MSY).