Population dynamics of the Asian green mussel <i>Perna viridis</i> (L.) from St. Mary’s islands off Malpe, India

Abstract

Size range of mussels in the population varies from 6.1 to 133.2 mm. Von Bertalanffy growth equation for length was <i>L_t</i> = 136.9 [1-<i>e ^{-0.42 ( t+0.38)}</i>]. Growth performance index (<i>Φ'</i>) was estimated as 3.896. Total mortality (<i>Z</i>) of the regime was 1.18 year⁻¹. Natural mortality (<i>M</i>) and fishing mortality (<i>F</i>) rates were 0.42 year⁻¹ and 0.76 year⁻¹ respectively. Total mortality based on mean size in the sample for the whole population ranged from 0.5380 (October 2005) to 2.2492 (December 2004). Cohort size was reduced by 50% within 6 months after settlement. Maximum and minimum densities of mussels were 5,404 no.m^-2 (December 2004) and 1,744 no.m^-2 (October 2005) respectively and the average was 3,105 no.m^-2. Biomass (total weight) of mussels varied from 8,910 g.m^-2 (November 2004) to 37,745 g.m^-2 (December 2005) at the study site during the study period. Average biomass was 22,754 g m^-2. Biomass values (total weight, wet weight, dry weight and shell weight) increased with the increasing growth of mussels. Specific production (<i>C</i>) ranged from 0.0488 (June 2005) to 0.1318 (January 2005). High specific production was recorded during post-monsoon season and low values during pre-monsoon season. Maximum length recorded (<i>L_max</i>) was 133.2 mm.