Density, biomass, growth, age, mortality and exploitation of wedge clam, <em>Donax incarnatus</em> (Gmelin) from Karnataka coast, India

Abstract

The size-frequency distribution method was used to study the rate of growth of Wedge clams of the genus <em>Donax </em>(Family: Donacidae). It was found that the clam grew up to 18.1, 24.0 and 26.2 mm at the 6^th, 12^th and 15^th months respectively. The life span of this was less than 2 years. Recruitment pattern was continuous with one major peak in February and March. The minimum and maximum densities of clams were 22 (July) and 1885 ind.m^-2 (December) respectively. Minimum and maximum values were 1.142 (July) and 193.612 (November) g.m^-2 respectively. Values of von Bertalanffy growth parameters (<em>L</em><em>_∝</em> = 28.35, <em>K </em>= 1.70, <em>t_o</em> = - 0.099) were estimated. The von Bertalanffy growth equation was <em>L_t</em> = 28.35 [1-<em>e</em> ^{-1.7(<em>t</em>+0.099)}]. Total mortality (<em>Z</em>), natural mortality (<em>M</em>) and fishing mortality (<em>F</em>) rates were 5.18 yr^-1, 2.61 yr^-1and 2.57 yr^-1 respectively. Exploitation level (<em>E</em>) of <em>D. incarnatus</em> was estimated at 0.50.