POPULATION-DYNAMICS OF VENUS-ANTIQUA (BIVALVIA, VENERACEA) IN THE BAHIA-DE-YALDAD, ISLA-DE-CHILOE, SOUTHERN CHILE

Venus antiqua is a dominant member of intertidal and shallow subtidal soft bottom communities in southern Chile, where it is a significant resource for artisanal fisheries. Growth, mortality and productivity of V. antiqua were investigated at an intertidal flat in Bahia de Yaldad, Chiloe. Based on growth increment data obtained from a 20 months tagging-recapture experiment, the parameters of the seasonally oscillating von Bertalanffy function were estimated to be L(infinity) = 80.0 mm, K = 0.183 y-1, C = 1.211 and t(s) = 0.995. Production of V. antiqua is distinctly higher than in other species of the superfamily Veneracea. Annual production amounted to 40.69 g AFDM . m-2-y-1 (somatic tissue), 26.42 g AFDM . m-2.y-1 (shell organic matter) and 2.00 g AFDM . m-2 y-1 (gonad), respectively, corresponding to a P/BBAR; ratio of 0.585 y-1. Total mortality Z, natural mortality M and fishing mortality F were estimated to be 0.664 y-1, 0.333 y-1 and 0.331 y-1, respectively. The high exploitation rate E, 0.498, indicates serious overexploitation of the stock despite the closure of the fishery.