GROWTH, PRODUCTIVITY, AND SIGNIFICANCE FOR FISHERY OF THE BIVALVE EGERIA-RADIATA (DONACIDAE) IN THE CROSS RIVER, NIGERIA

The population dynamics of the clam Egeria radiata inhabiting the Cros s River, Nigeria were investigated. From tagging-recapture data, a Von Bertalanffy growth function with L(infinity) = 98.9 mm and K = 0.828 y-1 was established. Total mortality Z was calculated to be 2.03 y-1. Natural mortality M and fishery mortality F were estimated to be 1.10 y-1 and 0.93 y-1, respectively, corresponding to an exploitation rate of 0.45. Total annual yield by artisanal fishermen was estimated to be 600 tons wet mass.