Fish Population Structure and its Relation to Fisheries Yield in Small Reservoirs in Côte d'Ivoire

Abstract

Abstract Lack of reliable data on the fisheries of northern Cote d’Ivore reservoirs is a major limi-tation for management of the fish stocks. As individual reservoirs cannot be studied due tothe high costs and lack of trained investigators, empirical and production models have tobe used to evaluate exploitation rates and fisheries potential. Daily yield (DY, in kg fishingday 1 year ) and total catch (TC, in kgyear 1 ) appear to be better descriptors than annual yield (in kg ha 1 year ). TC is related to variables linked to nutrient availability(watershed area, conductivity and Morphoedaphic Index). DY is related to fish speciesrichness and to reservoir area, indicating that fish population structure could be a key tounderstanding the patterns observed. Correlation between fish population structure andyield was significant. It was hypothesised that overall catch, TC, is related to nutrient avail-ability, but that catch per unit effort is related to the presence of given species in the reser-voirs, and particularly to the presence of bottom feeding species.Keywords: fish population structure, fisheries, reservoirs, yield models.