FISH DIVERSITY ASSESSMENT IN A MANGROVE ECOSYSTEM OF SOUTH BENIN (WEST AFRICA).

Abstract

Fish is an important food for many rural populations particularly in Africa. In order to assess the current state of those resources of the Ouidah lagoon in south Benin, a study has been carried out. It aims at investigating on the water quality and to assess the fish diversity of Ouidah lagoon. In this study, water quality parameters such as temperature, pH, dissolved oxygen and depth were measured monthly. Common fishing gears were identified and fish landing from local fishermen were recorded monthly. The results of the water quality analysis show that there is a significant difference between the values of dissolved oxygen, pH and depth of the different stations unlike other physicochemical parameters. Twenty-one (21) fish species belonging to sixteen (16) families were identified. Cichlids were the most represented family (19.09%) with four species, followed by Clupeids (9.52%) with two species. Other fish families such as, Elopidae, Gerreidae, Haemilidae, Aralichthydae, are represented only by one specie. In Ouidah lagoon, local fishermen use different gears for fishing: gillnets, throwing nets and traps. Biological indexes calculated showed differences between fish diversity. It is noted also a bad distribution of individuals from one specie to another. Fish distribution in Ouidah lagoon has been influenced by sea through fish migrations and the rehabilitation of the mangrove swamp in the zone which provides better ecological conditions.