The Mangrove Fishes in the Benin Estuarine System (Benin,West Africa) : Diversity, Degradation And Management Implications
A preliminary study of the mangrove fishes was undertaken from March 2000 to September 2001 in the Benin estuarine lagoon system in connected to the Mono river; a dam was constructed on this river to provide the Togo and Benin countries with electricity. The research aims to investigate fish species diversity and ecosystem degradation impacts in order to protect and to improve the mangrove fish resources. Specific objectives were (1) to investigate fish assemblages and distribution in the mangrove/estuarine habitat; (2) to investigate relationships between environment features and biological attributes; (3) to evaluate the estuarine ecosystem degradation, with regard to mangrove destruction and recent evolution of the Mono river caused by a dam construction, and impacts on fish population (4) to survey socioeconomic aspects of resources exploitation and (5) to initiate a resource management / conservation plan in participatory approaches. Preliminary results from wet and dry season samplings in the four habitat categories, mangrove fringe, adjacent open water, adjacent marginal vegetation and channel are as follow: The two dominant species of mangroves, Rizophora racemosa and Avicennia africana, are being intensively degraded for domestic use such as firewood. The fish assemblages was dominated by the detritivores (39.4%) and planktinovores/microcarnivores (45.6%). Overall, 51 fish species belonging to 26 families were collected. Cichlidae (5 species), Eleotridae (7 species), Mugilidae (5 species) were the most speciose families. Six (6) species, Sarotherodon melanotheron (Cichlidae), Kribia nana (Eleotridae), Gerres melanopterus (Gerreidae), Hemichromis fasciatus (Cichlidae), Ethmalosa fimbriata (Clupeidae), Aplocheilichthys spilauch en (Cyprinotontidae), dominated the sample and account for about 80%. Sarotherodon melanotheron constituted the major dominant species and account numerically for about 29% of the total catches and 46.7% of the total biomass.
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