Ichthyofauna Diversity and Abundance of Obafemi Awolowo University (Opa) Reservoir

Abstract

Between August 2015 and July 2016, fresh adult fish samples were collected monthly using traps and gill nets to investigate the ichthyofauna diversity and abundance of fish communities in Opa reservoir. The research was to provide baseline information on fish species richness, abundance, and condition factors of the fish species in Opa reservoir since different inland waterbodies have diverse species. The fishes were identified, and morphometric measurements were recorded. A total of 387 fish samples were analyzed, comprising seven families of twelve species. The Cichlidae family dominated the reservoir with six fish species throughout the sampling period. The results revealed that more fish species were caught in the rainy season than the dry season. However, the biological index of the fish community, such as the Shannon and Simpson diversity index, showed higher diversity value in the dry season as against the rainy season. The condition factor revealed that Hemichromis fasciatus had the highest mean value, indicating that the fish had signs of good well-being and nutritional sufficiency while Mormyrus rume recorded the lowest mean value which suggests that the fish had limited amount of food resources. The abundance of Coptodon zillii and Sarotherodon galilaeus was significant (p < 0.05) compared to other fish species populations. The study observed that the diversity and abundance of the fish species in Opa reservoir compared favorably with other water bodies. The sex ratio of the fish species recorded showed a slight variation in the expected ratio 1:1 of male to female. However, it revealed steady population growth in a favourable environment as indicated by the condition factor of the fishes