Specific richness, size classes and growth parameters of the main fish species in the upper Mouhoun River basin in Burkina Faso

Abstract

In Burkina Faso, fisheries management based on compliance with the fishing gears being authorized by the legislations is inadequate. In this context, it is necessary to find other tools to assess the catch sizes of the species and the quality of the living environment of the fish. For this purpose, a sampling was carried out in three fishing sites in order to study the richness, the size class, the weight-length relationship of captured species and the condition factor of the dominant species during the rainy and dry seasons. The results showed that the three fishing sites were found to be species abundant ones with 43 species divided into 31 genera belonging to 18 families. The dominant species were: Oreochromis niloticus, Sarotherodon galilaeus, Heterotis niloticus, Auchenoglanis occidentalis and Synodontis schall. In Bama, the catch sizes of O. niloticus ranged from 7.5 to 25 cm while in Balla it varied from 12.5 to 32.5 cm. The size of S. galilaeus ranged from 7.5 to 22.5 cm, 12.5 to 30 cm and 15 to 25 cm in Bama, Balla and Samendeni, respectively. Values of the constant b of the weight-length relationship revealed that 50% of the species had negative allometric growth, 20% had isometric growth and 30% had positive allometric growth. This showed that some species are exploited below the size of their first maturity in some sites, which might compromise their long-term survival.