Community structure of Mochokidae (Jordan, 1923) fishes from Niger River at Northern Benin: implications for conservation and sustainable exploitation

Abstract

In Niger River in Benin, Mochokid fishes constitute valuable fishery resources of high commercial and economic importance. An ichtyological survey targeted to Mochokidae family was conducted in Niger River to document the community structure of these taxa in order to contribute to species management and sustainable exploitation. Fish individuals were sampled every month from February 2015 to July 2016 from artisanal fisheries and experimental catches using gillnets, cast nets, seines and longlines. The results indicated that the Niger River in Benin was rich of fourteen (14) species belonging to one (1) genus, Synodontis. Numerically, three (3) species, Synodontis schall (74.50%), Synodontis membranaceus (16.79%) and Synodontis nigrita (2.24%) were the most abundant. Likewise, three (3) Mochokidae, Synodontis schall, Synodontis membranaceus and Synodontis clarias showed a wide distribution and consistently occurred in all sampling sites. Seasonaly, the flooding period was the most diverse season showing the highest Shannon-Weaver index of species diversity H’ =1.65. Though under many degradation factors, the water quality of the Niger River was globally favorable for primary production and for the survival and growth of fishes. Overall, cumulated Mochokidae abundances significantly (P<0.05) increased with dissolved oxygen concentration. The multitude threats depicted were overfishing, dumping of domestic wastes, invasion of floating plants, introduction of exotic fish species, and the use of chemicals fertilizers/pesticides for adjacent agriculture require a community-based approach of ecosystem management that should include habitat protection, species conservation and valorization in order to guaranty the sustainable exploitation of the Mochokidae fishes in the Niger River.