Assessment of Fish Species Diversity in the Lower Niger River, Kogi State

This study assessed fish species diversity in the Lower Niger River within Kogi State, North Central Nigeria. Freshwater fisheries in this region support the livelihoods of thousands of artisanal fishing communities, yet systematic biodiversity records remain sparse. Samples were collected from five designated stations along a 40-kilometre stretch of the river using gill nets, cast nets, and traps over a six-month period. A total of 28 species across 14 families were recorded and identified using morphological keys. The Shannon-Wiener Diversity Index and Margalef Richness Index were applied to quantify species diversity and evenness. Results indicated moderate to high diversity at upstream stations, with diversity declining significantly near urban discharge points downstream. Cichlidae and Mormyridae were the most represented families, accounting for 42 percent of total catch. The study further documented the influence of seasonal variation and water physicochemical parameters, including pH, dissolved oxygen, and turbidity, on species occurrence and abundance. Human activities such as sand dredging, agricultural runoff, and subsistence overfishing were identified as primary threats to biodiversity. Recommendations include the establishment of no-take zones and regular monitoring programmes supported by state fisheries agencies. This research provides baseline data critical for sustainable fisheries management and conservation planning in the Lower Niger Basin. Keywords: fish diversity, Niger River, artisanal fishing, species richness, Kogi State