Assessment of fish distribution, composition and abundance in Otamiri River, Imo State, Nigeria

Study on the fish distribution, composition and abundance in Otamiri River was carried out between January and December, 2021. Three sampling points (Stations 1, 2 & 3) were selected along the stretch of the river and used for the study. Fish population was assessed using different fishing gears such as hooks and lines, gillnets, cast nets and traps while one-man dugout and planked canoes were the crafts used. Species diversity indices were estimated using standard procedure. Results revealed a total of 757 fish samples comprising of 15 species, 10 genera, 9 families and 4 orders. The family Cichlidae ranked the highest as the most abundant fish species having 363 samples, while Distichodontidae ranked the lowest with just 5 fish specimen. The highest species richness (15) was recorded between the months of January and March while the least value (11) was obtained between April and June. Simpson`s Index (D) value ranged from 0.02 between July and September and 0.005 between the months of January and March. Results of Simpson`s Reciprocal Index (1/D) showed that fish species caught between May and August were not as diverse as those obtained between September and December. This may indicate that some anthropogenic activities (agricultural/crop farms, construction sites, sewage discharges, timber harvesting, industrial discharge, mining and sand dredging) observed at the study sites tended to increase during raining season which subsequently led to the decrease in fish diversity. These activities could be said to have some deleterious effects on fish distribution, composition and abundance in Otamiri River. Thus management strategies should be put in place by relevant authorities to check human activities in the area.