Seasonal Distribution of Penaeid Shrimps in the Estuary of the Imo River, Imo State

Penaeid shrimps are commercially important crustaceans that sustain artisanal fisheries in Nigerian coastal zones, yet their seasonal population dynamics in estuarine systems remain poorly documented. This study examined the seasonal distribution, species composition, and size structure of penaeid shrimps in the Imo River estuary, Imo State, South East Nigeria. Sampling was carried out monthly for six months using push nets and shore seines at four estuarine stations. Shrimps were identified, measured, and weighed following standard protocols. Catch per unit effort was computed for each species per station per month. Environmental variables including salinity, water temperature, turbidity, and dissolved oxygen were recorded simultaneously. Four penaeid species were identified: Penaeus notialis, Penaeus monodon, Metapenaeus monoceros, and Parapenaeopsis atlantica. Penaeus notialis was the most abundant species, comprising 58 percent of total catch. Abundance peaked during the wet season transition months of April and May, coinciding with reduced salinity and increased turbidity due to freshwater influx. Juveniles dominated catches during wet season months, while mature adults were more prevalent in dry season samples, suggesting an inshore spawning migration pattern. Catch per unit effort declined progressively from upstream to downstream stations. The study provides important biological data to inform the setting of minimum landing sizes and seasonal harvest restrictions for shrimp fisheries management in Imo estuarine zones. Keywords: Penaeidae, seasonal distribution, Imo River estuary, catch per unit effort, artisanal fisheries.