Assessment of the Effects of Seasonal Variation on Fish Catch and Composition in Oguta Lake, Imo State

Understanding seasonal dynamics in fish catch composition and abundance is essential for developing effective management calendars for inland fisheries. This study assesses the effects of seasonal variation on fish catch, species composition, and size structure in Oguta Lake, Imo State, South East Nigeria, over a full annual cycle. Catch data were collected weekly from four active landing sites around the lake, monitoring species composition, individual fish weights and lengths, gear types used, and fishing effort in boat-hours. A total of 26 fish species were recorded across both seasons. Total catch per unit effort was significantly higher in the dry season, when reduced water volume concentrates fish populations and makes gear deployment more effective. Mean individual fish size was larger during the wet season catch, attributed to the influx of older, larger-bodied fish from flooded habitats. Juveniles dominated catches during the late dry season and early wet season transition, indicative of active recruitment periods. Market-sized fish accounted for 61% of dry season catches compared to 48% during the wet season. The study reveals distinct seasonal patterns in the Oguta Lake fishery that have direct implications for fishing effort regulation and closed season design, and recommends the introduction of a bi-annual closed season covering peak juvenile recruitment periods to safeguard the long-term productivity of this commercially important water body.

Keywords: seasonal variation, fish catch, Oguta Lake, inland fishery, species composition