Fish Stock Assessment and Management Recommendations for the Oguta Lake Fishery, Imo State

This study conducted a stock assessment of the commercially exploited fish populations in Oguta Lake, Imo State, South East Nigeria, and developed management recommendations based on the findings. Oguta Lake is a natural oxbow lake supporting significant artisanal fisheries, yet it has received limited formal fisheries management attention. Catch sampling and length-frequency data were collected from artisanal landings at the two primary fishing communities on the lake over a six-month period. Major commercial species including Clarias gariepinus, Parachanna obscura, and Chrysichthys nigrodigitatus were assessed. Length-based stock assessment methods were applied using FiSAT II software to estimate growth, mortality, and exploitation parameters. Results indicated that all three target species were characterised by exploitation ratios exceeding 0.6, consistently above the sustainable reference point of 0.5. The estimated biomass of Clarias gariepinus was approximately 30 percent below the biomass at maximum sustainable yield. Recruitment patterns suggested year-round spawning with seasonal peaks coinciding with the early rainy season. Mesh size analysis of gill nets in use confirmed that undersized individuals were being harvested in substantial quantities. Current fishing effort was estimated to be 1.8 times the level associated with maximum sustainable yield. The study recommends the immediate implementation of a minimum mesh size regulation of 55 millimetres, introduction of a seasonal fishing closure of 60 days during peak recruitment, establishment of a community-based catch monitoring programme, and regular follow-up stock assessments every two years for Oguta Lake. Keywords: stock assessment, fisheries management, Oguta Lake, exploitation rate, artisanal fisheries