Temporal Patterns of Artisanal Fishing Effort and CPUE in the Nigerian Waters of Lake Chad

This study analysed temporal patterns of artisanal fishing effort and catch per unit effort (CPUE) in the Nigerian section of Lake Chad over a decade spanning 2014 to 2024, to determine trends in stock status and fishing pressure. Lake Chad has experienced dramatic surface area reduction over recent decades, with major consequences for fish habitat and productivity, yet systematic analysis of fishing effort and CPUE trends remains sparse in the published literature. Primary data were collected from logbook records maintained by fisher cooperative groups in four fishing communities in Borno and Yobe states, supplemented by regular landings surveys and key informant interviews. Fishing effort was standardised as number of net-days per month, and CPUE was expressed as kilograms per net-day. Time series analysis including Mann-Kendall trend tests and seasonal decomposition were applied to monthly effort and CPUE data. Results demonstrated a significant declining trend in CPUE of 4.2 percent per year over the study period, with particularly steep declines from 2018 to 2021. Total fishing effort declined simultaneously, contradicting the classic effort-response model and suggesting that the CPUE decline reflected genuine stock reduction rather than overfishing alone. Seasonal patterns showed peak CPUE during the post-flooding recession period when fish aggregate in shrinking pools. Lates niloticus and Alestes spp. showed the most pronounced CPUE declines. The study recommends the establishment of a formal catch monitoring system for Lake Chad, international coordination through the Lake Chad Basin Commission, and urgent consideration of effort reduction measures alongside habitat management to reverse declining stock trends. Keywords: CPUE trends, fishing effort, Lake Chad, stock status, temporal analysis