Modelling the Spatial Distribution of Artisanal Fishing Effort in Lake Chad Using Satellite Telemetry and GIS in Borno State

Quantifying the spatial distribution of fishing effort in Lake Chad is essential for identifying areas subject to overexploitation and for designing spatially targeted conservation measures, yet GPS-tracked fishing effort data for the Nigerian sector of this internationally managed water body are unavailable. This study models the spatial distribution of artisanal fishing effort in the Nigerian sector of Lake Chad using GPS data loggers deployed on 60 canoes operated by fishers in Baga and Kukawa districts of Borno State over a nine-month period. Effort data were integrated with fish catch weight records maintained by fishers in standardised logbooks. GIS kernel density estimation was applied to map fishing effort density, and hotspot analysis was conducted using Getis-Ord Gi statistics. Bayesian spatiotemporal models were fitted to identify predictors of effort distribution using lake depth, water transparency, aquatic vegetation cover, and distance from settlement as covariates. Results identified six primary effort hotspots concentrated in shallow, vegetated zones of 2 to 4 metres depth. Effort intensity was highest during the dry season, when fish concentrations were predictable in contracting water bodies. Catch per unit effort in high-effort hotspots was 38% lower than in low-effort areas, consistent with localised depletion. The study provides the first spatially explicit fishing effort model for the Nigerian sector of Lake Chad and recommends the use of the resulting maps as the spatial basis for designing no-take zones under the Lake Chad Basin Commission's joint fisheries management plan.

Keywords: fishing effort, spatial modelling, Lake Chad, satellite telemetry, Borno State