Empirical Modelling of Climate-Driven Changes in Fish Habitat Suitability in the Chad Basin, Yobe State

Projecting changes in fish habitat suitability in response to climate-driven lake level and temperature changes is essential for forward-looking fisheries management in the Chad Basin, yet species distribution modelling for this system calibrated to recent climate data has not been conducted for the Yobe State sector. This study empirically models current and projected habitat suitability for four commercially important fish species, Lates niloticus, Alestes baremoze, Synodontis schall, and Oreochromis niloticus, in the Yobe sector of Lake Chad under two climate scenarios corresponding to moderate (RCP 4.5) and high (RCP 8.5) greenhouse gas emission pathways. Species occurrence records collected over three years of artisanal landing monitoring were combined with remotely sensed habitat variables including water surface temperature, water depth, turbidity, and aquatic vegetation cover derived from Landsat 8 and Sentinel-2 imagery. MaxEnt species distribution models were calibrated using occurrence records and projected onto 2035 and 2050 habitat variable scenarios derived from CORDEX-Africa regional climate model outputs. Results showed that habitat suitability for Lates niloticus declined by 34% and 61% under RCP 4.5 and RCP 8.5 by 2050, respectively, driven primarily by declining water depth and increasing temperature. Oreochromis niloticus showed greater resilience, with only a 14% suitability decline under RCP 4.5. The study provides spatially explicit habitat suitability projections for Yobe State fisheries managers and recommends climate-adaptive species management strategies prioritising habitat protection for thermally sensitive species.

Keywords: habitat suitability modelling, MaxEnt, climate change, Chad Basin, Yobe State