Analysis of Climate-Driven Range Shifts in Marine Fish Species Along the Nigerian Continental Shelf Using Long-Term Trawl Survey Data

Ocean warming is driving poleward and depth-ward shifts in the distribution of marine fish species globally, with significant implications for ecosystem dynamics and fisheries management in tropical regions. This study analysed long-term trawl survey data from the Nigerian continental shelf to detect evidence of climate-driven distribution shifts in commercially important demersal fish species. Trawl survey datasets covering the period 1980 to 2023, compiled from the Nigerian Institute for Oceanography and Marine Research archives and published literature, were standardised and analysed. Depth and latitudinal centroid shifts for 24 demersal fish species were estimated using quantile regression on standardised abundance indices. Sea surface temperature and bottom temperature trends from HadSST4 and EN4 datasets were computed for the same period. Maximum entropy species distribution models were constructed under current and projected (2050 SSP2-4.5) temperature scenarios. Mean sea surface temperature in the study area increased by 0.29 degrees Celsius per decade over the analysis period. Significant deepening of distribution centroids was detected in 11 of 24 species, at a median rate of 1.8 metres per decade. Three demersal species showed significant southward latitudinal displacement of 0.4 to 0.9 degrees latitude per decade. Species distribution model projections indicated that 8 species face greater than 30 percent range reduction under 2050 temperature scenarios. Range contractions were concentrated in inshore shallower shelf areas currently used intensively by artisanal fishers. The study provides the first systematic climate distribution shift analysis for Nigerian continental shelf fish. Keywords: climate change, range shift, demersal fish, continental shelf, Nigeria.