Genetic Diversity and Population Structure of Nile Tilapia (Oreochromis niloticus) in the Benue River Basin

Nile tilapia (Oreochromis niloticus) is the dominant commercially cultured fish species in Nigeria, with the Benue River basin in North Central Nigeria representing a major wild stock reservoir. Understanding the genetic structure of wild and farmed tilapia populations is essential for sustainable aquaculture development and fisheries conservation. This study assessed the genetic diversity and population structure of Nile tilapia from wild catches and adjacent aquaculture ponds in the Benue River basin using mitochondrial control region sequencing and microsatellite genotyping. A total of 180 fish were sampled from four sites. Twelve microsatellite loci were amplified and genotyped. Population structure was assessed using AMOVA, FST, and Bayesian clustering (STRUCTURE software). Mitochondrial haplotype network analysis was performed using TCS. Results indicated moderate genetic differentiation between wild and farmed populations, with evidence of genetic introgression in sites close to aquaculture facilities. Wild populations maintained higher allelic richness compared to farmed stocks. These findings recommend containment measures for farmed tilapia and inform selective breeding decisions for tilapia aquaculture programmes in the Benue River basin. Keywords: Nile tilapia, genetic diversity, microsatellites, Benue River basin, aquaculture genetics