Genetic structure of Nile tilapia (Oreochromis niloticus, L. 1758) in protected and unprotected freshwater lakes in East Africa

There has been a drastic decline in the size of cichlid fishes populations since the beginning of the 20 th century. This fish decline is mainly caused by an increase in the size of the human population, increased fishing pressure and fish introductions. This decline results in a reduction in genetic diversity in the surviving populations as a result of genetic drift. The Ecosystem Approach to Fisheries Management agitates for provision of Marine Protected Areas (MPAs) which seem to be effective in developed countries. However, efforts to control artisanal fisheries through protection have not been adequately assessed in East African Freshwater lakes. Assessment of genetic structure in populations is important for their future conservation and management. The population genetic structure of the Nile tilapia was assessed using nucleotide variation of mitochondrial control region sequences and four nuclear microsatellite loci in 128 individuals from seven localities. 43 mitochondrial DNA (mtDNA) haplotypes were observed, fourteen of which were geographically localized. The study revealed a significant genetic differentiation between the populations at the mitochondrial and microsatellite loci. The possible contributions from human activities such as water pollution, overfishing and fish introductions are also discussed. Keywords : Genetic structure, Nile tilapia, overfishing, freshwater protected areas DOI: 10.7176/JBAH/14-4-02 Publication date: December 30 th 2024