Population genetics structure of wild and domesticated African catfish (Clarias gariepinus) in Victoria and Albertine Drainage Basins

Wildlife capture fisheries have declined tremendously due to overfishing resulting from high demand. Aquaculture is a viable option to meet this demand. The African catfish (Clarias gariepinus) is one of the major species cultured in several fish farms in Uganda. However, this catfish domestication has been done without knowledge on the genetic characteristics of this fish. Indeed profiling the genetic integrity of C. gariepinus populations on farms and in the wild would enable the establishment of potential source of broodstock within Albertine and Victoria drainage basins for optimum performance. In this study, genetic diversity, differentiation and demographic history and evolutionary relationships of wild and domesticated C. gariepinus were determined. Caudal fins from 180 catfish individuals were collected from four fish farms, Victoria wild (lakes Wamala and Victoria and River Rwizi) and Albertine wild (lakes Albert, Edward and George). They were sequenced for partial mitochondrial DNA control region. The mtDNA control region revealed 45 haplotypes in 68 polymorphic sites, two distinct groupings (i.e., Albertine and Victoria groups) and a relatively high overall genetic diversity. Apart from Kabeihura fish farm (h =0.222), a generally high genetic diversity was observed among Albertine wild (L. George (h=0.935), L. Edward (h=0.958) and L. Albert (h=1.000)), Victoria wild (L. Wamala (h=0.742) and R. Rwizi (h=0.600)) fish farms (POCIFF (h=0.897), KFF (h=0.800) and SIFFA (h=0.756)) C. gariepinus strains. No significant genetic differentiation was observed between Victoria wild and Albertine wild indicative of events of the late Pleistocene. Similarly, no significant genetic differentiation between Victoria wild and fish farm strains showing that all broodstock for farms included in this study were most likely obtained from Lake Victoria. The results from this study indicate that most domesticated fish are not genetically depauperate and further reveal that fish farmers pick brood stock from other farms and the wild irrespective of the locality basin. Our results provide a guideline and basis for genetic considerations while sourcing and locating broodstock in aquaculture enterprises for improving fish production.