Exploring the morphological dynamics of Nile tilapia (Oreochromis niloticus Linn. 1758) in Victoria Nile as depicted from geometric morphometrics

Abstract Background: Various anthropogenic activities continue to threaten the fish biodiversity of the East African water bodies such as the Victoria Nile. Although the Victoria Nile is a significant source of livelihood to human populations, the biology and ecology of Nile tilapia in this ecosystem remain understudied with little or no information on the morphology of the fish given varying and immense anthropogenic activities. Here, we use geometric morphometrics to examine the morphology/shape variations of Nile tilapia populations in Victoria Nile to gain insights into their current ecological state. Results: Our results indicate unexpected smaller body weights of Nile tilapia in Victoria Nile than in L. Victoria. Despite this, all the populations displayed condition factors of greater than 2 suggesting a healthy stock. We also report that the Upper and Lower Victoria Nile populations display morphological similarities. We note that Nile tilapia from Nalubale Dam Reservoir is morphologically distinct from the close neighboring Victoria Nile populations which are likely allied to the influence of the Nalubale Hydroelectric power dam as a barrier. Conclusion: Nile tilapia’s morphological variation appears to be influenced by various anthropogenic disturbances notably, overfishing, hydroelectric power dams, and fish translocational history in Uganda. Management should enforce regulatory frameworks to avert human-mediated activities as these are likely to compromise the sustainability of the fisheries. Further studies are required to follow these populations with molecular data to gain a deeper understanding of the fish species for sustainable management and conservation.