Towards Conservation of the Endangered Singida Tilapia ,Oreochromis esculentus (Graham 1929) of the L. Victoria Basin, Kenya

The Singida tilapia, Oreochromis esculentus (Graham, 1929), is an indigenous tilapiine cichlid of Lake Victoria that was once among the most valuable commercial and food fish species for communities around the lake. Since the 1960s, the species has experienced a drastic decline, disappearing from landings due to overfishing, the introduction of invasive predators such as Lates niloticus (Nile perch), competition for resources and hybridization with exotic Oreochromis species and environmental degradation. As a result, it is now considered critically endangered, persisting mainly in isolated refugia such as Lake Kanyaboli, as a remnant population. Genetic assessments in the 1990s, indicated that the L. Kanyaboli population was relatively pure, exhibiting distinct mitochondrial haplotypes consistent with long term isolation. By 2011, studies showed genetic introgression with the invasive O. niloticus, with only three haplotypes remaining private to the L. Kanyaboli population, whereas in the broader Yala Swamp ecosystem, eight haplotypes were identified, highlighting both shared ancestry and localized genetic differentiation. This is mainly due to aquaculture-related introductions and habitat degradation that has facilitated species interactions. This paper discusses the ecological and evolutionary implications of the ongoing introgression in O. esculentus, particularly under the intensifying environmental changes and continued spread of exotic species within littoral and wetland habitats where the species persists. It also recommends remedies for safeguarding these refugial populations, preserving the species’ unique genetic identity and supporting biodiversity conservation in the Lake Victoria basin.