Browsing by Author "Shechonge, Asilatu Hamisi"

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    Biogeography, diversity and conservation of Tilapia genetic resources in Tanzanian watersheds
    (University of Dar es Salaam, 2019) Shechonge, Asilatu Hamisi
    Tilapia are a group of freshwater fishes that are widely distributed across Africa and are increasingly cultured species as a major source of food. Tanzania is a global hotspot for biodiversity within the genus Oreochromis, with 20 of 32 described species, some considered to be threatened by the IUCN. This work in this thesis reports the current distributions of tilapiine genus Oreochromis in Tanzania, estimates the extent of hybridization between native and non-native species, and quantifies the dietary niches of both native and non-native species within Mindu and Kidatu reservoirs. The work in the thesis also describes the genetic structure of Nile tilapia populations including Lake Tanganyika and other parts of the country, and investigates the relative growth rates of native and non-native species. The approaches used include field surveys, morphometrics, molecular genetics, stomach content analyses, stable isotope analyses and scale growth measures. In total 14 species of Oreochromis species were identified in their native ranges, while three species were found to have established far beyond their native ranges including Nile tilapia (Oreochromis niloticus) and blue-spotted tilapia (Oreochromis leucostictus). The results provided clear evidence of hybridization between native and invasive tilapia in Tanzania. The findings and recommendations are discussed in detail within papers and manuscripts. Measures to conserve the genetic diversity of native species are recommended.