Abstract:

Fish species diversity in Lake Nabugabo, Uganda, has declined following establishment of
the introduced fish species in the lake. Most of the native fish species have disappeared and
the lake is now dominated by the introduced Nile perch, Lates niloticus and the Nile tilapia
Oreochromis niloticus. The dominant native fish species include Synodontis aji-ofischeri, Schilbe
intermedius, Rastrineobola argentea and Brycinus sadleri. Some of the native fish species that
have disappeared from Lake Nabugabo were reported to occur in lakes Kayugi and Kayanja,
which are adjacent to Lake Nabugabo but separated from it by extensive papyrus swamps. The
Nabugabo lakes are satellite water bodies in the Lake Victoria basin, which is known to have
experienc~d fish species changes due to the introduction ofthe Nile perch Lates niloticus during
the 1960s. The Nabugabo lakes comprising of Lake Nabugabo main, and the smaller lakes
Kayanja and Kayugi were investigated between 2000 and 2002 with experimental gillnetting
to evaluate the potential of these lakes in conservation offish species diversity. Results show
that some native fish species especially Oreochromis esculentus, and Oreochromis variabilis
and the haplochromine cichlid Prognathochromis venator that have disappeared from Lake
Nabugabo still occur in Lakes Kayanja and Kayugi. Inshore habitats with macrophyte cover
were also found to be important habitats for the endangered native fish species in the Nabugabo
lakes. These lakes and inshore habitats need to be protected to conserve the endangered native
fish species and to reduce further decline in fish species diversity.