Predation by Nile Perch Lates Niloticus, (Linne) Introduced Into Lake Kyoga (Uganda) and its Effects on The Populations of Fish in the Lake.

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University of Dar es Salaam
The Nile perch lates niloticus was introduced into Lake Kyoga amidst fears that it might feed on and damage populations of the commercially important fish. Following this introduction, populations of the native fish species of the lake declined and, in some cases, completely disappeared. The food and feeding habits of the Nile perch were investigated to estimate the extent of predation upon the populationsof fish in the lake. Past trends and the present state of Lake Kyoga fishery has also been analyzed.The Nile perch feed on invertebrates changing to a piscivorous diet with age. The invertebrates consisted of copepodschaoboruspovilla and other Ephemeropterans, Zygoptera, Anisoptera, Hemiptera, Chironomids and prawns.The fish prey was dominated by Engraulicypris argenteusand Sarotherodonniloticus with Haplochromis s pp. and L. niloticus forming a less significant contribution to the diet. The Nile perch feed at night and appears to feed only once over the 24-hour cycle. The stomach contents weigh 1.2-2.6% the weight of the predator. The Nile perch can ingest fish up to a third its own length. All the available sizes of Haplochromis spp. and E. argenteus, S.niloticus up to 43 cmand L.niloticus up to 26 cm were found among stomach contents.L. niloticus, S.niloticus and E.argenteus were the most abundant and widely distributed fish in the lake. Most native fish species are rare. Fish catch statistics gave a negative correlation between increase in Nile perch population and the decline in that of the native Sarotherodon species. Since its introduction, L.niloticus has shifted from one prey to another, cannibalism has increased and the condition factor of the predator has decreased. L.niloticus therefore appears to have caused considerable damage to the populations of fish in the lake and suggestions relating to its management are made.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QL638.P4O55)
Fish, Culture, Diseases and pests, Lake Kyoga, Perches (Zoology)
Ohwayo, Richard Ogutu- (1988) Introduced Into Lake Kyoga (Uganda) and its Effects on The Populations of Fish in the Lake, Master dissertation, University of Dar es Salaam