Title
Comparative age and growth of Nile tilapia (Oreochromis niloticus L.) in lakes Nabugabo and Wamala, Uganda
Author(s)
Bwanika G.N., Murie D.J., Chapman L.J.
Published
2007
Publisher
Hydrobiologia
Abstract
Age and growth of Nile tilapia (Oreochromis niloticus) from Lake Nabugabo and Lake Wamala, Uganda, were determined using cross-sectioned sagittal otoliths. Marginal-increment and edge analyses of Nile tilapia otoliths from Lake Nabugabo indicated formation of two annuli per 12-month period. Opaque zones associated with faster growth were observed between April and June and between September and December, coincident with the two rainy seasons of the year. Within both lakes, males were larger at age than females. Nile tilapia from Lake Nabugabo, however, had faster growth rates than Nile tilapia from Lake Wamala, and fish >3 years old from Lake Nabugabo were larger at age than those from Lake Wamala. Ages ranged from 0 to 8.0 years for Nile tilapia from Lake Nabugabo, and from 0.5 to 6.5 years for tilapia from Lake Wamala. Differences in the patterns of growth in Nile tilapia between lakes may reflect, at least in part, the relatively energy-rich omnivorous diet of Nile tilapia in Lake Nabugabo versus a phytoplanktivorous diet in Lake Wamala. Diet differences of Nile tilapia between the two lakes are ascribed to trophic changes in the lakes due to the introduction of Nile perch (Lates niloticus) into Lake Nabugabo but not Lake Wamala. Alternatively, the greater exploitation of Nile tilapia in Lake Nabugabo may have resulted in increased growth rates, whereas Nile tilapia in Lake Wamala may be subject to slower, density-dependent growth. © 2007 Springer Science+Business Media B.V.
Keywords
Biodiversity; Lakes; Microorganisms; Nutrition; Population dynamics; Lake Victoria basin; Nile perch; Otoliths; Tilapiine fish; Ecology; age determination; food preference; growth rate; lake ecosystem; longevity; omnivory; otolith; perciform; seasonal variation; Africa; East Africa; East African Lakes; Lake Nabugabo; Lake Victoria; Lake Wamala; North Buganda; South Buganda; Sub-Saharan Africa; Uganda; Lates niloticus; Oreochromis niloticus; Tilapia

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PUB10684