Population characteristics of Oreochromis esculentus in the Victoria and Kyoga lake basins. Implications for conservation and improvement of the stocks
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Date
2006
Journal Title
Journal ISSN
Volume Title
Publisher
Blackwell Publishing Ltd, Afr. J. Ecol.
Abstract
The tilapiine fish Oreochromis esculentus, is endemic to only lakes Victoria and Kyoga and a few satellite lakes in the two lake basins. It was the most important commercial fish species during the first half of the 20th century in the two lake basins but because of over-exploitation and competition with introduced tilapiines, its stocks declined and, by 1980s, O. esculentus was virtually absent from the two main lakes. Lakes Mburo, Kachera, Kayanja and Kayugi in the Lake
Victoria basin, and Nabisojjo, Kawi and Lemwa, in the Lake Kyoga basin, where remnants of the species survived were investigated using experimental fleets of gillnets from 1997 to end of 2002 with the objective of determining the species length frequency distribution, condition factor, feeding and breeding to guide its management, conservation and enhancement.
Fish caught in Lake Kayugi, where diatoms dominated in the stomach contents attained the largest size, were most fecund and had a high value of condition factor K.These findings suggest that diatoms were vital in the survival of O. esculentus. However, with the recent shift of algal communities from diatoms to blue-green algae in most aquatic systems, assimilation of blue-green algae by O. esculentus should be investigated.
Description
The field work was funded by the Lake Victoria Environment Management Project (LVEMP) being funded by the GEF/World Bank, through the Fish Biology and Biodiversity Conservation Sub-Component at FIRRI
Keywords
conservation, improvement, Oreochromis esculentus