Title: An assessment of the effect of the closed seasons on abundance of the Silver cyprinid, Rastrinebola argentea, in Lake Victoria

Author(s): Robert Wanyama
Final project
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Lake Victoria is currently dominated by the introduced Nile perch, (Lates niloticus), Nile tilapia (Oreochromis niloticus) and the endemic cyprinid Rastrineobola argentea. R. argentea is second only to Nile perch in terms of commercial importance. With the recent declining trends in the catches of Nile perch and most other fish species in the lake, interest has gradually been shifting to the exploitation of R. argentea. From time to time Lake Victoria partner states have been implementing management measures aimed at ensuring sustainable utilization of the fisheries. One such measure was to implement a yearly closed season for fishing of R. argentea for four months period, starting in 2001. However this ban was only implemented by Kenya. The objective of this study is to assess the effect of the closed seasons in the Kenyan part of the lake on the abundance of R. argentea. Catch, CPUE and biomass data were analysed to establish trends between 1999 and 2011, for the Kenyan and Ugandan portions as well as the entire lake. The results indicated an increased biomass not only on the Kenyan side, where closed seasons are implemented, but also in the entire lake. This indicates that factors other than fishing, such as environmental and ecological changes play a crucial role in the fluctuations of R. argentea abundance in the lake. This study highlights the need for more information on the biology of R. argentea in order to develop management strategies. Furthermore, since this is a short-lived species, a total ban should be replaced with a more focused restriction targeting critical breeding areas and nursery grounds in cooperation with fishers.

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