De heer Eshete Dejen Dresilign : The small barbs of a tropical highland lake (L. Tana, Ethiopia)

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2 Sep 2003 16:00
Unit: Wageningen University
Location: Aula (gebouw 362), Gen. Foulkesweg 1, Wageningen
Co Promotor: dr. F.A. Sibbing, dr. A.J. Vijverberg (NIOO-KNAW, Nieuwersluis

 Lake Tana is by far the largest lake of Ethiopia and source of the Blue Nile. By feeding on zooplankton, small barbs (< 10 cm) occupy a central position in Lake Tana’s ecosystem. Catching them could release pressure on the overexploited, unique species flock of large barbs (up to 100 cm). Aiming at small barbs, we need first to assess its possible impact on the food web and productivity. To advise on sustainable management, the biology and ecology of the small Barbus species in Lake Tana was investigated: identification, feeding biology and major food source (i.e. zooplankton) in the environment, their reproductive biology, individual growth and productivity. Resource partitioning with competitors (juveniles of the large barbs and a zooplanktivorous larger barb, Barbus brevicephalus) involve space and food. From the biomass and production of small barbs, the biological production was estimated and their annual potential for fishery (4000 tons). The possible consequences of such a fishery on the large barbs, preying on small barbs, and on lower trophic levels of the Lake Tana food web (e.g. zooplankton, phytoplankton, detritus) are explored.
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