The exploitation of small pelagic fishes of the great lakes of Africa with reference to the mukene (Rastrineobola argentea) fishery of the northern waters of Lake Victoria

Small pelagic fish species have ultimately become important on most of the Great Lakes of Africa, especially after the depletion of the larger, initially preferred fish species. In Lake Victoria, the small pelagic cyprinid Rastrineobola argentea is now the only abundant native species supporting a fast growing light fishery. In Pilkington Bay, off Lingira Island the artisanal light fishery is well established and in the last two years this bay has witnessed a sharp increase in the fishing effort. This has been followed by a modification of fishing method and a reduction in the mesh size of nets used. R. argentea now caught from this bay consist of mainly juveniles and this could result into localized recruitment overfishing. Drawing examples from what is happening to the fishery in Pilkington Bay, it is necessary to carry out research on the stocks, gear and suitable fishing crafts before light fishing spreads to most parts of the lake.

The future prospects for the Lake Victoria fishery

The annual fish yields from Lake Victoria have been increasing when the species diversity was dramatically declining. The new fishery is dominated by the introduced predator (Lates niloticus Linne), the exotic herbivore (Oreochromis niloticus Linne) and an indigenous zooplanktivore (Rastrineobola argentea Pellegrin). While the three predominant fish species could sustain the high catch levels, the future viability for the fishery will depend on prudent exploitation regimes and effective management and conservation strategies.

Towards balanced exploitation and management of the fishery resources of Uganda

A casual study of the hydrological map of Uganda would convince every serious fisherman and fisheater that he is most favoured to be in Uganda. The extent and distribution of the country's aquatic system plus the rich variety of fish species there is promises a fishery potential of considerable magnitude: The open waterways comprised by the Uganda portions of Lakes Victoria, Albert and Edward; and Lakes Kyoga, George plus minor lakes Wamala, Kijanebarora, mutanda, etc. occupy about 15% of the total surface area (91,000 m2; Depart. Land Survey, 1962). Most of the nation's fish supplies are currontly from this source. 1.2. A rich network of permanent and seasonal rivers and streams filling and/or emptying various water systems covers most of Uganda. This aquatic network is associated with a fish fauna whose immense significance as a source of protein is perhaps better appreciated by the local subsistance fisherman and consumer than by the fisheries scientist and manager in this country. Many species of this fish fauna have strong affinities with the open water systems while some are typically riverine. 1.3. Then there are wetlands composed mainly of expanses of swamp, but including some areas of bog. These cover about 2% of the country. While the variety of fish fauna found here is limited by the rather hostile nature of the environment (comparatively de-oxygenated under a canopy of dense stands of emergont vegetation) several specialised fishes e.g. Clarias spp. and Protpterus aethiopicus (Kamongo) occur here. Availability of permanent and seasonal sources of water, well distributed throughout most areas of Uganda, opens up immense potential for a variety of aquaculture practices. However, while active exploitation of much of these fishery resources is currently underway, important questions regarding the magnitudes of the various resource potentials and dynamics, and about suitable levels and modes of exploitation, are yet unanswered. These gaps in knowledge go about the fishery resources of Uganda would hinder formulation of adequate development and management schemes. This short paper examines some of the above problems and suggests some approaches towards balanced oxploitation and management of the fisheries of Uganda.

Cast-net fishery on northern portion of Lake Victoria and upper Victoria Nile

This project survey on cost-net was conducted at the Northern portion of Lake Victoria and Upper Victoria Nile. The selected fish -Landing sites, where sampling exercises were carried out include: Loco, Jinja pier (covering Lake Victoria) and Railway bridge, New bridge and Kalange (covering upper Victoria Nile). Research was focused on the cast-net design, target commercial fish stocks, impact of cast-net on the fish stocks, mesh-size and techniques ofcast-netting. The research results show that cast-net fishery destroys fish breeding and nursery grounds and other fish ecosystem. The gear targets Oreochromis niloticus and Occassional by catches e.g. Lates niloticus, Mormyrus Kannume Bagrus docmak and Clarias gariepinus. The multi-panel cast-net of mesh-sizes ranging from i (5lmm) to 6' (152mm) were adaptable by fishermen but they mostly caught immature fish. Nevertheless, this gear showed highest efficiency compared to other gears used at the project area. These research results will be useful to researchers, extension workers and Fishenes, students under taking special research or study on this gear.