Abstract:

The fisheries resources of Lake Victoria support the livelihoods to the lakeside rural communities and are vital to the economies of Kenya, Tanzania and Uganda, especially through fish exports. Management decisions to enable long-term sustainable exploitation of these fisheries require appropriate knowledge of the fishing effort and catch statistics, as these are pertinent for evaluating the fish stocks and future prospects of the fishery. Catch assessment programmes in the Ugandan part of the lake, which should provide this type of information, collapsed in the late 1980s. This study evaluated the current status of fishing effort and fish catches and their implications for the management of the fisheries in the Ugandan part of Lake Victoria. Historical trends in fishing effort and fish catches, total fishing effort in 1990 and 2000, and the current status of fish catch-effort, in the Ugandan part of the lake, were examined. The findings revealed massive increases in all aspects of fishing effort over the last decade. Fishing boats approximately doubled, from 8000 to 15 462 boats, and gillnets almost quadrupled, from 84 977 to 294 529 nets, between 1990 and 2000. Gillnet mesh sizes declined from mainly 203 and 178 mm to <152 mm, and illegal gillnets <127 mm mesh size increased from 5 to 18.6%, between 1990 and 2000. Illegal gillnets constituted 53 and 23% of nets in parachute and paddled Sesse boats (small boats that operate in inshore areas) but only 1.9% in motorised boats. Other illegal gears, especially beach seines, operated inshore and indiscriminately catch juvenile fish, also increased considerably. These changes in fishing effort were coupled with declining catch per unit of effort and are considered indicators of a declining fishery, suggesting that the current fishing effort is not sustainable. The present exploitation rates and fishing mortalities of Nile perch (Lates niloticus L.) and Nile tilapia (Oreochromis niloticus L.) in the Ugandan waters were found to be excessive and require large reductions of fishing effort to achieve optimum yield. The use of illegal fishing gears and the overall fishing effort is highest in the eastern zone of the Ugandan waters, and in Kenyan waters at the regional level. Fishing strategies in the gillnet fishery, the predominant fishery for Nile perch and Nile tilapia, vary with boat type, suggesting that the regulation of fishing effort should be tailored to category of boat. Selection characteristics of the main fishing gears/methods in the Nile perch fishery suggested that fish above the minimum recommended 50 cm TL could be obtained from catches of drift gillnets with the minimum mesh size at 152 mm. The present long line fishery is largely non-selective and should be discouraged. Illegal, active fishing with gillnets and cast nets, which disrupt breeding of tilapiines inshore, prevail in the Nile tilapia fishery, and are indicative of overexploitation. The present fishing effort for Rastrineobola argentea in Ugandan waters approximates to the maximum sustainable yield, but is basically restricted inshore, where the 5-mm mesh size mosquito nets used catch mostly juveniles. Expansion of fishing effort without endangering sustainability in this fishery would probably be viable with reorientation of fishing to offshore stocks. To reduce fishing mortality in the short term, in the Nile perch and Nile tilapia fisheries, immediate interventions should control the size of fish caught. This should be through enforcement of existing legislation on fishing gears that target the younger life stages of fish and regulating the size of Nile perch purchased by fish processing factories. In the long term, the quantities of fish processed by factories should be regulated by a quota system, consistent with the fisher}' production potential of the lake. Long lining should be discouraged pending further scientific investigations of hook selectivity characteristics. The minimum gillnet mesh size limit should be maintained at 127 mm in paddled boats but raised to 152 mm in motorised boats to reduce overall pressure on juvenile Nile perch and competition between the large-scale and small time operators, and promote social objectives of the fishery. Access to the fisheries should be limited because this is the overriding factor contributing to the present unsustainable status. Fisheries statistical data collection in Uganda (and Tanzania) should be revived and fisheries data, collection and reporting systems should be harmonised around the lake. The process of streamlining institutional mechanisms and legal instruments under which fishing communities will play important roles in fisheries management (co-management), should be accelerated. However, for any institutional arrangement to succeed in managing the fisheries of Lake Victoria, mechanisms for sustainable funding of fisheries activities should be established.