Acere, A.; Mwene-Beyanga, P.
Lake Albert/Mobutu lies along the Zaire-Uganda border in 43/57 per cent ratio in the faulted depression tending south-west to the north east. It is bounded by latitudes 1o0 n to 2o 20’ N and longitudes 30o 20’ to 31o 20’E.
It has a width varying from 35 to 45 km (22 to 28 miles) as measured between the scarps at the lake level. It covers an area of 5600km2 and has a maximum depth of 48m. The major inflow is through the Semiliki, an outflow of Lake Edward, Muzizi and Victoria Nile draining lakes Victoria and Kyoga while the Albert Nile...
The dramatic decline in fish species diversity in Lake
Victoria has been attributed to predation by Nile perch, Lates niloticus Linne, without sufficient justification. Exploitation, interspecific competition and hybridization had profound impact on the decline of the indigenous commercial fish species. The roles of exploitation, competition and hybridization, and of predation by the Nile perch on changes in species diversity have been discussed. Lates was largely responsible only for the decline of the haplochromine stocks.
The food of the Nile perch has changed since its introduction
into Lakes Victoria, Kyoga and Nabugabo and stabilized on
Caridina nilotica, Anisopteran nymphs, Rastrineobola argentea,
Nile perch juveniles, and tilapiines. For the Nile perch to
sustain production in these lakes, its is important that these prey species are properly managed.
Lake Victoria had a complex multi-species fishery dominated until the late 1970s by the tilapiine and haplochromine cichlids but with important subsidiary fisheries of more than 20 genera of non-cichlid fishes. Since the 1980s, however, the fishery has been dominated by the Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus eduardianus) both introduced into the lake during the late 1950s and early 1960s and Rastrineobola argentea, a pelagic cyprinid. Although the actual landed commercial catch figures from the Uganda sector of the lake point to the increased landings since 1984, the catch rates in the experimental trawl fishery and mean...
Okaronon, J.O.; Akumu, J.; Bassa, S.
Lake Victoria had a multi-species fishery dominated until the 1970s by the tilapiine and the haplochromine cichlids (Kudhongania and Cordone, 1974). From about 1930 to 1960, the fisheries of Lake Victoria were managed by controlling the mesh size of gill nets. Gill nets of stretched mesh sizes less than 127 mm (5 inches) were prohibited as they cropped immature Oreochromis esculentus (Ngege), the most important commercial species on the lake (Graham, 1929). The catch per night in the legal 127 mm mesh nets was over 30 fish of O. esculentus prior to 1921 but dropped to 6 and 1.5 fish...
Odongkara, K.; Kyangwa, M.; Nyapendi, A.; Gonga, J.; Atai, A.
The purpose of this paper is to review selected socio-economic aspects of the Kyoga basin lakes with a view to assessing, the potehtials within the fishing communities for participatory management and poverty eradication. This paper is based on information obtained from three categories of
activities. First a review of existing data and reports was undertaken to establish existing knowledge on the subject and identify the gaps.
Kamanyi, J.R.; Okaronon, J.O.
The fundamental purpose of fisheries management is to ensure sustainable production over time from fish stocks, preferably through regulatory and enhancement actions that promote economic and social well being of the fishers and industries that depend on the resource. To achieve this purpose, management authorities must design, justify and administer (enforce) a collection of restraints on fishing and fishery-related activities. Productivity and management of the fisheries should be based on the understanding that they are complex and dynamic systems. Physical, chemical and biological components support a community of organisms that is unique to the these systems. All these components are...
Ogutu-Ohwayo, R.; Hecky, R.E.
Fish introductions have been made from small fish ponds to the largest lakes in Africa. The primary intent of these introductions has been to sustain or increase fish production, although some introductions have been made to develop sport fisheries and to control unwanted organisms. Some of these introductions have fulfilled their objective in the short term, but several of these "successful" introductions have created uncertainties about their long term sustainability. Lates niloticus, Oreochromis niloticus, O. leucostictus, Tilapia melanopleura and T. zilli were introduced into lakes Victoria and Kyoga in 1950s and early 1960s. By the 1980s O. niloticus and O....
The major dangers facing the resources of the Great Lakes of Africa include over exploitation, falling species diversity, accumulating pollution, and a probable decline in fishery productivity. These dangers may be viewed as accentuated by:
i) Inadequate scientific knowledge on the exploited resources ii) Reluctance to apply even the limited scientific information available, by fishery administrators
iii) Constant increase in the demand for fish and other aquatic resources.
iv) Lack of commitment to active collaboration and co-operation by riparian states regarding development and management of the shared resources.
This paper discusses the above factors in relation to the dangerous trends facing the resources of...
Orach-Meza, F.L.; Coenen, E.J.; Reynolds, J.E.
Uganda's fish production has shown a substantial increase from a level of 61,500 tonnes in 1961 to a total of 214,302 tonnes in 1988. During this period significant changes also occurred in species composition, fishing factors, and patterns of utilisation. This paper briefly summarises the
fisheries of Uganda's great lakes and reviews past and present trends in their exploitation, as reflected in available catch and effort data collected through the Fisheries Department statistical reporting system.
This paper is based on a two year's intensive statistical data collection survey on Lake Kyoga, observations made on Lake Victoria over the last decade occasional visits on Lake Albert (Mobutu) and Lake Malawi. World over, scientists have kept doubting the fisheries statistical figures
presented by various African countries. Some countries fail to present any figures. This paper, therefore, narrates most of the causes and possible solutions to those problems.
The present study was undertaken to try and find out why Lates niloticus and Oreochromis nilolicus have managed to co-exist in Lake Victoria (Kenya sector). The study is considered to be of tremendous scientific value not only because Lates has been accused of preying on the cichlid stocks in L.Victoria but also for considering suitable management approaches to maintain viable fishery resources on long-term basis. The results presented are preliminary and the final detailed results will be presented later when the survey will have been accomplished.
A detailed study of the early life of fishes forms one of the very important aspects with respect to recruitment mechanism and proper uneterstanding of the dynamics leading to sustainance of fish populations. It should be the central theme of the fisheries biologist and managers to extract the bilogical information relevant to the proper understanding of this part of the population. A number of studies in the Mwanza gulf and Lake Victoria have emphasized the need to monitor the fishery by conducting observations of stock size, migration, catch effort data and growth of big specimen (Acere 1981, Goudsward et al...
Bugenyi, F.W.B; Magumba, K.M.
In this paper, we try to briefly review the current physico-chemical data pertaining to Northern Lake Victoria which could eventually be used to explain the following:-
(a) whether there bas been a change of the dissolved organic nutrient cencentrations when compared with the pre-perch period, (b) the specific point sources of the influent nutrients and other chemicals and how they correlate with changes in algal productivity, and (c) whether the data can contribute to the validation of the Lake Victoria ecological model developed by Jorgensen at al. (1982).
In Lake Victoria and other tropical inland water bodies, the study of secondary production has lagged behind other aquatic studies mainly because of inadequate research funding. Lack of basic scientific knowledge of such a major ecosystem component has greatly limited the understanding and management capacity of a vital regional fishery resource. This paper reviews the major roles played by various invertebrate organisms in the functioning of aquatic systems and the contribution of secondary production studies to fishery production assessment and management.
The commercial fisheries of Lake Victoria are presently dominated by three species: the stocked
Lates niloticus and Oreochromis niloticus, and the endemic cyprinid Rastrineobola argentea. The three comprise at least 90% of the commercial catch while the rest of the endemic species mostly occur as by-catch (incidental catch) except in localised areas.
Apart from being a major source of food, the three species especially the Nile perch represent
the usually recognized main forms of predation, As they exert a "top-down" effect on production,
they are important in the trophic dynamics of the Lake Victoria ecosystem. However, another form of predation which is usually...
The data from the able sources has been used in this paper to make observations on the exploitation of the fish stocks in Lake Victoria since 1981. The paper focuses on species composition of the catch, catch rates, average size of the individual fish landed and fish production. On the basis of these parameters and developments in the fishery, the paper also presents some observations and comments on the future prospects of the fish stocks in the lake.
Fisheries plays a significant and important part in the economy of the country contributing to foreign exchange, food security and employment creation. Lake Victoria contributes over 50% of the total annual fish catch.
The purpose of fisheries management is to ensure conservation, protection, proper use, economic efficiency and equitable distribution of the fisheries resources both for the present and future generations through sustainable utilization.
The earliest fisheries were mainly at the subsistence level. Fishing gear consisted of locally made basket traps, hooks and seine nets of papyrus. Fishing effort begun to increase with the introduction of more efficient flax gillnets in 1905....
Over the years, degradation of the lakeshore resources has been going on due to human induced activities. Human activities notably house construction, fish smoking, boat construction and cooking at the landings impact the tree and forest cover along the lakeshore and Islands. The survey was conducted in ten districts surrounding Lake Victoria and the landings sampled were selected with the help of the District Fisheries Officers. Data was obtained from selected fishermen and Key informants at these landing sites. The study examined the extent of knowledge on importance, utilization, threats and conservation of trees/forests at the landings. Results showed that...
There is little doubt that the exploitation of the current
fisheries of Lakes Victoria and Kyoga requires close monitoring with a view to enforce adherence to prudent management practices. Many indigenous fishes have gradually disappeared from the commercial fishery of both lakes. In the Uganda portion of Lake Victoria for instance Okaronon and Wadanya (in press)
have shown that:-
1. The once preponderant haplochromiine taxon ceased to
feature in the commercial catches in 1979.
2. The lung-fish (Protopterus aethiopicus) which
formerly contributed significantly to the commercial landings had declined to minor species status by the mid 1980s.
3. The catfishes Clarias mossambicus and Bagrus docmac,
formerly major fish...