The fisheries of Lake Victoria are highly dispersed and catch statistical information is insufficient for supporting management. Catch assessment surveys for the three riparian countries were found to be weak or inadequate and a strategy for improving this source of information is proposed. Considerable illegal fishing, using banned gears and small-meshed nets was prevalent and considered to be detrimental to the sustainability of the fishery. The principal problems underlying the poor fishery assessment were inadequate resources, poorly trained and unmotivated personnel, and externalities, such as poverty and poor employment opportunities, which override the resource monitoring and assessment mechanisms.
Lake Victoria is Africa's most important source of inland fishery production, exhibiting annual catches of ≈ 400 000 mt. The predatory Nile perch, Lates niloticus, and the herbivorous tilapiines, Oreochromis niloticus, Oreochromis leucostictus, Tilapia zillii and Tilapia rendalii, were introduced in Lake Victoria in the 1950s and 1960s. Nile perch were introduced to convert the abundant, but bony, haplochromines to fish flesh, while the tilapiines were introduced to boost the declining fishery. Since that time, the fisheries of Lake Victoria have undergone dramatic social and ecological changes. The catches increased tremendously, changing the fishery from artisanal to commercial, in turn increasing fisher income and employment opportunities. However, there was a decline and, in some cases, the disappearance of many indigenous fish species, especially the haplochromine cichlids. This reduction was attributed to overexploitation, predation, and competition and hybridization with the introduced species. The decline of the native fish species has had impacts on the trophic and ecological status of the lake. Nile perch now dominate the formerly complex food web. The loss of phytoplanktivorous haplochromines has contributed to an increase in algal blooms, reduction in water quality and occasional fish kills. Water hyacinth, Eichhornia crassipes, invaded Lake Victoria in 1988, with high rates of infestation in shallow waters and bays, which are breeding and nursery grounds for most fish species. Catches of Nile perch decreased following the infestation, while those of Nile tilapia, lung fish (Protopterus aethiopicus) and mud fish (Clarias gariepinus) increased. Haplochromines species also showed some signs of recovery. In view of all these changes, the future of the Lake Victoria fishery is uncertain.
Lake Victoria, East Africa, supports a fishery that yields about one million tonnes per annum consisting predominantly of three species, Nile Perch (Lates niloticus), Nile Tilapia (Oreochromis niloticus) and a native sardine-like cyprinid called Dagaa (Rastrineobola argentea). The non-native Nile Perch is the most valuable of these species and supports an important commercial export industry; there are fears that overfishing, due to the growth of fishing capacity, is threatening the Nile Perch fishery. Based on its economic importance and the notion that overfishing is threatening the resource, the current fishery management system was developed to control fishing capacity and effort. This system, using the concepts of co-management, where fishing communities and stakeholders participate through community organizations called Beach Management Units (BMUs) to actively manage the fishery in partnership with the central government, has been criticized that it is “fishery-based,” focusing on a single species and taking no account of ecological conditions in the lake, nor other species. A more “holistic” approach, which places a greater emphasis on changing nutrient concentrations and primary productivity as drivers of fish populations, has been proposed. Though fishery biologists and managers on Lake Victoria recognize that ecological conditions affect fishery populations, there appears to be two major challenges hindering the implementation of such approaches: first, the lack of a coherent objective of the Lake Victoria fishery, and second, the challenges associated with incorporating and implementing concepts of nutrient information and multiple species into a practical fishery management program. This article describes the current fishery co-management program to determine the feasibility of implementing a holistic approach on Lake Victoria. It is concluded that whether a management system should be “holistic” or “fishery-based” is of little importance; what is needed on Lake Victoria are clear objectives and a management plan that will enable those objectives to be achieved, utilizing both ecological and fisheries data where appropriate.
From 1999 to 2011 some regions in the Lake Tanganyika Basin experienced humanitarian crises that displaced hundreds of thousands of people to neighboring countries. When relative calm returned to the region in 2008, an influx of displaced peoples and refugees returned to the lake seeking their ancestral fishing grounds. Well-meaning non-governmental organizations and United Nations-organizations donated fishing equipment to these returning people to aid their livelihood opportunities. These fishing programs, however, increased uncontrolled fishing effort on Lake Tanganyika beyond that of previous levels, resulting in decreasing fish catches. Increased monitoring of the fishery, therefore, became essential. In 2009, as a result of uncontrolled fishing effort due to the influx of returnees, inefficient national efforts to monitor their fisheries, and the observed decline of fishery resources, the four countries bordering Lake Tanganyika (Burundi, Democratic Republic of Congo, Tanzania and Zambia) established a regional coordinating body called the Lake Tanganyika Authority to implement fisheries conservation and management measures in compliance with the Convention on the Sustainable Management of Lake Tanganyika. To inform and enable a fisheries monitoring program on Lake Tanganyika, the Authority conducted a lake-wide fisheries frame survey in 2011 to inventory the number of fishermen, fishing units and fisheries infrastructure around Lake Tanganyika. When comparing the 2011 frame survey with data from a similar survey conducted in 1995 (the two most extensive studies to date on Lake Tanganyika), results revealed troubling trends in fish capacity, including: an increase in illegal fishing gear, a doubling of the total number of fishermen and fishing units, and a decline in catch rates since 2002 (based on Burundi data which has been consistently collected). This article analyzes the trends of the Lake Tanganyika fishery, including: fishing effort, the changing uses of gear, and trends in employment in the fishery. Because of the observed increase of fishing capacity (e.g. the numbers of vessels, licenses and fishermen), this article addresses whether an effective fishery management program can be implemented on the lake. Past management efforts have been made from within the basin by the individual countries (Burundi, Democratic Republic of Congo, Tanzania and Zambia), transnational organizations (Food and Agriculture Organization), and the Lake Tanganyika Authority. Using current notions of fishery management on large lakes in the region and ideas from a case study from Gambia, West Africa, this study suggests that effective fishery management on Lake Tanganyika requires the adoption of a formal Monitoring, Control & Surveillance system, community surveillance, an improvement in licensing systems, and a limitation in the number of fishermen and fishing units.
The decline in fish species in Lake Victoria is one of the largest documented losses of biodiversity in an ecosystem. The reduction in species in the lake was attributed to overexploitation through increased fishing capacity, use of illegal fishing gears and poor enforcement of regulations. Introduction of the predatory Nile perch is blamed for the decline of the native species, especially the haplochromine cichlids. The native tilapiines, Oreochromis esculentus and Oreochromis variabilis, declined due to hybridisation and competition with the introduced Oreochromis niloticus. Diversity loss in haplochromine cichlids has also been attributed to hybridisation caused by increased water turbidity, which reduces visibility in recognising conspecifics during breeding. Degradation of the environment through poor farming patterns and waste disposal has led to increased nutrients into the lake, in turn leading to changes in water quality, increased algal blooms and subsequent anoxia which led to frequent fish kills in the 1990s. However, recent resurgence of haplochromines thought to be extinct, disputes the fact that extinction of several species occurred. Though not denying that a drastic reduction in the number of native species occurred, the much hyped extinction could be a result of a lack of adequate information on taxonomy and ecology of the haplochromines as well.
This study reports on the population parameters, catch distribution and feeding ecology of Nile tilapia (Oreochromis niloticus) from bottom trawls and commercial catches obtained in the Kenyan portion of Lake Victoria during 1997-2006. The population parameters were analysed using the FAO-ICLARM stock assessment tool (FISAT). The fish biomass and the food ingested by the fish were estimated using the swept area and point methods, respectively. Immature fish comprised ഠ70% of the total fish population. The asymptotic length, maximum weight, maximum age, exploitation rate (E) and length at 50% maturity of Nile tilapia have decreased, whereas the growth curvature and fishing mortality have increased. The commercial catches increased from 13.93 t in 1997, to 23.70 t in 1999, decreasing thereafter to 18.73 t in 2005. The bottom trawl catches increased from 46.90 kg ha -1 in 1997, to 401.48 kg ha -1 in 2000, decreasing thereafter to 15.57 kg ha -1 in 2006. The major food items ingested by the fish were algae, insects and other fish. Population parameters, and the catch and diet of O. niloticus, have changed over the years in Lake Victoria. The population characteristics suggest a population under stress, attributable to intense catch exploitation. Even under intense exploitation (E = 0.68), however, the mature fish constituted ഠ30% of the population. The commercial catches are still high, indicating a very resilient fishery. Nevertheless, despite this resilience, the future of Oreochromis fishery is threatened by increased fishing capacity in the lake, and there is need to re-evaluate the effectiveness of current fishery management measures, with the goal of possibly adopting new measures. Enactment of new fishery policies also should provide for co-management to enhance the management process. Furthermore, there is a need to reduce fishing capacity and illegal fishing methods, and to seek alternative livelihoods for lake fishers and other stakeholders.
Four decades after the initial export of Nile Perch from Lake Victoria, which reached an annual maximum harvest of 330,000 tons in 2000 (LVFO, 2009), Nile Perch resources are under pressure. With a form of co-management in place, it is not clear who is responsible for resources management. The fishers claim the Governments are responsible and the Governments say that the fish export industry is responsible. Results of six years of research led the Council of Ministers of the Lake Victoria Fisheries Organization in 2003 to endorse the recommendation to enforce drastic measures. When the measures came into force they were strictly adhered to, but with time, the authorities unwillingly relaxed them until draconian measures then had to be taken. Identical measures were adopted by the Council in 2009 and this resulted in the professional fish export associations rigidly maintaining one portion, while claiming that no scientific evidence existed for the other part. The co-management system making use of Beach Management Units (BMU) is well developed on Lake Victoria, but has only been partly introduced to the shores of Lake Tanganyika, where certain management structures have existed for many years. This article discusses how the state of the optimum fish stocks could be regenerated, but notes that other external factors may also play roles (including climate change). On Lake Tanganyika an industrial fishery was operational in the northern part of the lake from the mid-1970s to the mid-1990s, which gradually moved southwards with time and was outcompeted by the emerging artisanal fishery, whose effort is still increasing. Whilst riparian Governments subscribe to international action plans, messages have to be put across to the fishing communities about regeneration of lake ecosystems.
The fisheries of Lake Victoria have always been dynamic and the relevant authorities have continually tried to manage them. During the second half of the last century, numerous changes took place and fisheries managers had to cope with influences other than exploitation, including species introductions, invasive weeds, lake level rise, changes in water quality, and illegal fishing practices. These have influenced the way the fisheries have been managed. In the 1920s, measures existed to manage the fisheries of Lake Victoria. In those days, a minimum net mesh size of one inch was in place, as well as certain restrictions for trawling and other fishing methods. Over the years, certain fishing gears and methods have been banned; some bans were lifted and then reimposed; minimum mesh sizes have shifted as a result of changing species compositions and changing needs to protect components of the stock. More recently, the fishery has been subjected to a series of bans on export to the European Union because of outbreaks of cholera and fish poisoning practices. This article presents an overview of fisheries management on Lake Victoria, the successes and failures, impacts of fish exploitation and invasive weeds on species diversity, results of a major research project on the lake to assess the status of the fisheries, and the way forward.
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