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LAKE VICTORIA
Geophysical characteristics
Lake Victoria is the world’s largest tropical lake, the largest lake in Africa, and the second largest in the world.
The environment and resources of the lake have changed especially since the beginning of the 20th century. These changes provide a classical example of what can take place in other lakes in Africa with increase in human activities and can help in identifying management options and put in place governance systems.
The lake is shared between Kenya, Uganda, and Tanzania with its basin stretching to Rwanda and Burundi.
The Lake has at least ten major in flowing rivers (Kagera, Sio, Nzoia, Yala, Nyando, Sondu Miriu, Migori, Mara, and Katonga) and one out flow (the Nile).
It has a large catchment area of 193 km2, long shoreline of 3,440 km, is relatively shallow compared to similar large lakes (average depth of 40m and a maximum depth of 80m), and has the highest number of large rivers among African lakes, the highest number of large urban areas in its basin and very high human population density in its catchment which makes it highly vulnerable to environmental changes.
The lake dried up about 17,300 years ago, and refilled about 14,700 years ago
Demographic characteristics
The Lake Victoria basin has a population of 40 million with the highest population density among all African lakes which in some places exceeds 1000 people per km2.
Nearly 50% of the 40 million people in the basin live on < $1.25/day.
The GDP in the basin is 277-343$
Sanitation is generally poor and many people do not have access to clean water.
There are high incidences of water related diseases such as malaria, bilharzia and HIV/AIDs.
The lake is an important transport route linking East African States.
Fishes and fisheries
The lake had 12 families of fishes comprising of 14 non-cichlid species 29 of them endemic and over 500 cichlid species, 99% endemic.
Fish species composition and diversity, and fishery yield of Lake Victoria has changed over time.
Stocks of the larger size native fish species >20cm declined and some collapsed during the first half of the 20th century due to excessive fishing effort.
Non-native fish species (Four tilapiines and one predator, Nile perch) were introduced into the lake to boost fishery production.
Establishment of introduced fishes increased fishery yield creating the largest inland freshwater lake fishery in the world, which increased from about 100,000 tons before establishment to one million tons of fish annually at its peak dominated initially by the introduced Nile perch and subsequently by a small native pelagic cyprinid which contributed about 45% of the catch.
Nile perch, Nile tilapia, and Silver cyprinid (Mukene/Dagaa/Omena) have become the dominant fish species.
The fishery that emerged from these changes employed ~200,000 fishers and up to 700,000 along the value chain.
Predation by the Nile perch contributed to extinction of about 200 of the >500 haplochromine species while the introduced tilapias contributed to the collapse of remnants of native tilapias which had been depleted by overfishing.
There has been a resurgence of some haplochromine species but these are dominated by a few zooplanktivores which have undergone adaptive radiation to adapt to new conditions.
Cage aquaculture has been introduced on the lake, is growing rapidly and provides an alternative fishery livelihood but needs to be practiced using best management practices to avoid negative impacts on the lake environment.
The lake habitat
The lake was generally healthy during the first half of the 20th century with the water column mixed and well oxygenated to the bottom for most of the year.
Human induced climate warming which intensified around 1970 warmed the lake and changed its mixing dynamics that triggered ecosystem changes especially after 1970s.
There was an increase in stratification and anoxia.
The concentration of phosphorus doubled, silicon decreased 10 times, and nitrogen became deficient as the increase in phosphorus did balance the available nitrogen.
Phytoplankton productivity doubled, algal biomass increased four times, water transparency decreased and algal species composition shifted from dominance of diatoms to blue green algae which include toxic forms.
The zooplankton composition changed from dominance of larger calanoid copepods to smaller cyclopoid copepods and the macroinvertebrate community from Chaoborids to Chironomids and the prawn, Caridina nilotica.
The lake was in 1989s infested by an invasive weed, water hyacinth which affected lake especially the shallow inshore areas but was controlled using biological methods.
Pollution of African lakes is increasing becoming a problem. Organic and inorganic pollutants that are dangerous to aquatic ecosystem and human health have been observed in African lakes. including persistent organic pollutants, heavy metals, arsenic, especially in areas adjacent to urban areas around the lake.
Basin factors
The changes in the lake are linked to human activities in its basin.
The main economic activity in the lake basin is agriculture upon which 60-70% of the people depend for their livelihood.
Much of the land in the basin has been converted to agriculture. There is rampant deforestation, wetland degradation and in many places cultivation up to the edge of the lake. This expose the soil, enhances soil erosion which leads to siltation and entry of land based contaminants into the lake.
There are five hydropower dams along the Nile between Lake Victoria and Albert in Uganda and one dam on Sondu Miriu river in Kenya. These dams affect biodiversity and migration of riverine species. Regulation water flow in dams will affect Lake Albert whose water balance depend on Nile inflow.
The Lake Victoria basin has the largest number of urban centers among all African lakes. There are at least seven large towns/cities (Entebbe, Kampala, Jinja, Kisumu, Musoma, Mwanza, Bukoba) along the shores of the lake and nine (Masaka, Mbarara, Busia, Kitale, Eldoret, Kakamega, Kisii, Geita, Biharamuro) in the Lake Victoria basin. Most of these cities and towns have poor sanitation facilities and discharge organic, inorganic and plastic wastes which contaminates the lake.
The lake has major ports and navigation routes connecting Uganda, Kenya and Tanzania.
There is mining and processing of minerals in the basin such as gold and copper which pollute the lake with chemicals such as mercury. Sand mining is increasing and poses another threat to the lake.
The lake and basin are home to other wildlife including birds, crocodiles, and Hippos.
Governance
Programs
Programs have been implemented on Lake Victoria and its basin to address the factors that have influenced the health and productivity of the lake over different periods.
There are national research and academic institutions that have implemented projects on a continuous basis to generate information and data for management of the lake and its basin in collaboration with international scientists.
There are, however some specific efforts that have been made to address urgent issues.
Establishing the source of the Nile by John Speke in 1862 is one of the first recorded expeditions to Lake Victoria to bring it to the attention of the international community although local communities were aware of the lake and implemented management measures.
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The first detailed survey of Lake Victoria by Graham in 1928 arose out the concern that the native tilapias were being ever exploited. It provided basic information on the lake, set mesh size limits for exploitation of the native tilapia fishery, and proposed setting up of research and governance systems that were set up on the lake.
The UNDP/FAO Lake Victoria Fisheries Research Project (LVFRP) of 1969 to 1971 estimated the fish stocks of the lake and evaluated the use of trawling in exploitation of haplochromines that were abundant in the lake.
Three phases of The Lake Victoria Fisheries Research Project supported by the European Union developed management plans following emergence of the Nile perch fishery and set up a slot size for harvesting Nile perch.
Many other projects supported by development partners and collaborators have provided information on fisheries, environment and socio-economics of Lake Victoria.
The Lake Victoria Environment Program(s) supported by the World Bank was a multi-sector project to guide environmental management of Lake Victoria and its basin.
There have been projects to improve management and utilization of small pelagic fishes supported by FAO, EU and IDRC.
There is therefore a lot of information on the lake but it needs to be properly synthesized to guide management measures.
Policies
The programs that have been implemented on the lake have guided policies to address issues that have affected the health and productivity of the lake.
The information generated by research, and collaborators has guided development of policies management of the lake but there have also been targeted interventions.
The first targeted intervention was survey of the whole lake by Graham in 1928 which set mesh size limits to regulate exploitation the native tilapia fishery and proposed establishment of research and governance systems that were set up on the lake.
The UNDP/FAO Lake Victoria Fisheries Research Project (LVFRP) provided guidance on the available fish stocks, use of trawling in exploitation of haplochromines.
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The EU Lake Victoria Fisheries Research Projects developed a fisheries management plan and set up a slot size for harvesting Nile perch.
There have been many other projects supported by development partners that have provided information on fisheries, environment and socio-economics of Lake Victoria.
The Lake Victoria Environment Program(s) provided information on how the different factors can be managed to promote sustainable use of the lake.
There have been projects to improve management and utilization emerging fisheries especially of small pelagic fishes supported by FAO, EU and IDRC.
Institutions
Policies for management of the lakes are implemented at national level.
All countries have national sectoral institutions to generate information and implement management measures.
The factors influencing sustainable use of the resources of the lake are multi-sectoral and their management and different sectors such as those responsible for environment, water, fisheries, agriculture, forests, dams, urban development, mining, transport, and tourism need to work together for its effective management.
Since Lake Victoria, including its basin is shared by five countries, the policies to be implemented at national level are harmonized between the countries sharing the lake before being translated into policies for implementation at national level.
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The countries sharing the lakes have from historical times had regional mechanisms for harmonization of measures for management of the lake such the Lake Victoria Commission, The CIFA sub-committee for Lake Victoria, The Lake Victoria Basin Commission (LVBC), and the Lake Victoria Fisheries Organization (LVFO).
The lake has also established community Beach Management Units (BMUs) to work with government institutions in management of the resources of the lake.
There have also been national and regional NGOs that have implemented projects in sustainable use of the resources of the lake.
There are, therefore institutions to develop and implement policies in management of the lakes. What is required is for them to be adequately empowered to perform their functions.
Funding
There has been inadequate funding for research and management efforts on the lake.
The countries sharing the lake are exploring sustainable funding through generation funds from the lake but this has so far not been successful but needs to be followed up.
The costs of implementing projects could also be reduced through collaborative effort and sharing of information.
Management information systems
A number of programs have been implemented on the lake and generated information which has been translated into policies for management of the lake but challenges for sustainable use of the lakes still remain.
Much of the information is scattered, inaccessible, sometimes in forms that are not easily applied by end users and remains in forms that are not translated into policy.
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The primary goal of this intervention is to mobilize, package, and make information and data accessible in forms that can be used by a wide range of stakeholders and increase awareness.
Specific efforts are being made to apply digital systems for development using ICT given the increase in mobile applications.
Outreach invests will be organised by partners around the lakes.
Members will meet at least once every three to five years to share available information on different lakes and agree on future plans.
Interventions
Despite the enormous effort in implementation of measure for sustainable use of the lake there is still need for a more holistic approach to enable the lake provide the multiple ecosystem and livelihood services.
Measure should be taken to control the rapid human population growth rates to reduce pressure on the resources.
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Access to sanitation facilities especially clean portable water should be improved.
Incidences of water related diseases should be monitored and measures to manage them put in place.
Measures should be taken to conserve fish species diversity through setting up of protected areas, manage and improve stocks of depleted large commercial species..
Fishing capacity (number of fishermen, boats, gear types and sizes) should be regulated.
Emerging fisheries especially that of small pelagic fishes should be developed and species specific management plans prepared.
Cage aquaculture should be practiced using best management practices to reduce impacts on the lake and should be closely monitored.
Alternative livelihood option should be developed specifically for fishers to reduce over dependence on fisheries.
Invasive aquatic weeds should be identified, prevented, monitored, and their spread controlled.
The impacts of climate change on aquatic systems and livelihoods should be investigated, and adaptation and mitigation measures developed and implemented.
Sustainable land use practices should be promoted, deforestation managed, afforestation promoted, and degradation wetlands and vegetation along lake shores and riverbanks enforced.
The impacts of dams on aquatic ecosystems should be monitored and managed.
Urban centers should be planned properly and the impact of urban activities on the lakes identified, monitored and managed.
The impacts of mineral exploration and exploitation should be determined, monitored and managed.
The types and sources of pollutants should be identified and managed.
Programs previously implemented on the lake should be examined to guide addressing current and emerging challenges.
Policies should be developed to address emerging issues and existing ones aligned to address changes in the resources of the lake.
Existing regional efforts for management of the lakes should be consolidated and strengthened.
Research and management institutions should be networked to improve efficiency and reduce transaction costs to mobilize, harmonize, share information, increase awareness and implement management actions.
The development of sustainable funding mechanisms for development and management of the resources of the lake from its own resources should be revisited.
