The Heart of East Africa: Lake Victoria’s Environmental Challenges and Sustainability

Introduction

Lake Victoria is the largest lake in Africa located in Africa’s Great Lakes region in East Africa. It is shared by three countries, Kenya (6%), Tanzania (49%) and Uganda (45%). It is also the largest tropical lake in the world and the second largest fresh water lake in the world after Lake Superior in America. It has a surface area of nearly 59,947 km² , an average depth of 40 meters and a maximum depth of approximately 80 meters. The lake has several local names such as Nam Lolwe in Dholuo, Nyanza in Kinyarwanda, Ukerewe in Kiswahili and Nnalubaale in Luganda. As the name suggests, it was renamed after Queen Victoria by John Hanning Speke who was a British explorer who documented the lake in 1858. Lake Victoria is very important in the ecosystem of the African Great Lakes region because it provides water for its surrounding residents. It also supports the largest inland fishing industry in Africa as it has many species of fish such as lungfish, cichlids, catfish, elephant fish, crabs, tilapia and the Nile perch among others. The lake is also one of the sources of the River Nile meaning that its water is used by people as far as Egypt and Sudan.

According to geologists/hydrologists, the main source of Lake Victoria’s water is direct rainfall (80%). In addition, the lake receives its water from rivers and small streams. The largest river which drains into Lake Victoria is the Kagera River whose origin is in Burundi or Rwanda. The other important rivers which supply the lake are the Migori, Yala, Sio, Sondu Miriu, Mogusi, Nyando rivers from the Kenyan side. From the Tanzanian catchment, the important rivers are the Mori, Mara, Kagera, Mbalageti, Grumeti, Simiyu and Mirongo. The main rivers supplying the lake from the Ugandan side are the Katonga, Sio, Bukora and Kagera. Its only outflow is the Nile River as part of the White Nile river system. However, approximately 80% of the water leaving the lake is lost through evaporation.

2. Socio-economic Setting

Lake Victoria is critically important because it supports over 42 million who rely on it as their source of drinking water, transport, food as well as employment. The lake produces over a 300,000 tonnes of fish per year although its rapidly growing population has led to a substantial reduction of the catch rate per capita over the past few years. Like other lakes around the world, Lake Victoria and its catchment areas have been negatively affected by a wide range of human activities. These include oil spills, climate change, proliferation of introduced invasive species, overfishing, the discharge of untreated waste, deforestation of the riparian areas and the over-abstraction of water.The purpose of this article is explain the environmental challenges faced in the lake’s ecosystem as well as ways of ensuring that the lake is used in a sustainable way in the future. This is particularly important because over 70% of the people in the lake’s riparian/catchment areas rely on agricultural production of crops such as bananas, maize, livestock and coffee among others as their primary source of livelihood. Moreover, the water originating from the lake is important in generating electricity through hydroelectric power plants on the Nile river. As such, the preservation of the lake is important for the survival and prosperity of the population in the region.

3. Environmental Challenges

3.1 Decline in Water  Quality

According to observers and environmental experts, the Lake Victoria ecosystem has gone through alarming changes over the last thirty years. For example, the lake has witnessed the development of large algae blooms, particularly the toxic blue green variety. The transparency of the lake’s water has also declined to one meter or less for a majority of the year from five meters in the 1930s. In addition, the growth of water hyacinth in the lake has been rapid even though it was completely absent from as late as 1989. Water hyacinth is harmful because it chokes waterways/landings and harms biodiversity in the lake. The reduction of oxygen at lower lake depths, overfishing and introduced fish species threaten biodiversity and artisanal fishing. These changes are attributed to eutrophication due to the increase of nutrient input in the lake and the introduction of the nile perch which negatively affected the food web structure.

The pollution of the lake’s water from organics and heavy metals is mostly localized. For instance, zinc, copper, chromium and lead can be found in the Mwanza Gulf’s sediments in concentrations which are not dangerous. It is not surprising that such concentrations are found in areas near urban centers indicating their industrial sources. The shores of Lake Victoria are attractive to industries due to the availability of water which is used in a variety of industrial processes, cheap transport through the lake and the abundance of cheap labor. Some of the heavy metals also originate from industrial discharge into the rivers which load into the lake. In addition, oil spills can also be a key cause of water pollution and decline of water quality in Lake Victoria because it used in the transport of oil products by the riparian countries.

3.2 Increased Land Use

The increased use of land and the growth of livestock/human population around the lake have led to a rapid increase in pollution from farms, industries and municipalities. For example, industrial discharge can be seen in some of the rivers  and in cities/towns along the shoreline such as Mwanza, Kisumu and Kampala. The sources of pollution to the lake includes basic industries such as fish processing, breweries, tanneries, abattoirs and agroprocessing among others. Moreover, the growth of small-scale gold mining in some parts of Tanzania leads to the discharge of mercury into the lake especially when the mining waste is not contained. The nutrient flow into Lake Victoria mainly originates from the burning of wood-fuels, human/animal waste from neighboring areas and eroded sediment in the riparian areas. The nutrient discharge into the lake makes the management of eutrophication in the lake very difficult.

The cultivation of annual crops such as maize, beans and potatoes among others is one of the main causes of soil erosion into the lake. The forest areas around the lake have been cleared for agriculture and settlement. Such poor land management practices also lead to severe erosion of the soil. According to experts, the use of land leads to eutrophication because it has an major impact on the nutrients absorbed into the lake. The overgrazing by over a million goats and 1.5 million cattle also poses a major challenge because it exceeds the sustainable grazing rate by a factor of at least 5. It is well known that overgrazing is a major cause of soil erosion which leads to siltation and and the growth of weeds in the lake.

3.3 Aquatic Weeds

The spread of water hyacinth in Lake Victoria is one of the main challenges facing its ecosystem. Water hyacinth is an invasive aquatic macrophyte which was reported in the lake in 1989 for the first time. It allegedly entered the lake via River Kagera in the Ugandan section and spread to other regions including Kenya and Tanzania. According to the Ugandan Water Hyacinth Management Association, over 1.25 million tonnes of water hyacinth occurs in the lake annually while an another 13t enter from the Kagera river per week. The fact that water hyacinth has a very high growth rate means that it quickly causes harm by blocking waterways, water abstraction units as well as hydropower plants among others. It also blocks fish landing beaches and piers thus preventing boats from docking. In fact, the weed has already lead to the closure of some fish landing beaches in Kenya and Uganda.

The decomposition of weeds is also a threat because it leads to the deoxygenation of water and causes the loss of biodiversity in the lake due to the decline of water quality. As such, water hyacinth is one of the greatest threats to threatened fish species in Lake Victoria such as the cichlids. The weed can also harbor venomous snakes which pose a threat to local communities. Additionally, it provides the ideal habitat for disease vectors for diseases such as filariasis, malaria and encephalitis. It also adversely affects recreation activities on the shores of lake and reduces the possibilities of bathing/washing for the local population.

Water hyacinth produces large numbers of long-lived seeds which can survive for nearly 30 years as well as weed populations that can double every five to fifteen days at temperatures ranging from 25-27.5°C. It forms a permanent floating fringe that often replaces other aquatic plants such as the obligate acropleustophyte, pistia stratiotes, at the lake’s open water interface/wetland. It is estimated that at its peak, water hyacinth covered over 18,000 hectares leading to serious damage on the livelihoods of the farming communities and local fishermen.Although there are no authoritative estimates of the negative effects of the spread of water hyacinth, it is well known that the weed causes a dramatic decline in the fish catch for the fishermen.

The authorities in Kenya, Tanzania and Uganda have taken measures that have lead to a significant reduction in the area affected by the water hyacinth infestation but so far, they have not succeed in completely eliminating it. This is because it produces large quantities of seeds which allow it to regrow after being uprooted. A combination of biological as well as physical methods are used to fight the spread of the weed. Biological control through the use of two weevil species (Neochetina bruchi and neochetina eichhomia) has proven to be very successful.  The success of biological control methods was possible because of the involvement of local fishing communities in the distribution and rearing of the weevils. Physical removal of the weed mostly involves large harvesting and the use of chopping boats.

3.4 Reduction in Biodiversity

Originally, Lake Victoria had a variety of species of fish with two tilapine species (O. Variabilis and Oreochromis Esculentus) being the most important. In early 1950s, it had a diverse fish fauna, made up of 28 genera and approximately 350 species. Over 300 of these species were haplochromine cichlids. In the 1950s, non indigenous tilapiines, Nile tilapia and Nile perch were introduced into the lake. The tilapiines were introduced to increase the declining stocks of  the indigenous O. esculentus and O. variabilis and to reduce the population of haplochromines which were considered to be ‘trash fish’ that had little value. The haplochromines were the most populous species of fish in the 1970s making up nearly 80% of the fish stocks. In the same decade, the population of the Nile perch increased rapidly accompanied by the decline and even disappearance of some native species. It is estimated that in the last 50 years, approximately 200 species of fish in the lake have disappeared entirely after being eaten by the Nile perch. Some of these species may also have disappeared due to the rapid eutrophication of the lake.

The Nile tilapia and Nile perch have had both negative and positive impacts on the fisheries in Lake Victoria. The positive contributions include the increase in export earnings, increased employment opportunities, increased income for the fishermen and increased supply of delicious protein. The fact that the Nile perch is so important to the economy of the riparian nations means that the pressure on the indigenous species will not reduce in the future. As a result, more and more indigenous species of fish will continue to disappear due to the predatory nature of the introduced species.

3.5 Overfishing

Lake Victoria is an important source of income for millions fishermen in Kenya, Tanzania and Uganda. Fishing is particularly important because of the high poverty rates which forces people to engage in artisanal small-scale fishing. The high number of fishermen and illegal fishing operations have led to a significant decline in the fish stocks. It is estimated that the tonnage of undeclared and illegally caught fish is nearly double the declared volume. The decline of fishing stocks affects various species including the lungfish, Nile perch and Nile tilapia. In spite of the measures taken by the authorities to clamp down illegal fishing, the stock of the Nile perch has declined by at least 75%. The average weight of caught perch has also reduced to less than 10 kilograms from 50kg in the 1980s. For instance, a Regional Office in Mwanza complained that Nile Perch below 50 centimeters are now sold everywhere in the markets.

According to experts, overfishing is expected to continue growing due to the rapid growth of the youthful population in the three countries. It is estimated that every year, over 1000 fishing boats are launched into the lake thus increasing the pressure on the fishing stock annually. The decline in the fishing stock also leads to the rise in prices of the Nile perch and tilapia meaning that the industry is becoming more lucrative to criminals and illegal fishermen across the region. Unfortunately, illegal fishing is also enabled by the high rates of corruption in the region where law enforcement officers receive significant bribes to enable the criminals who defy the fishing laws escape accountability. In the future, the fish stocks are expected to decline thus posing a serious threat to millions of people who rely on the lake for their livelihood/survival.

4. Sustainability

4.1 Community Involvement

The involvement of communities in the management of the fisheries sector in Lake Victoria is very important in ensuring that the lake’s resources are used in a sustainable manner. As a result organizations such as the Lake Victoria Fisheries Research Project (LVFRP) and the Lake Victoria Environment Management Programme (LVEMP) have beach management units in the three riparian countries to enable local initiatives for the enforcement of fisheries rules to prevent overfishing. In addition, each country has its own national laws that govern the fishing sector in the lake. The engagement of fishing communities has been particularly successful in controlling water hyacinth through the rearing and release of weevils. Both activities prove that community engagement is very successful when the outcomes have a direct impact on the livelihood of such communities. Unfortunately, the community engagement has not been successful in reducing the sediment and nutrient loads getting into the lake from inland sources.

The Lake Victoria region has numerous non-governmental organizations (NGOs) such as the East African Communities Organization that are mainly focused on environmental issues and poverty. These organizations are important in providing education to the population on how to ensure sustainability in the exploitation of the lake’s resources including water and fish. In future, it will be necessary to diversify the economy to lift people out of poverty and reduce the pressure on Lake Victoria as the primary source of livelihood for the population. In addition, fish farms in the lake could also prove to be effective in meeting the demand for fish thus reducing the need for overfishing.

4.2 Institutional Roles and Regional Cooperation

The fact that Lake Victoria is shared by the three riparian countries makes it obvious that regional cooperation is essential in managing the lake’s resources. However, Kenya, Uganda and Tanzania currently do not have an agreed policy for the management of the lake. Instead, that role is assigned to the East African Community but the coordination among the countries remains limited. The fact that most of the activities in the lake are nationally managed and regulated means that there is a lack of transnational water discharge/quality standards and management protocols. In spite of the absence of cooperation on these issues, the three countries were able to cooperate in the management of water hyacinth which posed a serious threat to their export earnings from the lake’s fisheries. The LVEMP played a prominent role in this effort.

It is well known that a lot of the pollutants entering the lake come from its catchment. However, the management of the catchment areas is managed separately by the respective national governments with little or no cooperation. As such, it is almost impossible to jointly monitor the discharges into the lake. In future, it will be necessary to create joint agricultural/industrial standards to manage the discharge of pollutants into the lake. The national governments and organizations such as the World Bank and the African Development Banks can be important in providing financial aid to finance regional organizations such as the Nile Basin Initiative (NBI), the  Lake Victoria Fisheries Organization (LVFO) and LVEMP which play key roles in the management of the lake.

4.3 Research and Technical Capacities/Cooperation

The three countries have good scientific and technical capacities for the management of fisheries including fisheries research institutions with well trained workers, boats and analytic capabilities. These institutions are not only important in fisheries research but also water quality research. The three countries also have laboratory capacities for controlling the quality of fish exports to international markets such as the European Union. The existence of these technical capacities has proven to be important in ensuring the sustainability of the lake’s resources. However, the infrastructure required in the water quality and fisheries research is costly meaning that external investment from the governments and other actors is necessary. Some research organizations are also doing important work by introducing millions of fingerlings into the lake to reduce the decline of fish stock in the lake thus ensuring the sustainability of its fisheries.

Catchment management remains one of the weaknesses in managing the resources in the Lake Victoria basin mostly because the technical capacity is not as developed as in fisheries research. The Universities in the region can provide this capacity but at the moment, the governments have not invested the necessary resources needed to facilitate effective catchment management. As such, challenges such as the over-exploitation of riparian land continues unabated. The discharge of waste into the lake is also not regulated meaning that the pollution of the lake increases every year. In future, it is necessary for the governments to ensure that the industries surrounding the lake adhere to environmental standards to avoid the over-pollution of the lake’s water. In addition, farmers near the lake should be educated on the proper use of agricultural chemicals to control the discharge of nutrients into the lake.

References

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