Lake Victoria
Overview
 
Lake Victoria is one of the African Great Lakes
African Great Lakes
The African Great Lakes are a series of lakes and the Rift Valley lakes in and around the geographic Great Rift Valley formed by the action of the tectonic East African Rift on the continent of Africa...

. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke
John Hanning Speke
John Hanning Speke was an officer in the British Indian Army who made three exploratory expeditions to Africa and who is most associated with the search for the source of the Nile.-Life:...

, the first European to discover this lake.

With a surface area of 68800 square kilometres (26,563.8 sq mi), Lake Victoria is Africa’s largest lake by area, and it is the largest tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

 lake in the world. Lake Victoria is the world's second largest freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 lake by surface area (only Lake Superior
Lake Superior
Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...

 in North America is larger).
Encyclopedia
Lake Victoria is one of the African Great Lakes
African Great Lakes
The African Great Lakes are a series of lakes and the Rift Valley lakes in and around the geographic Great Rift Valley formed by the action of the tectonic East African Rift on the continent of Africa...

. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke
John Hanning Speke
John Hanning Speke was an officer in the British Indian Army who made three exploratory expeditions to Africa and who is most associated with the search for the source of the Nile.-Life:...

, the first European to discover this lake.

With a surface area of 68800 square kilometres (26,563.8 sq mi), Lake Victoria is Africa’s largest lake by area, and it is the largest tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

 lake in the world. Lake Victoria is the world's second largest freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 lake by surface area (only Lake Superior
Lake Superior
Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...

 in North America is larger). In terms of its volume, Lake Victoria is the world's eighth largest continental lake, and it contains about 2,750 cubic kilometers (2.2 billion acre-feet) of water.

Lake Victoria receives most of its water from direct precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

 or from thousands of small stream
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

s. The largest stream flowing into this lake is the Kagera River
Kagera River
The Kagera River, also Akagera River, is an East African river, forming part of the upper headwaters of the Nile and carrying water from its most distant source....

, the mouth
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

 of which lies on the lake's western shore. There are two rivers that leave the lake, the White Nile
White Nile
The White Nile is a river of Africa, one of the two main tributaries of the Nile from Egypt, the other being the Blue Nile. In the strict meaning, "White Nile" refers to the river formed at Lake No at the confluence of the Bahr al Jabal and Bahr el Ghazal rivers...

 (known as the "Victoria Nile" as it leaves the lake), flows out at Jinja, Uganda
Jinja, Uganda
Jinja is the largest town in Uganda, Africa. It is the second busiest commercial center in the country, after Kampala, Uganda's capital and only city. Jinja was established in 1907.-Location:...

 on the lake's north shore and the Katonga River
Katonga River
The Katonga River is a river in Uganda, in East Africa.-Location:River Katonga is located in the southwestern part of Uganda. It starts from Lake Victoria and flows, first, northwards into Lake Wamala...

 flows out at Lukaya
Lukaya
Lukaya is a town in Kalungu District, in Central Uganda. It is one of the municipalities in Kalungu District.-Location:Lukaya lies on the Masaka-Kampala Highway, close to the shores of Lake Victoria and just south of the Equator. The town is approximately , by road, northeast of Masaka, the largest...

 on the western shore connecting the lake to Lake George
Lake George (Uganda)
Lake George or Lake Dweru is a lake in Uganda. It covers a total surface area of 250 km² and is a part of Africa's Great Lakes system but is not itself considered one of the Great Lakes. Like the other lakes in the region it was named after a member of the British royal family, in this case...

.

Lake Victoria occupies a shallow depression in Africa and has a maximum depth of 84 metres (275.6 ft) and an average depth of 40 metres (131.2 ft). Its catchment area
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 covers 184,000 square kilometers (71,040 sq mi). The lake has a shoreline of 4828 kilometres (3,000 mi), with islands constituting 3.7% of this length, and is divided among three countries: Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

 (6% or 4100 km² (1,583 sq mi)), Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

 (45% or 31000 km² (11,969.2 sq mi)) and Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

 (49% or 33700 km² (13,011.6 sq mi)).

Lake Victoria supports Africa's largest inland fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...

.

Biology and ecology

Before 1954, Lake Victoria's ecology was characterised by enormous biodiversity. It was inhabited by over 500 species of fish, 90% of which were cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...

s belonging to the genus Haplochromis
Haplochromis
Haplochromis is a ray-finned fish genus in the family Cichlidae. It has been used as the default "wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus"...

. They are thought to have evolved in Lake Victoria within the last 12,000 years. They are known for their extraordinary ability to evolve rapidly to suit extremely localised and diverse environments, a characteristic termed 'evolutionary plasticity'. This ability has made the cichlid species of Lake Victoria an extremely successful fish. Haplochromis species accounted for some 80% of the fish biomass of the lake, an abundance which led Graham to believe that this species flock could support a trawler fishery of up to 200 boats. It also meant that Lake Victoria at one time boasted one of the most diverse fish environments on earth. With such diversity, the cichlids of Lake Victoria managed to exploit virtually every food source available, including most detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...

, zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

 and phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

.

Haplochromis species are small and bony, and were generally not favoured in catches. Riparian populations preferred the lake's two endemic species of tilapia
Tilapia
Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...

 (Oreochromis esculentus and O. variabilis). Hence, by the late 1940s, British colonial authorities were debating the overall ecological efficiency
Ecological efficiency
Ecological efficiency describes the efficiency with which energy is transferred from one trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an ecosystem....

 of the lake. For many authorities at this time, the lake needed a large and efficient predator to turn Haplochromis fish stocks into something more economically valuable. The prime candidate was the Nile perch
Nile perch
The Nile perch is a species of freshwaterfish in family Latidae of order Perciformes. It is widespread throughout muchof the Afrotropic ecozone, being native to the Congo, Nile, Senegal, Niger, and Lake Chad, Volta, Lake Turkana and other river basins. It also occurs in the brackish waters of...

 (Lates niloticus). Arguments in favour of introducing a predator was as follows:
  1. Evidence from other African lakes suggested that the Nile perch could do well commercially, and if the fish were introduced into Lake Victoria, it would no doubt eat the Haplochromis, and hence improve the overall value of the fishery. In addition, it was suggested that by introducing such a fish, fishers might turn their attentions to catching it, so easing some of the pressure on tilapia stocks. Because the Nile perch can weigh as much as 200 kilograms (440.9 lb), it was argued, fishers would be encouraged to use large mesh-sizes to capture it. Furthermore, the perch was said to prefer off-shore habitats, and this would serve to relieve pressure on the in-shore tilapia fishery.
  2. In those lakes where the Nile perch was a native it co-existed with tilapia species, and therefore it posed no great danger to commercially important tilapia stocks in Lake Victoria.
  3. The potential size of the perch made it a fine sports fish, and this might attract sports fishers and tourists to the lake region.
  4. Finally, archaeological findings close to Lake Victoria suggested that an ancestor of the Nile perch had been native to the Miocene
    Miocene
    The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

     predecessor of Lake Victoria, Lake Karunga. It was reasoned, then, that if the perch had once been native to the lake, there was little reason why it could not be a native again.


The arguments against its introduction were as follows:
  1. Predators can never be as abundant as non-predators because of their nutritional requirements. In other words, the amount of fish a Nile perch has to eat to produce a kilogram of flesh is far greater than the amount of vegetative matter a tilapia has to eat to produce an equal amount of flesh. In ecological terms, the Nile perch is inefficient. As mentioned above, the fertility of tropical waters depends on the rate at which nutrients (mainly detritus) are brought back into solution. The Nile perch, however, does not eat this detritus, and it was argued that its introduction would do little to improve the over-all ecological efficiency of the lake. If any fish should be introduced, it should be a herbivore or a detrivore.
  2. It would be wishful thinking to suppose that the Nile perch would exclusively consume haplochromines.
  3. Given the complexity of tropical ecosystems, it is impossible to predict what might happen should the Nile perch be introduced.


While the argument continued, it was agreed that tilapia stocks needed bolstering largely as a result of increasing fishing pressure on indigenous species, associated with the expansion of the market for fresh fish in the 1940s. Tilapia introductions started in the early 1950s with Oreochromis leucostictus
Oreochromis leucostictus
Oreochromis leucostictus is a species of fish in the Cichlidae family. It is found in Burundi, the Democratic Republic of the Congo, Kenya, Tanzania, and Uganda...

from Entebbe, and followed by Tilapia zillii (Winam Gulf, 1953), T. rendalli (Winam Gulf 1953/54), O. niloticus
Oreochromis niloticus
The Nile Tilapia, Oreochromis niloticus is a relatively large cichlid fish, which is native to Africa from Egypt south to East and Central Africa, and as far west as Gambia. It is also native to Israel, and numerous introduced populations exist outside its natural range.It is also commercially...

(Kagera River 1954) and O. mossambicus
Oreochromis mossambicus
The Mozambique tilapia, Oreochromis mossambicus, is a tilapiine cichlid fish native to southern Africa. It is a popular fish for aquaculture...

(Entebbe 1961/62). Because tilapia are detrivores and herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

s, these introductions were regarded as less threatening than the introduction of any carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

. Nevertheless, while the argument over the introduction of the Nile perch raged throughout the early 1960s, it seems that it had already been surreptitiously introduced in 1954 from Uganda. Once it had been discovered to be in the lake, further official introductions occurred in 1962 and 1963.

Introduced tilapia species were unable to establish themselves in the lake between the 1950s and 1963. Following unusually heavy rainfall in the early 1960s, however (the so-called 'Uhuru Rains'), the lake-level rose considerably, flooding large areas of shore-line, and opening up new breeding areas to fledgling tilapia stocks, so creating the opportunities for these exotic species to compete with indigenous stocks. Of the six exotic species introduced, two – Oreochromis niloticus and O. zillii – were to firmly establish themselves in the lake, so that by the early 1980s, these two species comprised the mainstay of tilapia catches. Of the indigenous species, O. esculentus was extirpated from the lake as a consequence of competition with introduced tilapiids, while O. variabilis populations declined significantly.

The Nile perch is a substantial predator. One specimen, preserved at the Kisumu
Kisumu
Kisumu is a port city in western Kenya at , with a population of 355,024 . It is the third largest city in Kenya, the principal city of western Kenya, the immediate former capital of Nyanza Province and the headquarters of Kisumu County. It has a municipal charter but no city charter...

 Museum in Kenya, weighed 184 kg (405.7 lb) when landed. Populations of the fish established themselves in a clockwise motion around the lake, starting in Uganda, followed by Kenya and ending in Tanzania. Initial catches were minimal, but grew rapidly in the 1980s, heralding the start of the so-called 'Nile perch boom'. "On the face of it...the lake after the debut of Lates [Nile perch] has turned into a fish producer that can only be described in Gargantuan terms".

The introduction of the Nile perch had a decisive impact on Haplochromis stocks which it favoured as its prey, affecting both their abundance and diversity. It is believed that the contribution of this species flock to the fish biomass of the lake has decreased from 80% to less than 1% since the introduction of the Nile perch, and that some 65% of the Haplochromis species were driven to extinction in the process, an event which may well represent the largest extinction event
Extinction event
An extinction event is a sharp decrease in the diversity and abundance of macroscopic life. They occur when the rate of extinction increases with respect to the rate of speciation...

 amongst vertebrates in the 20th century.

Freed from their evolutionary predators, populations of the diminutive endemic silver cyprinid
Silver Cyprinid
The silver cyprinid, Rastrineobola argentea, is a species of ray-finned fish in the family Cyprinidae, the only member of the genus Rastrineobola. It is found in the Lake Victoria of Kenya, Tanzania, and Uganda...

 Rastrineobola argentea ( in Luo, in Ganda and in Swahili
Swahili language
Swahili or Kiswahili is a Bantu language spoken by various ethnic groups that inhabit several large stretches of the Mozambique Channel coastline from northern Kenya to northern Mozambique, including the Comoro Islands. It is also spoken by ethnic minority groups in Somalia...

), flourished, developing into huge shoals. In turn, Pied Kingfisher
Pied Kingfisher
The Pied Kingfisher is a water kingfisher and is found widely distributed across Africa and Asia. Their black and white plumage, crest and the habit of hovering over clear lakes and rivers before diving for fish makes it distinctive. Males have a double band across the breast while females have a...

 (Ceryle rudis) populations, that had hitherto fed on haplochromines, exploded in response to this new food source. Similar and other impacts have propagated throughout the ecosystem.

Given its 'evolutionary plasticity', it follows that Haplochromis should adapt rapidly to the new environmental conditions generated by the Nile perch 'boom' and eutrophic conditions. Evidence from studies on the lake does suggest that this is happening. One haplochromine, H. (Yssichromis) pyrrhocephalus
Haplochromis pyrrhocephalus
Haplochromis pyrrhocephalus is a freshwater fish species in the family Cichlidae. It is endemic to the Tanzanian part of Lake Victoria; as it seems it is extinct in Kenyan waters where it formerly was also found.-Source:...

, a zooplanktivore, was almost driven to extinction by the Nile perch. This species has recovered alongside increased exploitation of the Nile perch, at a time (the 1990s) when water clarity and dissolved oxygen levels had declined as a consequence of eutrophication. Over a period of just two decades, H. pyrrhocephalus responded to raised hypoxia
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...

 (oxygen deficiency) by increasing its gill surface area by 64%. Head length, eye length, and head volume decreased in size, whereas cheek depth increased. The former morphological changes may have occurred to accommodate this increased gill size. Other morphological changes suggest adaptations in response to the availability of larger and tougher prey types.

Fisheries

By the end of the 1940s, fish stocks were under severe pressure. The market for fish grew since railways were available to carry fish to the coast and settlements in between. Improved fishing boats and nets were introduced. British colonial authorities set out to remedy this through the introduction of exotic species, including tilapia
Tilapia
Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...

 and the Nile perch
Nile perch
The Nile perch is a species of freshwaterfish in family Latidae of order Perciformes. It is widespread throughout muchof the Afrotropic ecozone, being native to the Congo, Nile, Senegal, Niger, and Lake Chad, Volta, Lake Turkana and other river basins. It also occurs in the brackish waters of...

. These introductions had five main impacts. The first of these was the rise of the Nile perch. The fish took some time to establish itself, and only began to appear catch statistics in the mid-1970s. By the 1980s, the 'explosion' of this species was being referred to as the Nile perch 'boom'. Catches climbed from about 335 mt in 1975, to a peak of 380,776 mt in 1990. The second impact was the Nile perch's devastation of the Haplochromis
Haplochromis
Haplochromis is a ray-finned fish genus in the family Cichlidae. It has been used as the default "wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus"...

species flock, its main food source. Catches of this species crashed. The third impact related to the lake's diminutive endemic silver cyprinid
Silver Cyprinid
The silver cyprinid, Rastrineobola argentea, is a species of ray-finned fish in the family Cyprinidae, the only member of the genus Rastrineobola. It is found in the Lake Victoria of Kenya, Tanzania, and Uganda...

, the . Freed from competition (with Haplochromis species) for food sources, this species thrived. It was not the main target of the Nile perch, and catches increased spectacularly from 13,000 mt in 1975, to an all time high 567,268 mt in 2006. The fourth main impact of the introductions related to the exotic tilapia species. One of these, the Nile tilapia (Oreochromis niloticus), was to establish itself firmly in the fishery. Tilapia catches from the lake rose from about 13,000 mt in 1975, to an all time high of around 105,000 mt in 2000. There can be little doubt that these introductions saved the fishery from collapse. With such increases, so too the entire production system on the lake changed, the fifth and final key change. Prior to the arrival of the colonial administration, the fishery was dominated by fishermen (mainly, although certain fishing techniques were reserved for women) who owned their labour and their fishing gear. Contributing to the near-collapse of the fishery in the 1940s and 1950s was the reorganisation of the fishery into fleets drawing on hired labour and much improved gear. The Nile perch 'boom' was to accelerate and massively expand this process. It coincided with an emerging European market for high-quality white fish meat, prompting the development of industrial fish processing capacity along the lake’s shores in Kisumu
Kisumu
Kisumu is a port city in western Kenya at , with a population of 355,024 . It is the third largest city in Kenya, the principal city of western Kenya, the immediate former capital of Nyanza Province and the headquarters of Kisumu County. It has a municipal charter but no city charter...

, Musoma
Musoma
Musoma is a city located in northern Tanzania. It is the capital of Mara Region. It has a population of 103,497 . Musoma sits on the eastern edge of Lake Victoria not far from the Kenyan border. There are boats that take you across Lake Victoria from Musoma.- Geography :The town is sited in a...

, Mwanza
Mwanza
Mwanza is a mid-sized port city on the southern shores of Lake Victoria in northwestern Tanzania. With an urban population of 1.2 million and a metropolitan population of 2 million, it is Tanzania's second largest city, following Dar es Salaam and ahead of other major Tanzanian cities of Arusha,...

, Entebbe
Entebbe
Entebbe is a major town in Central Uganda. Located on a Lake Victoria peninsula, the town was at one time, the seat of government for the Protectorate of Uganda, prior to Independence in 1962...

 and Jinja
Jinja, Uganda
Jinja is the largest town in Uganda, Africa. It is the second busiest commercial center in the country, after Kampala, Uganda's capital and only city. Jinja was established in 1907.-Location:...

. The export of Nile perch has since expanded away from the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 (EU) to the Middle East, the United States and Australia, and now represents large foreign exchange earnings to the lake's riparian states. In Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

, indeed, its export is second only to coffee
Coffee
Coffee is a brewed beverage with a dark,init brooo acidic flavor prepared from the roasted seeds of the coffee plant, colloquially called coffee beans. The beans are found in coffee cherries, which grow on trees cultivated in over 70 countries, primarily in equatorial Latin America, Southeast Asia,...

 in the rankings of export earnings. In 2006, the total value of Nile perch exports from the lake was estimated to be US$ 250 million. The main market for the perch remains the EU, and the industry is, therefore, subject to the worries of EU health and safety inspectors. The EU has frequently closed its doors to the export for reasons ranging from unsatisfactory hygiene at factories to cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

 outbreaks on the lake shores.

With such high demands for Nile perch, the value of the fishery has risen considerably. Labour inflows into the fishery have increased along with growing demand. In 1983, there were an estimated 12,041 boats on the lake. By 2004, there were 51,712, and 153,066 fishermen. The fishery also generates indirect employment for additional multitudes of fish processors, transporters, factory employees and others. All along the lakeshore, 'boom towns' have developed in response to the demands of fishing crews with money to spend from a day's fishing. These towns resemble shanties
Shanty town
A shanty town is a slum settlement of impoverished people who live in improvised dwellings made from scrap materials: often plywood, corrugated metal and sheets of plastic...

, and have little in the way of services. Of the 1,433 landing sites identified in the 2004 frame survey, just 20% had communal lavatory facilities, 4% were served by electricity and 6% were served by a potable water supply.

The Nile perch fishery has proved controversial, not least between conservationists keen to see the preservation of the lake's unique ecology; and others who recognise the fish's importance to regional economies and poverty alleviation. In the 1990s, one group of thinkers argued that the export of this fish represented a net loss of fish proteins to riparian fishing communities, hence explaining high incidences of malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....

 amongst them. 'Empirical evidence ... vividly show that the growing export of the Nile perch and the commercialisation of the are undermining the survival of households'. Malnutrition amongst these communities are indeed high; one study estimates that 40.2% of children in fishing communities are stunted. Rates of childhood malnutrition are, however, lower around the lake than they were in the agricultural hinterland. At fish landing sites, 5.7% of mothers were found to be chronically malnourished. The latter study, however, argues that these malnutrition levels do not arise from the Nile perch export, but rather as a consequence of gender relations, that tilt income distributions in favour of men, while undermining women's economic status. As the children's primary care givers, this economic status translates directly into the malnutrition rates observed. This economic disparity arises for multiple reasons, including the lack of access that women have to the fishery (very few women actually fish, although some do own fishing boats and gear); children force women to be sedentary (staying close to schools, health facilities and/or social networks), and so are unable to take advantage of the opportunities that emerge through migration, and which are available to men. Women, the authors argue, are forced to exploit peripheral economies, such as the small-scale fish trade, where they must compete against (male) buyers and the fish factories. Women, the study claims, often use sex as a means of developing relationships between fishermen, and so securing a steady supply of fish. While women devote all or most of their income to their children, men have different spending priorities, such as investing in their fishing capacity, drinking and prostitution.

The three countries bordering Lake Victoria – Uganda, Kenya and Tanzania – have agreed in principle to the idea of a tax on Nile perch exports, proceeds to be applied to various measures to benefit local communities and sustain the fishery. However, this tax has not been put into force, enforcement of fisheries and environmental laws generally are lax, and the Nile perch fishery remains in essence a mining operation.

The impact of perch fishing on the local economy is the subject of the documentary Darwin's Nightmare
Darwin's Nightmare
Darwin's Nightmare is a 2004 French-Belgian-Austrian documentary film written and directed by Hubert Sauper, dealing with the environmental and social effects of the fishing industry around Lake Victoria in Tanzania. It premiered at the 2004 Venice Film Festival, and was nominated for the 2006...

.

Environmental issues

There are a number of environmental issue
Environmental issue
Environmental issues are negative aspects of human activity on the biophysical environment. Environmentalism, a social and environmental movement that started in the 1960s, addresses environmental issues through advocacy, education and activism.-Types:...

s associated with Lake Victoria.

Fishing

The introduction of exotic fish species such as the Nile perch
Nile perch
The Nile perch is a species of freshwaterfish in family Latidae of order Perciformes. It is widespread throughout muchof the Afrotropic ecozone, being native to the Congo, Nile, Senegal, Niger, and Lake Chad, Volta, Lake Turkana and other river basins. It also occurs in the brackish waters of...

 has altered the freshwater ecosystem of the lake and driven several hundred species of native cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...

s to extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 or near extinction.

Water hyacinth invasion

The water hyacinth Eichhornia crassipes
Eichhornia crassipes
Eichhornia crassipes, commonly known as Common Water Hyacinth, is an aquatic plant native to the Amazon basin, and is often considered a highly problematic invasive species outside its native range.-Ecology:...

, a native of the tropical Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

, was introduced by Belgian
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

 colonists to Rwanda
Rwanda
Rwanda or , officially the Republic of Rwanda , is a country in central and eastern Africa with a population of approximately 11.4 million . Rwanda is located a few degrees south of the Equator, and is bordered by Uganda, Tanzania, Burundi and the Democratic Republic of the Congo...

 to beautify their holdings and then advanced by natural means to Lake Victoria where it was first sighted in 1988. There, without any natural enemies, it became an ecological plague, suffocating the lake, diminishing the fish reservoir, and hurting the local economies. By forming thick mats of vegetation it causes difficulties to transportation, fishing, hydroelectric power generation and drinking water supply. The plant also affects water circulation in the lake making it a breeding ground for malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

-carrying mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

s. By 1995, 90% of the Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

n coastline was covered by the plant. With mechanical and chemical control of the problem seeming unlikely, the mottled water hyacinth weevil Neochetina eichhorniae
Neochetina eichhorniae
The mottled water hyacinth weevil, Neochetina eichhorniae, is a beetle insect that has been introduced as a biological pest control herbivore agent to waterways and lakes in countries worldwide to control the spread of the invasive noxious weed species Eichhornia crassipes - water hyacinth, an...

was bred and released with good results.

In the late 1990s, the surface area covered by water hyacinth reduced dramatically, for unclear reasons. It is probable that the introduced weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...

s did serve their purpose, although El Niño weather in 1997/1998 probably also contributed. It is thought that an improved light climate, an ever increasing supply of nutrients and a potentially unstable weevil population will allow a resurgence of this plant.

Satellite photos from 2006 show that the water hyacinth has re-invaded the lake. The images show that the Kenyan side of the lake around the Gulf of Winam, Kisumu Bay, and Nyakach Bay are covered by the plant. The new proliferation is attributed to the heavy rains that the region experienced in 2006. These rains brought in nutrients that fed the water hyacinth. Ground photos by NASA confirmed the presence of water hyacinth in Kisumu Bay.

Pollution

Pollution of Lake Victoria is mainly due to discharge of raw sewage into the lake, dumping of domestic and industrial waste, and fertiliser and chemicals from farms. Raw sewage decomposes
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 more cleanly in soil, and should be directed back to the ground rather into a drinking water source.

The Lake Victoria basin is one of the most densely populated rural areas in the world. Its shores are dotted with cities and towns, including Kisumu
Kisumu
Kisumu is a port city in western Kenya at , with a population of 355,024 . It is the third largest city in Kenya, the principal city of western Kenya, the immediate former capital of Nyanza Province and the headquarters of Kisumu County. It has a municipal charter but no city charter...

, Kisii
Kisii, Kenya
Kisii town, located south-western Kenya, is the main urban and commercial centre in Gusii Highlands. A vibrant town, the Kisii municipality has a population of about 83,000, according to 2008 estimates. However, it has a large dependent metropolitan population of over 100,000 residents, as per the...

, and Homa Bay
Homa Bay
Homa Bay is a bay and town on the south shore of Winam Gulf of Lake Victoria, in western Kenya. It lies near Mount Homa and Ruma National Park, the latter noted for Jackson's hartebeests and roan antelope .Homa Bay was once the District...

 in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

; Kampala
Kampala
Kampala is the largest city and capital of Uganda. The city is divided into five boroughs that oversee local planning: Kampala Central Division, Kawempe Division, Makindye Division, Nakawa Division and Lubaga Division. The city is coterminous with Kampala District.-History: of Buganda, had chosen...

, Jinja
Jinja, Uganda
Jinja is the largest town in Uganda, Africa. It is the second busiest commercial center in the country, after Kampala, Uganda's capital and only city. Jinja was established in 1907.-Location:...

, and Entebbe
Entebbe
Entebbe is a major town in Central Uganda. Located on a Lake Victoria peninsula, the town was at one time, the seat of government for the Protectorate of Uganda, prior to Independence in 1962...

 in Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

; and Bukoba, Mwanza
Mwanza
Mwanza is a mid-sized port city on the southern shores of Lake Victoria in northwestern Tanzania. With an urban population of 1.2 million and a metropolitan population of 2 million, it is Tanzania's second largest city, following Dar es Salaam and ahead of other major Tanzanian cities of Arusha,...

 and Msoma in Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

. These cities and towns also are home to many factories that discharge their waste directly into the lake and its influent rivers. These urban areas also discharge raw sewage into the river increasing its eutrophication
Eutrophication
Eutrophication or more precisely hypertrophication, is the movement of a body of water′s trophic status in the direction of increasing plant biomass, by the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system...

 that in turn is helping to sustain the invasive water hyacinth.

Exploration history

The first recorded information about Lake Victoria comes from Arab
Arab
Arab people, also known as Arabs , are a panethnicity primarily living in the Arab world, which is located in Western Asia and North Africa. They are identified as such on one or more of genealogical, linguistic, or cultural grounds, with tribal affiliations, and intra-tribal relationships playing...

 traders plying the inland routes in search of gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

, ivory
Ivory
Ivory is a term for dentine, which constitutes the bulk of the teeth and tusks of animals, when used as a material for art or manufacturing. Ivory has been important since ancient times for making a range of items, from ivory carvings to false teeth, fans, dominoes, joint tubes, piano keys and...

, other precious commodities and slaves. An excellent map
Map
A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes....

, known as the Al Idrisi
Muhammad al-Idrisi
Abu Abd Allah Muhammad al-Idrisi al-Qurtubi al-Hasani al-Sabti or simply Al Idrisi was a Moroccan Muslim geographer, cartographer, Egyptologist and traveller who lived in Sicily, at the court of King Roger II. Muhammed al-Idrisi was born in Ceuta then belonging to the Almoravid Empire and died in...

 map from the calligrapher who developed it and dated from the 1160s, clearly depicts an accurate representation of Lake Victoria, and attributes it as the source of the Nile.
The lake was first sighted by a European
European ethnic groups
The ethnic groups in Europe are the various ethnic groups that reside in the nations of Europe. European ethnology is the field of anthropology focusing on Europe....

 in 1858 when the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 explorer John Hanning Speke
John Hanning Speke
John Hanning Speke was an officer in the British Indian Army who made three exploratory expeditions to Africa and who is most associated with the search for the source of the Nile.-Life:...

 reached its southern shore while on his journey with Richard Francis Burton
Richard Francis Burton
Captain Sir Richard Francis Burton KCMG FRGS was a British geographer, explorer, translator, writer, soldier, orientalist, cartographer, ethnologist, spy, linguist, poet, fencer and diplomat. He was known for his travels and explorations within Asia, Africa and the Americas as well as his...

 to explore central Africa and locate the Great Lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after Queen Victoria
Victoria of the United Kingdom
Victoria was the monarch of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death. From 1 May 1876, she used the additional title of Empress of India....

. Burton, who had been recovering from illness at the time and resting further south on the shores of Lake Tanganyika
Lake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...

, was outraged that Speke claimed to have proved his discovery to have been the true source of the Nile
Nile
The Nile is a major north-flowing river in North Africa, generally regarded as the longest river in the world. It is long. It runs through the ten countries of Sudan, South Sudan, Burundi, Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia, Uganda and Egypt.The Nile has two major...

, which Burton regarded as still unsettled. A very public quarrel ensued, which not only sparked a great deal of intense debate within the scientific community of the day, but much interest by other explorers keen to either confirm or refute Speke's discovery.

The famous British explorer and missionary
Missionary
A missionary is a member of a religious group sent into an area to do evangelism or ministries of service, such as education, literacy, social justice, health care and economic development. The word "mission" originates from 1598 when the Jesuits sent members abroad, derived from the Latin...

 David Livingstone
David Livingstone
David Livingstone was a Scottish Congregationalist pioneer medical missionary with the London Missionary Society and an explorer in Africa. His meeting with H. M. Stanley gave rise to the popular quotation, "Dr...

 failed in his attempt to verify Speke's discovery, instead pushing too far west and entering the River Congo system instead. It was ultimately the Welsh-American explorer Henry Morton Stanley
Henry Morton Stanley
Sir Henry Morton Stanley, GCB, born John Rowlands , was a Welsh journalist and explorer famous for his exploration of Africa and his search for David Livingstone. Upon finding Livingstone, Stanley allegedly uttered the now-famous greeting, "Dr...

, on an expedition funded by the New York Herald
New York Herald
The New York Herald was a large distribution newspaper based in New York City that existed between May 6, 1835, and 1924.-History:The first issue of the paper was published by James Gordon Bennett, Sr., on May 6, 1835. By 1845 it was the most popular and profitable daily newspaper in the UnitedStates...

 newspaper, who confirmed the truth of Speke's discovery, circumnavigating the lake and reporting the great outflow at Ripon Falls on the lake's northern shore.

Nalubaale Dam

The only outflow for Lake Victoria is at Jinja, Uganda
Jinja, Uganda
Jinja is the largest town in Uganda, Africa. It is the second busiest commercial center in the country, after Kampala, Uganda's capital and only city. Jinja was established in 1907.-Location:...

, where it forms the White Nile
White Nile
The White Nile is a river of Africa, one of the two main tributaries of the Nile from Egypt, the other being the Blue Nile. In the strict meaning, "White Nile" refers to the river formed at Lake No at the confluence of the Bahr al Jabal and Bahr el Ghazal rivers...

. The water 12,000 years ago drained over a natural rock weir. In 1952, British colonial engineers blasted out the weir and reservoir. A standard for mimicking the old rate of outflow called the "agreed curve" was established, setting the maximum flow rate at 300 to 1,700 cubic metres per second (392–2,224 cu yd
Cubic yard
A cubic yard is an Imperial / U.S. customary unit of volume, used in the United States, Canada, and the UK. It is defined as the volume of a cube with sides of 1 yard in length.-Symbols:...

/sec) depending on the lake's water level.

In 2002, Uganda completed a second hydroelectric complex in the area, the Kiira Power Station
Kiira Power Station
Kiira Power Station, sometimes spelled Kiyira Power Station, is a hydroelectric power station with an installed capacity of 200MW, in Uganda.-Location:...

, with World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...

 assistance. By 2006 the water levels in Lake Victoria had reached an 80-year low, and Daniel Kull, an independent hydrologist living in Nairobi
Nairobi
Nairobi is the capital and largest city of Kenya. The city and its surrounding area also forms the Nairobi County. The name "Nairobi" comes from the Maasai phrase Enkare Nyirobi, which translates to "the place of cool waters". However, it is popularly known as the "Green City in the Sun" and is...

, Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

, calculated that Uganda was releasing about twice as much water as is allowed under the agreement, and was primarily responsible for recent drops in the lake's level.

Transport

Since the 1900s Lake Victoria ferries
Lake Victoria ferries
Lake Victoria ferries are motor ships carrying freight and passengers between Uganda, Tanzania and Kenya on Lake Victoria...

 have been an important means of transport between Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

, Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

 and Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

. The main ports on the lake are Kisumu
Kisumu
Kisumu is a port city in western Kenya at , with a population of 355,024 . It is the third largest city in Kenya, the principal city of western Kenya, the immediate former capital of Nyanza Province and the headquarters of Kisumu County. It has a municipal charter but no city charter...

, Mwanza
Mwanza
Mwanza is a mid-sized port city on the southern shores of Lake Victoria in northwestern Tanzania. With an urban population of 1.2 million and a metropolitan population of 2 million, it is Tanzania's second largest city, following Dar es Salaam and ahead of other major Tanzanian cities of Arusha,...

, Bukoba
Bukoba
Bukoba is a town in northwest Tanzania on the western shore of Lake Victoria. It is the capital of the Kagera region. Population estimate: 100,000...

, Entebbe
Entebbe
Entebbe is a major town in Central Uganda. Located on a Lake Victoria peninsula, the town was at one time, the seat of government for the Protectorate of Uganda, prior to Independence in 1962...

, Port Bell
Port Bell
Port Bell is a small industrial centre in the greater metropolitan Kampala area, in Uganda. Port Bell has a rail link and a rail/road ferry wharf used for International traffic across Lake Victoria to Tanzania and Kenya.-Location:...

 and Jinja
Jinja, Uganda
Jinja is the largest town in Uganda, Africa. It is the second busiest commercial center in the country, after Kampala, Uganda's capital and only city. Jinja was established in 1907.-Location:...

. Until Kenyan independence in 1963 the fastest and most modern ferry, , was designated a Royal Mail Ship
Royal Mail Ship
Royal Mail Ship , usually seen in its abbreviated form RMS, a designation which dates back to 1840, is the ship prefix used for seagoing vessels that carry mail under contract by Royal Mail...

. In 1966 train ferry
Train ferry
A train ferry is a ship designed to carry railway vehicles. Typically, one level of the ship is fitted with railway tracks, and the vessel has a door at the front and/or rear to give access to the wharves. In the United States, train ferries are sometimes referred to as "car ferries", as...

 services between Kenya and Tanzania were established with the introduction of and . The ferry MV Bukoba
MV Bukoba
MV Bukoba was a Lake Victoria ferry that carried passengers and cargo between the Tanzanian ports of Bukoba and Mwanza. On 21 May 1996 she sank with great loss of life, reported as up to 1000 passengers drowned. This occurred in of water, off Mwanza....

 sank in the lake on May 21, 1996 with a loss of between 800 and 1,000 lives, making it one of Africa's worst maritime disasters.

External links


Institutions of the East African Community
East African Community
The East African Community is an intergovernmental organisation comprising the five east African countries Burundi, Kenya, Rwanda, Tanzania, and Uganda. Pierre Nkurunziza, the President of the Republic of Burundi, is the current Chairman of the East African Community. The EAC was originally...

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