Nancy Chege*
ake Victoria—shared by Kenya, Tanzania, and Uganda—is the world's largest tropical lake and the second largest freshwater lake. Covering a total of 69,000 sq. km. (43,000 sq. mi.), the lake is about as large as the State of Louisiana, and lies in the Rift Valley of East Africa, a 3,500-mile-system of deep cracks in the earth's crust running from the Red Sea south to Mozambique. Although this region of Africa is better known for its large cats and the huge herds of wildebeests, zebras, and antelopes that roam the Savannah plains, its most diverse and endangered ecosystems are to be found under water.
In recent years, the ecological health of Lake Victoria has been profoundly affected by:
• the rapidly growing population
• clearance of natural vegetation along the shores
• a booming fish-export industry
• the disappearance of several fish species native to the lake and the introduction of exotic ones
• prolific growth of algae
• the dumping of untreated effluent by several industries.
Much of the damage done is extensive and irreversible. Fish kills are on the rise and algae is prevalent. Traditional lifestyles of lakeshore communities have been disrupted and are crumbling. There is consensus among scientists that if an accelerated push to save the lake is not executed soon, this important body of water will no longer sustain the communities it has nurtured for so long.
Early in the twentieth century, a few decades after John Speke, a British explorer, "discovered" the source of the famous Nile River, European missionaries flocked to Victoria's watershed. They cleared the surrounding natural vegetation—denuding forests and draining swamps—to plant cash crops such as tea, coffee, and sugar. Over the years, the plantations have grown in size and number, and today, agricultural chemicals applied on the plantations are washed into rivers and end up in the lake, providing nutrients for unwanted, unsightly algal blooms.
The Nile Perch: Survival of the Fittest
The plantations attracted migrant workers in search of a higher standard of living. As the population grew and fishing technologies improved, overfishing became a threat to the fishing industry, and catch sizes began to drop. By the 1950s, popular species such as ngege (Oreochromis esculentus), an endemic tilapia, had diminished so severely that they had become commercially extinct. To remedy the situation, British officials introduced new fish in the Lake's waters: Nile tilapia (Orechromis niloticus) and Nile perch (Lates niloticus). At the time, the new fish constituted less than 2 percent of the Lake's fish biomass, while tiny fish known as cichlids made up 80 percent.
Biomass composition of the lake remained relatively constant up until the late 1970s, but in 1980 a survey of the Lake revealed an abrupt and unexpected reversal in biomass composition. Cichlid numbers had fallen drastically, and were now only 1 percent of fish weight, while those of the Nile perch had suddenly jumped to 80 percent.
The decline in cichlid population has far reaching effects. Cichlids can easily alter their tooth and skull morphology to suit different eating patterns. Some feed on fish eggs, others on insects, while the majority prefer detritus. Since their numbers have dropped precipitously, cichlids feed on only a small portion of the detritus, leaving the rest to sink to the floor. As the detritus rots, it consumes oxygen, further depleting the oxygen concentration, and rendering some of the lower zones of the lake practically uninhabitable.
The explosive evolutionary nature of cichlids has drawn ecologists to Lake Victoria for decades. In only about 14,000 years, as many as 400 species of cichlids evolved from 5 species, making Lake Victoria one of the most species-diverse lakes in the world. However, the number of cichlid species has plunged to 200, thanks to the Nile perch. Les Kaufman, a chief scientist at Boston University, described the loss of half the cichlid species as "the greatest vertebrate mass extinction in recorded history." The Nile perch is a voracious predator which can grow to a hefty six-foot, 200 pound giant by feeding primarily on smaller fish.
Economic Impact
Cichlids and other fish species are not the only victims of the degraded lake. Local fishermen, whose families have relied on the lake for many generations, are also suffering largely because the wealth of the lake is being siphoned off to the accounts of affluent and influential people. The populations of native fish, which traditionally were a source of livelihood, have been decimated either by larger predators or by overfishing. The remaining stocks of commercial value are mainly the big, oily Nile perch, locally known as mbuta. But it is too far in the open waters for the small fishing boats used by local fishermen, and too big to be caught in their unsophisticated nets. Moreover, according to the lakeshore dwellers, it doesn't taste half as good as ngege.
The introduction of the Nile perch is viewed as an economic booster, not by the local communities close to the lake, but by successful businessmen and powerful government officials. Hauled by the ton from the open lake by large, commercial boats, the fish are sold to nearby foreign-owned processing plants where they are rapidly cleaned, filleted, boxed, and frozen, and sent off to prohibitively expensive restaurants in Nairobi and stores in the Middle East and Europe. The Nile perch has indeed become a money-churner. Its hide is used to make belts and purses, while its bladder is sold to alcohol distillers in England who use it as a filter, and to Asia where it's used to prepare soup stock.
Although the perch has enriched the pockets of a few elite and brought much needed revenue into the countries surrounding the lake, its introduction to the lake and its successful adaptation are not favorably regarded by scientists. In fact, biologists and conservation experts perceive it as an ecological disaster.
There is a seemingly insatiable international demand for the Nile perch and other lake fish. To meet this demand, commercial fishing fleets have established themselves, displacing local fishermen and stripping many women in lakeside communities of one of their primary sources of income. Cleaning and processing of fish was traditionally performed by women, but has now been taken over by large filleting plants. The women have resorted to processing fish waste, called mgongo-wazi—"bare-back"—in Swahili. The waste, comprised of the head, backbone, and tail, is sun-dried and then deep-fried and sold to local people drawn to its low price and nutritional value.
Industrial Waste
A number of industries have sprouted around the processing plants, varying from textile and leather-tanning to paper mills and breweries. Most of these are in Tanzania and Kenya, and are notorious for discharging untreated effluent in the lake. A recent study shows that on a daily basis, Tanzania is responsible for 2 million liters of untreated sewage and industrial waste that flow into the lake. Although Kenya has strict pollution laws, they are rarely enforced because the industries have ties with foreign investors and the government often has a significant stake in the polluting units. Moreover, it is considerably cheaper for the industries to pay an occasional 10,000 shilling fine (US$250) than to install equipment to treat effluent at a cost of US$2 million.
The Merciless Water Hyacinth
A more recent threat to the lake is the water hyacinth. With the deceptive appearance of a lush, green carpet, the hyacinth is a merciless, free-floating weed that reproduces fervently, conquering any uncovered territory. Since 1989, the weed has spread rapidly, covering areas in all three lakeshore countries. It forms a dense mat, blocking sunlight for organisms below, depleting the already low concentrations of oxygen and trapping fishing boats and nets of all sizes. The hyacinth is an ideal habitat for snails that cause bilharzia and for snakes.
Scientists are working constantly to combat the weed. One of their most promising approach involves harvesting the hyacinth and using it either for compost or for biogas production.
Public Health Concerns
The health implications of the dilapidated state of the lake are extensive. Dumping untreated sewage in the lake and nearby rivers exposes people to waterborne diseases such as typhoid, cholera, and diarrhea. In addition, as fish prices soar beyond the average person's reach and fish catch continues to fall, protein malnutrition may become widespread. This would be ironic, considering that over 200,000 tons of fish are exported from this region annually.
After the Rwandan carnage in 1994, certain parts of the lake were considered disaster areas by the Ugandan government, after thousands of bodies had floated into the lake via the Kagera River. To prevent the outbreak of an epidemic, people fished out bodies from the lake along the Ugandan-Tanzanian border. Bodies entangled by the hyacinth made the task markedly more difficult. During this crisis, the governments of all three countries were reported to be working closely to monitor the environmental situation.
Help is on the Way
Although the problems facing Lake Victoria may appear colossal and discouragingly complex, international and domestic efforts are underway to save the lake and halt its deterioration. The Lake Victoria Research and Conservation program has been working on understanding the biological functions of the lake and restoring endangered fish species. The program is funded by several international bodies including the US National Science Foundation (NSF), the Canadian International Development Research Council, and the Pew Foundation. To bolster these efforts, a workshop sponsored by the NSF was held in Jinja, Uganda in August 1992. It was attended by more than 70 scientists, policy makers, and government officials of the three riparian states. Upon careful examination of available evidence, it was concluded that a Lake Victoria Fisheries Commission was needed to harmonize research, management strategies, and monitor the Lake Victoria Basin. Recommendations of steps that should be taken included developing a general ecosystems model of the lake to understand and predict productivity, establishing fish parks to protect the diversity of native species, and promoting local participation in fisheries management.
Currently under review is a $20 million, five-year project to be funded by the World Bank, UN Development Program, UN Environment Program, and the UN Food and Agriculture Organization, through the Global Environmental Facility. The target date for implementation is May 1996. Some of the issues that will be addressed under this project are: control of the water hyacinth, land use management along the shores, and improvement of water quality.
At the grassroots level, a group of Kenyan professors, researchers, and community leaders called "Friends of Lake Victoria," or OSIENALA as abbreviated in the Luo language, is working to protect the interests of local fishermen and to encourage aquaculture. In order to ease the demand that is affecting the size and diversity of Lake Victoria's fish stocks, OSIENALA is cooperating with local groups to educate the many millions of people who are dependent on the lake about the advantages of fish farming. Elsewhere in the region, aquaculture is already offering an important alternative source of protein and income.
Lake Victoria should not be allowed to die. It is invaluable to millions who depend on it for food, employment, and recreation. Aggressive efforts by all sectors in the Kenya, Tanzania, and Uganda can enhance the quality of the lake and therefore the quality of life in the surrounding communities.
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* Nancy Chege is a Staff Researcher at the WorldWatch Institute, Washington, D.C.