Introduction

More than 400 species of native fish and other aquatic life once thrived in Lake Victoria, a huge expanse of water surrounded by forested mountains and open savannas. Whole populations gained a livelihood from fishing this freshwater lake, the second largest in the world. But then, during the early part of the century, fishermen felt pressured to increase their yield, and used nets with tighter meshes. They caught as many fish as they possibly could. The native species could not sustain themselves, and rapidly started to disappear.

The dwindling fish population was dealt another blow when, in 1954, British colonists introduced the Nile perch, a predator, for sport fishing. During the 1980s, the perches reproduced very rapidly, and large, well-capitalized companies established processing plants, refrigerator trucks, and ships to export the now-popular commodity. These companies also caught as many fish as they possibly could.

Like the native species before it, the perch started to decline. Desperate fishermen used a yet smaller mesh size to increase their yield, now catching immature perch before they even reproduced. Families who had fished for generations lost their ability to make a living, since now only larger companies who could afford larger ships, tightly meshed nets, and other expensive gear could continue to catch the smaller, much less abundant fish.

A lifetime ago 350 species of cichlids, a family of spiny-rayed, freshwater tropical fishes, swam the waters ofLake Victoria.

Now half of them are extinct, the largest mass extinction of vertebrates in the world.

Aquatic wildlife faces the same bleak future throughout the rest of Africa and the world. One tenth of the planet's coral reefs are already dead. Half its mangrove habitats are destroyed. Estuaries and bays are heavily polluted or destroyed, with the original life "all but gone" (NRC, 1995). The U.N. Food and Agriculture Organization estimates that nearly 70% of the world's marine resources are ":full to heavily exploited, over-exploited, depleted, or slowly recovering from overfishing" (FAO, 1994). The International Union for the Conservation of Nature added 100 marine fish species to its Red List in 1996, the majority threatened by overexploitation (SSC, 1998).

We can change that future. In the Tanga region of Tanzania, villagers manage the aquatic habitat themselves, inspecting fishing gear, patrolling to prevent the highly destructive dynamite fishing (People and the Planet, 1997), and replanting mangroves. They developed a sustainable seaweed farming industry to replace jobs that were destroying coral reef fishes (Intercoast Network, 1998).

Communities along the Phongolo floodplain, Natal, South Africa, have changed how they use their dam (Bruwer et al., 1996). The structure caused great damage when it was built in the 1950s because it eroded the soil, prevented natural flooding, and drastically altered where water was distributed. Seventy thousand people who depended on natural flooding for farming lost food and livelihood. The dam killed off a rich variety of river wildlife. But now the villagers artificially reflood the floodplain at carefully determined intervals, and maintain sustainable floodplain fisheries.

How Africa's People Depend on Aquatic Habitats

The people of Africa rely on aquatic habitats for many of life's essentials: food, water, income, electric power, and wastewater treatment.

Food

Many Africans face starvation, and have great difficulty getting enough protein. Lack of protein is a major cause of infant death and of slowed mental development. In many areas, the only affordable source of protein is fish.

Fish is irreplaceable, providing 25% of Africa's protein needs. It is the most consumed source in almost every riparian African state. Some countries derive more than 50% of their animal protein from fish—Ghana, the Democratic Republic of the Congo, Senegal, Sierra Leone, Uganda, and Malawi (USAID/R&D/AGR draft fisheries strategy, 1987). Fish contains an abundance of an essential amino acid, lysine, that is limited in grains.

Africans also use other aquatic plants and animals for sustenance. For instance, generations of people living near Lake Chad have relied on a blue-green algae, Spirulina platensis, as a protein-rich food (Leonard and Compere, 1967).

Fish help Africans grow food on land. They control insects and snails that spread disease in ponds and rice paddies, decreasing the need for chemical insecticides and molluscicides. Some fish can also control weeds in irrigation ditches, canals, and ponds, eliminating the use of herbicides. Fish provide a way to monitor pesticide runoff, organic pollution, siltation, and other agricultural problems.

Water

Is is not only wildlife that requires a safe and reliable water supply, But freshwater ecosystems struggle to satisfy humans' ever-increasing demand for water. Since 1940, the world's population has doubled, but its water consumption has almost quadrupled, primarily for agricultural uses (Stiassny, 1997, in press). This water must come from freshwater habitats that are rapidly degrading because of pollution and sedimentation.

Income

Fishing is a traditional way of life for many Africans, and a major source of income for the continent. In 1995, the total annual yield, both freshwater and marine, was an estimated five million tons. Exports alone were valued at $313.6 million (FAOSTAT database, 1997). Inland waters produced 1.8 million tons, surpassing the yield of North America.

Many wild fish populations furnish valuable genetic material for improving domestic fish strains used in aquaculture. In particular, pure strains of tilapia (a type of cichlid) are critically important to the aquaculture of developing countries. Unfortunately, habitat loss and the impact of exotic species threaten this species' existence.

Wetlands serve as feeding, breeding, and nursery for many commercially important fish and shellfish species. For example, the wetlands in the Banc d'Arguin National Park in Mauritania are vital to the country's offshore fishery, which contributed $34 million to the national economy in 1980 (IUCN, 1990a). More than half of Zambia's fish production comes from freshwater floodplains or wetland swamps (Harper and Mavuti, 1996).

In addition to fish, many Africans harvest marine invertebrates—mollusks, crustaceans, coral, and echinoderms (of the starfish family)—which have substantial commercial value (Gawler and Agardy, 1994).

Tourists visiting Africa's fascinating aquatic habitats provide vital income. The beautiful cichlid fishes of the Great Lakes, the abundant waterfowl and large mammals of the wetlands (Harper and Mavuti, 1996), and the colorful spectacle of the coral reefs—all attract curious outsiders. In 1988, Kenya generated more money from coastal attractions than from wildlife safaris (Samoilys, 1988a). Tourism is well established in Africa, and can be managed with the environment in mind by expanding grassroots ecotourism programs. Job-generating, habitat-friendly activities include cruises, non-motorized water sports, nature trips, and monitored sport-fishing.

Aquatic habitats help Africans raise their herds Floodplain grasses, with their high protein content, feed livestock (Gaudent, 1992). Pastoral communities that utilize floodplains move their herds onto arid, rain-fed land as the waters rise, and back onto the floodplains as the water recedes. The post-floodplain pastures of the delta support the highest density of cattle, sheep, and goats in Africa.

Africans derive income from their waters in many other ways, many of them sustainable. Wetlands supply fodder, timber, resins, medicines, meat, skins, honey, and eggs. Mangroves provide building materiels, firewood, reptile skins, charcoal, and honey. East Africans collect tannin, which is used to preserve fishing nets, ropes, and sails, from mangrove trees. Coral reefs generate cash from the aquarium trade, shellfish products, and chemical products.

Energy

Although Africa's 38,000 large dams have caused serious environmental problems, engineers can design dams that mimic the natural flow of water with controlled water releases (Stiassny, 1996). A country can both generate electricity and maintain a healthy, diverse ecosystem.

Africans also have smaller-scale methods of using aquatic habits for their fuel needs. Those living near mangrove habitats collect firewood, and some residents of Rwanda harvest and compress papyrus to create fuel briquettes (IUCN, 1990b).

Wastewater Treatment

Wetlands retain toxins and sediments, and play a major factor in replenishing water. "In Uganda, the National Sewerage and Water Corporation is supporting conservation of papyrus swamps and other wetlands in the Kampala area because of the role that these play in absorbing sewage and purifying the city's water supply" (IUCN, 1990b).