Misuse of Mosquito Nets Stressing Lake Malawi’s Fish Populations

Mosquito nets distributed by international aid organizations to fight malaria are being used by some who live along the banks of Lake Malawi to indiscriminately harvest fish, aggravating the lake’s already rapidly diminishing fish stock. 

Lake Malawi — home to more species of fish than any lake in the world, including the world’s largest reserves of endangered cichlids — is also a critical source of sustenance for millions of people in this region of eastern Africa. But a public health device that has helped save human lives is contributing to the depletion of the lake’s once-abundant fish.

Women fish with a mosquito net, a practice that has contributed to overfishing.

Women fish with a mosquito net, a practice that has contributed to overfishing. LTFHC

Over the last 15 years, UNICEF and the government of Malawi have rolled out 9 million free mosquito nets to guard the health of pregnant mothers, their offspring, and refugees against the ravages of malaria. This has been a public health triumph. According to the World Health Organization, deaths from malaria in Africa have been reduced by half since 2000.

But the mosquito nets are also being used by impoverished villagers for netting fish in Lake Malawi, contributing to the rapid decline of the lake’s fish stocks, which dropped 93 percent between 1990 and 2010, according to most recent statistics available from the UN’s Food and Agriculture Organization. Overpopulation and deforestation also contribute to the problem, but misuse of mosquito netting is playing a significant role.

“The mosquito nets have deadly tiny holes,” said Chuene Mwale, a government biologist heading conservation efforts for Senga Bay district, one of the biggest communities near the lake. “They scrub the lake’s floor, scooping up everything. Not even tilapia fish varieties listed on the [International Union for Conservation of Nature] endangered list are spared.” Adding to the problem is that the nets are treated with permethrin, a toxic insecticide that is particularly poisonous to aquatic animals.

“The mosquito nets are written: ‘Don’t wash or pour in water,’” said Teko Zwandili, 35, an ornamental fish merchant who operates near Lake Malawi National Park “But many people, particularly women, children, and the aged can’t afford to buy a $400 fishing boat. What do they do? They use mosquito nets to scoop fish.”

When asked about baskets made from reed, which are more friendly to fish, the fish seller protested. “There is biting food hunger here. Reed baskets take seven days to build. Mosquito nets are instant.” William Chadza, head of the Centre for Environmental Policy and Advocacy, a leading local think tank, says he is not surprised by the destructive impact of mosquito nets on fish. “The communities around Lake Malawi are troubled by large-scale poverty, with rates of 62 percent,” he said. “Hundreds of kids who don’t attend school spend the day drying fish on poisonous mosquito nets, and later sell them at bus terminals and police checkpoints.”

Lake Malawi is the food basket for this region of Africa. The 11,429-square-mile lake employs 250,000 people directly or indirectly; its waters support transport, electricity, irrigation, and food for millions in Malawi and the neighboring countries of Tanzania and Mozambique; and its fish provides Malawians with the majority of their protein intake.

The drop in fish stocks has become increasingly noticeable. “In the past, a fisherman would harvest 3,000 chambo a day,” says Jairos Woyo, a traditional chief in Senga Bay where the fish trade used to be big business. “Today men sail deep into the lake, and they rarely return with 400 if they’re lucky.”

Chambo is a species of the tilapia fish family, a sought-after regional delicacy. Due to overfishing, stocks of chambo have sunk by 70 percent in the past 12 years, and its market price has skyrocketed, according to Bino Muluzi, a senior statistician with the Malawi Fisheries Department. This lucrative market price has sparked conflict between communities on the lake and outside fishermen who descend on the lake at night with mosquito nets, Muluzi says. “Fights break out between fishermen who dream of quick profit and locals who fear nets will ruin the future.”

In the past, there was a tendency to impose top-down conservation measures on the local lake population. More recent initiatives seeking to suppress the use of nets on the lake are led cooperatively by communities, traditional leaders, and charities. 

Ripple Africa, an international charity, has worked to establish local committees that work with authorities to educate people about the dangers of overfishing, particularly with the use of mosquito nets, and to develop local bylaws for an annual four-month fishing ban that allows for breeding. Jessica Kirenji, 39, a former fisherwoman, says she has benefited from a program run by the United Nations Development Programme that seeks to help local communities develop other sources of food and income. “We are trained to diversify our income from fish farming to dairy cattle farming,” she says. “Personally I have four cows now and I can buy salt, soap, and medicine. My life no longer depends on fish.”