A group of young Kenyans are working on an unusual solution to the problems of food waste and fish feed produced unsustainably from wild-caught fish stocks: maggots.
The larvae of the black soldier fly are now devouring unwanted food in projects around the world. Their excrement, known as frass, can be used as a fertiliser for land-based crops, and their protein-rich bodies, harvested before they turn into flies, can be fed to livestock.
In Kenya, the environmentalists behind Project Mila, which in Swahili means tradition, are employing the larvae to clean up food waste, as well as nurture mangroves and feed fish in coastal farms.
Project Mila’s team of volunteers collect organic waste from households, markets and restaurants in the south-eastern coastal city of Mombasa, and feed it to voracious larvae, which produce frass while helping to clean up the city.
Nusra Abed, co-founder of Project Mila and a community health promoter, says she was “perturbed by the number of sanitation-related infections within the community due to poor waste management, and wanted to be part of the solution”.
According to a report by the UN Environment Programme, Kenya has some of the highest levels of household food waste in the world, producing 40-100kg per person annually.
Apart from alleviating the problem of food waste, the frass fertiliser has also been helping small-scale farmers in the Mombasa area increase their crop growth and diversity. It can enable farmers to diversify away from planting coconuts – a commonly grown crop which is slow to mature – into fast-growing produce including onions, tomatoes and other fruits. This offers them the opportunity to earn extra income through farming that’s sustainable and organic, and selling their surplus harvest in markets, says Roselyne Mwachia, a marine and fisheries researcher working with Project Mila.
The use of frass in farming has also made the activity less harmful for the environment and improved the catch of nearby fishers, say the team. In areas like Mariakani and Mazeras, 24 miles west of Mombasa, upstream smallholder farmers were using chemical-based fertilisers before the switch to frass, which polluted the marine ecosystem when washed into the water after storms, says Mwachia. “This affected … marine species, as well as caused bleaching of coral reefs and death of mangroves, seagrass and seaweeds.”
“Coral reefs are fertile breeding grounds for marine species, and when bleaching happens, it means breeding will be impacted and marine stocks will reduce,” she adds. But with farmers shifting to frass, Mwachia says that “fishers around areas where we have worked are reporting reduced coral bleaching and increased fishing fortunes due to reduced pollution”.
Globally, aquaculture has gained a bad reputation for its unsustainability, especially relating to the widespread practice of turning wild-caught fish into food for captive-bred fish. But making fish feed out of fly larvae can potentially reduce dependence on traditional fishmeal derived from wild stocks, notes Mary Opiyo, a senior aquaculture research scientist at KMFRI, a state body.
“This is one way of promoting sustainable aquaculture and reducing overreliance on marine stock,” she says.
Kigen Compton is the founder of BioBuu, a company producing fish feed from black soldier fly larvae in Kenya and Tanzania. He says: “With easily accessible, available and affordable feeds, many farmers are shifting to sustainable aquaculture and moving away from wild fishing.”
The larvae have been catching on with aquaculture workers in other countries, too. In Colombia, rural populations are earning sustainable livelihoods through frass-fed insects that are being used as feed in fish farming, while a company in Finland says producing fish feed from the larvae is the “perfect solution” for future aquaculture. Researchers in the US recently made some calculations regarding the country’s aquaculture industry. They found that if soldier fly protein was fed to salmon, trout and shrimp to the maximum extent without impairing the fish, 40,843 tonnes of wild fish could be spared every year in the US alone.
There are some concerns about disease. David Mirera, a senior research scientist at KMFRI, says there are risks if proper hygiene guidelines are not followed during the production of the feed. “We do not have a clear regulatory framework and controls on black soldier fly rearing, and this might compromise the quality of feeds being produced, especially by those who are not professionals in the sector of feed formulation and production,” he says.
But many fish farmers in his country are already firm fans of the flies, citing their convenience and secure yields. Juma Mashanga is one of them. He helps lead a group of community fishers who are farming fish in cages in the Indian Ocean near Kwale, a town 19 milles south-west of Mombasa.
“With cages, there is a guarantee of harvesting at maturity, and the returns are good,” he says. “Sustaining the cages and feeding the fingerlings is manageable because we can process our [black soldier fly] protein feeds at home.”
