Could maggots fed on food waste replace wild fish feed?

A group of young Kenyans have come up with an unusual solution to the problems of food waste and unsustainably produced fish feed from wild fish stocks: maggots.

Black soldier fly larvae devour unwanted food in projects around the world. Their droppings, called frass, can be used as fertilizer for land crops, and their protein-rich bodies, harvested before they turn into flies, can be fed to livestock.

In Kenya, environmentalists behind the Mila Project, which means tradition in Swahili, are using the larvae to clean up food waste, as well as to maintain mangroves and feed fish on coastal farms.

Don’t waste, don’t lack anything

The Mila Project team of volunteers collects organic waste from households, markets and restaurants in the southeastern coastal city of Mombasa and feeds it to voracious larvae, which produce excrement while helping to clean up the city.

Nusra Abed, co-founder of the Mila Project and a community health promoter, says she was “disturbed by the number of sanitation-related infections in the community due to poor waste management, and wanted to be part of the solution.”

According to a report by the United Nations Environment Programme, Kenya has one of the highest levels of domestic food waste in the world, producing between 40 and 100 kilograms per person per year.

In addition to reducing the problem of food waste, the excrement has also helped smallholder farmers in the Mombasa region increase the growth and diversity of their crops. It allows farmers to diversify their production from coconuts, a common crop that takes a long time to mature, to fast-growing crops such as onions, tomatoes and other fruits. This gives them the opportunity to earn extra income through sustainable and organic farming, and to sell their surplus crops in markets, notes Roselyne Mwachia, a marine and fisheries researcher working with the Mila project.

Using excrement in agriculture has also made the activity less harmful to the environment and improved the catches of nearby fishermen, with fishing being the most common economic activity for people living along the Kenyan coast.

In areas like Mariakani and Mazeras, 38 kilometres west of Mombasa, upstream smallholder farmers used chemical fertilisers before switching to excrement, which polluted the marine ecosystem when it was washed into the water after storms, Mwachia explains. “This has affected… marine species, as well as caused coral reef bleaching and the death of mangroves, seagrass and algae,” she tells Dialogue Earth.

“Coral reefs are fertile breeding grounds for marine species, and when bleaching occurs, it means that breeding will be affected and marine stocks will decline,” she adds. But with farmers turning to excrement, Mwachia notes that “fishermen in the areas where we have worked report reduced coral bleaching and increased fishing profits due to reduced pollution.”

Create more mangroves

In addition to reducing pollution reaching the sea, the Mila project attempts to cultivate healthy marine ecosystems more directly.

Kenya’s mangrove forests develop roots that protect the coastline from erosion, provide habitat for marine species, and are very effective at trapping carbon dioxide. However, the country’s mangroves are constantly eroding. Recent estimates are hard to come by, but between 1985 and 2010, Kenya lost an average of 0.7 percent of its mangrove cover per year, according to a 2011 study. Harvesting for firewood has been cited by Kenya’s Ministry of Environment as a major cause of mangrove deforestation in the country.

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Many families living along the coastline rely on mangroves as a source of fuel and charcoal, says Ahmed Abeid, Mila project coordinator. “Having families engage in alternative activities like organic farming helps reduce the pressure (on the mangroves).”

The project plans to start using the excrement to make briquettes, which could replace mangrove wood as a fuel source, he adds.

The Mila project also works directly on mangrove restoration. The excrement is used to nourish young mangrove plants in nurseries, which are then planted in areas prioritized by the Kenya Marine and Fisheries Research Institute (KMFRI) and the Kenya Forest Service due to their high levels of forest degradation. These areas include three streams on the outskirts of Mombasa – Bidii, Turdo and Mtwapa.

Rose Chiteva, a senior researcher at the Kenya Forest Research Institute, says soldier fly droppings help mangroves thrive: “Mangroves planted with droppings show faster growth and higher survival rates (because it) helps neutralize the acidity of soils in mangrove forests.”

Encouraging sustainable aquaculture

Maggots are also attracting the attention of Kenyan fish farmers.

Aquaculture has earned a bad reputation globally for its unsustainability, particularly due to the widespread practice of processing wild-caught fish into feed for captive-bred fish. Yet producing fish feed from fly larvae has the potential to reduce reliance on traditional fishmeal derived from wild stocks, notes Mary Opiyo, a senior aquaculture researcher at the government-run KMFRI.

“It’s a way to promote sustainable aquaculture and reduce over-reliance on marine stocks,” she says.

Kigen Compton is the founder of BioBuu, a company that produces fish feed from black soldier fly larvae in Kenya and Tanzania. He says, “With readily available, available and affordable feed, many farmers are moving towards sustainable aquaculture and away from wild fishing.”

The larvae have also attracted more distant aquaculture workers.

In Colombia, rural people are making a sustainable living from insects fed on excrement that are used as feed in fish farms. A Finnish company claims that producing fish feed from the larvae is the “ideal solution” for the aquaculture of the future. Researchers in the United States recently did some calculations on the country’s aquaculture industry. They found that if soldier fly proteins were fed to salmon, trout and shrimp to the maximum extent possible without harming the fish’s performance, 40,843 tons of wild fish could be saved each year.

Flies in the ointment?

As maggots take root in aquaculture, some see trouble ahead.

David Mirera, a senior researcher at KMFRI, says there is a risk of disease if proper hygiene guidelines are not followed during the production of these fish feeds.

“We do not have a clear regulatory framework or controls on the breeding of the black soldier fly, which could compromise the quality of food produced, especially by those who are not professionals in the food formulation and production sector,” he says.

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But many fish farmers in his country are already big fans of the flies, which are practical and safe in terms of yield. Juma Mashanga is one of them. He leads a group of community fishermen who raise fish in cages in the Indian Ocean near Kwale, a town 30 kilometres southwest of Mombasa.

“With cages, we have the guarantee of harvesting at maturity and the yields are good,” he says. “Maintaining the cages and feeding the fry is manageable because we can process our protein feed (for the black soldier fly) at home.”