Cheap fish food: Palm oil, lowly maggot poised to boost income, cut pollution

Hard-pressed farmers in developing countries could be thrown an economic lifeline after a lucky discovery by French scientists involving a useless palm oil by-product and the lowly maggot.

The synergy of two otherwise nuisance agents produced a virtually cost-free feed for farmed fish while reducing a pungent source of pollution -- a potential boon in countries like Indonesia, one of the world's largest palm oil producers.

"This process will allow us to recycle palm oil refinery waste and turn it into cheap food for fish farms and to produce 'green' fertiliser," Saurin Hem, a researcher at the Institute for Research and Development (IRD) in the southern French port of Marseille, told AFP.

After an IRD team stumbled onto the discovery they perfected the technique with partners from Indonesia, which churns out almost 2.3 million tonnes of palm oil a year.

Jakarta is set to start using the method this year at a refinery on the western island of Sumatra, IRD said.

The unlikely players in this small miracle are the tiny, squirming larvae reviled the world over -- maggots -- and a by-product from an industry in tropical Africa and Southeast Asia that is often maligned by environmentalists opposed to the expansion of plantations into rainforests and other delicate habitats.

Palm oil production generates millions of tonnes of biomass called palm kernel meal that can foul nearby waters and produces methane, a potent greenhouse gas.

Some palm kernel meal is exported to Europe, the United States and Australia as cattle feed, but the majority is largely left to rot, emitting the foul-smelling, polluting gas in hot tropical settings.

Parallel to this, local populations eking out a living in palm-growing developing states have increasingly turned to fish farming to earn a bit of income and provide themselves with an important source of protein.

The problem is that many of these rural dwellers don't have enough money to nourish the fish to maturity. Until now -- when the IRD team stumbled across a new way to convert the unwanted meal into fish food.

The French scientists at IRD had been tasked with finding a way of making palm kernel -- rich in fats and proteins -- suitable to feed to fish.

Testing began in the west African state of Guinea with a mixture fed to a 400-strong shoal of tilapia fish, commonly farmed in Asia and Africa for their large size and rapid growth.

But the experiment failed -- the fish wouldn't bite, and left the palm kernel meal untouched.

Researchers dumped the fermented mixture well outside the IRD's laboratory owing to its strong smell.

Two weeks later they noticed something strange: chickens and other birds were pecking furiously at the rotting refuse, feasting on maggots. A species called black solider flies had been attracted by the smell and laid eggs.

That was the scientists' eureka moment: enzymes secreted by the fly larvae, it turned out, had changed the chemistry of the fermenting mixture.

Wondering if the fish would find it more digestible, they tried again. This time, the tilapia grew 3.5 times faster than with previous feeds, and gained three times as much weight per day.

Experts like Boris Patentreger, head of head of forestry conservation at the World Wildlife Fund (WWF), welcome the findings but warn about the Catch-22: any increase in palm oil production should not cause further deforestation.

"It's a very good initiative which helps recycle waste and avoids creating more dangerous greenhouse gases. On the other hand, we must make sure we have sustainable palm oil production," he told AFP.

The use of palm oil, reputedly free of artery-clogging trans fats, has soared in the commercial food industry, notably in the United States and Europe where it is found in everything from cookies to soups to sandwich spreads.

It is also used as a biofuel in the craze to find renewable energy sources. Environmentalists say these factors have already caused the destruction of numerous tropical forests, cleared to make way for bigger plantations.

IRD researcher Hem shared the concerns about protecting the environment.

"To be able to recycle the waste, we must not destroy the insect's natural habitat, that is to say the forest," he said.