Sea turtles eat ocean plastic because it smells like their prey

IT HAS long been thought that sea turtles mistake plastics for prey, particularly because to the human eye an inflated plastic bag can be easily mistaken for a jellyfish. However, scientists have found that the endangered creatures seek out and ingest plastics because they smell like food.

Research published in the journal Current Biology found plastics in the ocean trap microbes and algae, which then break down inside and release food-like odour, a phenomenon known as biofouling.

This leads the turtles into an “olfactory trap” in which they swallow the plastic, which can be deadly as pieces get trapped in their stomach and prevent them from digesting food.

Dr Kenneth J Lohmann, author of the study, from the University of North Carolina, said: “It’s common to find loggerhead turtles with their digestive systems fully or partially blocked because they’ve eaten plastic materials. There also are increasing reports of sea turtles that have become ill and stranded on the beach due to their ingestion of plastic.”

The researchers looked at 15 young loggerhead turtles brought up in captivity, studying how the creatures reacted to the smell of turtle food, ocean-soaked plastic, clean plastic and water.

In the laboratory, the turtles ignored the scents of clean plastic and water, but responded to the odours of food and ocean-soaked plastics by displaying typical foraging behaviour, such as repeatedly poking their noses out of the water and increasing their search activity.

No plastics were consumed during the experiments and the turtles were released into the ocean after the study, the researchers said.

Dr Lohmann added: “Once these plastics are in the ocean, we don’t have a good way to remove them or prevent them from smelling like food.

“The best thing we can do is to keep plastic from getting into the ocean at all.”