Fish Actively Consume Marine Plastic Debris As It Smells Like Food

Plastic debris in the ocean breaks down into tiny pieces that are then consumed by the fish. Rich Carey/Shutterstock

With plastic predicted to out weight fish in the oceans by 2050, the problem of plastic pollution is not one to be underestimated. But new research suggests that the issue may be even more serious than we thought, as it has been discovered that fish may be actively seeking out plastic to eat, rather than consuming it by accident as was usually thought.

More than 50 different species of marine fish, many of which we ourselves then eat, have been found to ingest tiny bits of plastic. Because of this, and the damage the vast amounts of plastic pollution in our oceans will cause not only marine animals but our own health too, it is vital to understand how and why fish are snacking on the plastic.

To discover whether or not the fish are eating the plastic by accident or on purpose, the researchers tested a school of anchovies in the lab. They presented the little fish with a range of odor solutions, one made from plastic debris, while the other was created using clean plastic instead.

The tiny anchovy is not only an important food source for us, but also many other predatory fish in the ocean. zaferkizilkaya/Shutterstock

The scientists found that the solution of plastic debris elicited the same foraging behavior as odors derived from their natural foodstuff, suggesting that the fish actually thought that the plastic debris was food. When they tested the clean plastic, they found that there was no response from the anchovies.

Publishing their results in the Proceedings of the Royal Society B, the researchers think that as plastics break down in the ocean, they emit a similar smell to their preferred prey. This is the first time that it has been shown that anchovy fish use odor to forage, and has some serious implications for plastic pollution.

“These results demonstrate that odours associated with plastic debris stimulate a behavioural response consistent with foraging in captive anchovy schools,” explained first author Matthew Savoca, to the Telegraph. “This is the first behavioural evidence that plastic debris may be chemically attractive to marine consumers. These chemical cues may lure consumers, such as anchovy, into regions of high plastic density and activate foraging behaviours.”

This discovery, if verifiable with field observations and more experiments, should be of utmost concern. Rather than the fish simply consuming the plastic by accident as they gobble up their normal prey of krill, it seems that they might be actively seeking out the tiny chunks of plastic as they think the inorganic matter is the krill itself.

This is a significant problem, because as the plastic accumulates in the anchivies, it is likey passed onto those animals that eat them in turn, including us. 


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