Fish Mistake Scent of Plastic for Food

Researchers have found that fish often mistake the scent of plastic for food, which means ingestion of this deadly material may not always be accidental. 

Plastic is one of the main threats to marine life. Now, researchers have discovered that it’s even more dangerous than previously thought. Not only does plastic pollute marine environments and entangle marine life, it also appears that fish mistake the scent of plastic for food and might ingest it on purpose.

A recent study on anchovies has shed light on the problem. While scientists have long known that some 50 species of sea creatures eat plastic trash, they don’t know why. Some animals may mistake the trash for something else. Turtles, for instance, seemingly mistake floating, semi-transparent plastic bags for jellyfish. But this doesn’t account for all instances.

Fish mistake scent of plastic for food

The researchers subjected wild anchovies, caught off the California coast, to various food odors. Researchers created the odors by soaking various substances in seawater. This created what the researchers termed “sea-tea,” because the process resembled steeping a tea bag to make tea. They made one of the sea-teas with krill, a natural food source for anchovies, which they used as a baseline for testing other substances.

Tellingly, the fish didn’t respond to clean plastic. They did, however, respond similarly to the baseline “sea tea” test when researchers subjected them to the odor of bio-fueled plastic, which is covered in algae and microbes. This is a common occurrence when plastic spends extended time in the ocean.

This lends credence to the theory that fish simply mistake floating plastic debris for food, which causes all kinds of problems. First and foremost, eating plastic kills many marine animals. Even if fish survive after ingesting plastic, the material then enters the ocean’s food chain. As larger fish eat the smaller fish, like anchovies, the plastic — and the toxins within — move up the food chain, ultimately reaching humans.

While proposing new solutions is outside the study’s scope, it does lend even more urgency to the need to regulate plastic use, as well as taking measures to prevent plastic from entering the ocean in the first place.