Fish prefer to eat plastic over food – and it is killing them, study suggests

Microplastic particles appear to be killing fish because their larvae prefer to eat them rather than their actual food, researchers have warned.

With fears that the amount of plastic in the oceans could soon equal the weight of fish in the sea, scientists have become increasingly concerned about the effects on the marine environment.

Now a study published in the journal Science has found that baby perch will actively choose to eat plastic over the plankton they would normally feed on.

The researchers said this greatly increased mortality rates of the perch, stunting their growth and appearing to change usually innate behaviour.

For example, they seemed to lose the ability to smell a predator that made them much more vulnerable.

Professor Peter Eklov, a co-author of the Science paper, said: “This is the first time an animal has been found to preferentially feed on plastic particles and is cause for concern.

“Increases in microplastic pollution in the Baltic Sea and marked recruitment declines of the coastal keystone species, like perch and pike, have recently been observed.

“Our study suggests a potential driver for the observed … increased mortality.”

When placed in a tank with a pike, perch exposed to microplastic were eaten four times more quickly than perch that had not been eating plastic.

All the plastic-fed fish had been killed within 48 hours.

Fellow researcher Oona Lpnnstedt stressed the effects of prey fish eating large amounts of plastic was likely to be felt throughout the food chain.

“If early life-history stages of other species are similarly affected by microplastics, and this translates to increased mortality rates, the effects on aquatic ecosystems could be profound,” she said.

Microplastic is produced as larger pieces of plastic waste are broken down in the environment, but vast amounts of microfibers from synthetic clothes – things such as fleeces are essentially made of plastic – are produced each time they are washed and are small enough to pass through sewerage treatment plants and get into the sea.

Cosmetics companies are also continuing to put plastic microbeads into their products, with the industry saying it will try to phase them out by 2020.

Politicians are starting to realise the potential dangers of microplastics, which are small enough to pass through the gut wall and enter the tissues of animals.

One expert told a House of Commons committee that microplastics could also be getting into the atmosphere and contributing to air pollution that causes respiratory diseases.