Plastic in the sea smells like food to fish – study

PLASTIC starts to smell like food to fish after it has been in the sea, according to research that sheds new light on how the artificial, toxic substance is entering the food chain.

Concern is growing that plastic is accumulating in the tissues of marine life as it gradually breaks down until it is small enough to pass through the gut wall into the bloodstream and even muscle tissue.

Recent research estimated that 6.3 billion tons of plastic waste has been created since the 1950s, when its use became widespread. Most of this has been thrown away in what scientists described as an “uncontrolled experiment on a global scale”. More than 50 species of fish are known to eat plastic and 700 marine species are exposed to it.

In a study reported in the journal Science last year, baby perch were found to actively prefer to eat plastic over plankton. The research, which tested the responses of anchovies, found a significant reason plastic was so attractive.

The scientists tested the responses of wild-caught fish to odour solutions made from plastic that had been left for three weeks in the sea compared with “clean plastic”. The biofouled, but not the clean, plastic was found to “stimulate a behavioural response consistent with foraging in captive anchovy schools”.

“This is the first behavioural evidence that plastic debris may be chemically attractive to marine consumers,” the researchers wrote in the journal Proceedings of the Royal Society B: Biological Sciences. “These chemical cues may lure consumers, such as anchovy, into regions of high plastic density and activate foraging behaviours, thus making it difficult to ignore or reject plastic items as potential prey.”

The researchers, from University of California, Davis, and San Francisco’s Aquarium of the Bay, added that plastic accumulated chemicals that were used by some fish, seabirds and sea turtles to find food. “It is not surprising that (these species) are frequent consumers of plastic debris. In addition, plastic debris has visual cues (colour and shape) that may resemble prey; visual and chemical cues associated with plastic debris likely interact synergistically, exacerbating this evolutionary trap.”

Given plastic’s attractiveness to marine life eaten by humans, there is concern it could start to become a problem for us. The researchers recommended further research into the negative effects of plastic in the marine food chain, such as increased risk of predation. “Humans are at the top of these food chains; therefore, results of such future studies may have important consequences for human health,” they said.

In addition to attracting smells associated with food, plastic also accumulates toxic chemicals in the natural environment. Other scientists have concluded this effect is so pronounced that plastic should be treated as a toxic substance once it gets into the environment. – The Independent

“MORE THAN 50 SPECIES OF FISH ARE KNOWN TO EAT PLASTIC AND 700 MARINE SPECIES ARE EXPOSED TO IT