Fish are chemically attracted to the smell of plastic waste in the sea, a study has suggested.
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The extensive investigation shows that odours from discarded plastic induce food search behaviours in fish, confusing plastic for prey. This is the first behavioural evidence that the chemical signature of plastic debris is attractive to marine fish.
The research, published in the Proceedings of the Royal Society B: Biological Sciences, demonstrates that many species of marine fish could be affected by this attraction, including those sold for human consumption.
Schools of Northern Anchovy found in the North Pacific were the focus of the study. However, “the results are relevant to fish all over the globe and could extend to fresh water fish also”, warns study author, Matthew Savoca of the National Oceanic and Atmospheric Administration in the US.
A chemical signature is an odour associated with a particular item, in this case, plastic debris. When plastic floats at sea it gets coated with various bacteria and algae. “These lifeforms emit distinctive sulphur compounds, in particular, dimethyl sulphide, which many marine animals use to locate biologically productive areas in the ocean for foraging”, Savoca explains.
This results in the chemical attraction of fish to plastic waste and consequently high rates of plastic consumption.
It is well known that the consequences of this consumption have high environmental costs on marine life. “Most often fish suffer damaging effects from ingested plastic including malnutrition and liver failure”, says senior pollution policy officer at the Marine Conservation Society, Sue Kinsey. This can lead to slower growth, reduced capacity for movement and subsequently limited reproduction.
This is not the first study that focuses on the consumption of plastic by marine life. However, it is the first clear evidence that marine fish are chemically attracted to plastic as a source of food. This latest study was recorded over 2.5 years in Aquarium of the Bay in San Francisco, California.
The implications for human health are not yet fully understood. However, a 2014 study conducted by Lisbeth Van Cauwenberghe and Colin Janssen found that the average European seafood consumer ingests 11,000 plastic particles a year.
“Small or microplastic pieces under 5mm occur either as a result of the breakdown of larger objects or through items such as microbeads from personal care products or wear and tear from tyres”, Kinsey explains.
However, the problem can be tackled. “The two main things that people can do every day is recycle and reduce their dependence on single-use plastic items,” advises Savoca. That includes everything from shopping bags, straws and disposable water bottles.
Charles Clover, the executive director of the Blue Marine Foundation, emphasises that the solution to the problem lies on land. “More broadly, the international community needs to do more to help the handful of less developed countries that produce most of the plastic waste.” They do this often because waste systems are not as well developed as they are in richer nations.
“We must be prepared to be more tolerant of basic solutions in these places, such as incineration,” says Clover.
Savoca says that this study should remind us of the intrinsic value of healthy marine life and the importance of fish in sustaining healthy human populations as well.