Fish eat plastic in the ocean because it smells like food, scientists discover
The reason why fish eat plastic when it is dumped in the
ocean has been discovered by scientists.
Tests on anchovies show that when plastic is mixed with salt
water and begins to disintegrate it releases an odour which is similar to
krill.
The enticing smell sets of foraging and feeding behaviour in
fish, causing them to eat the debris, believing it is food.
Previously scientists thought that fish were ingesting tiny
particles of plastic by accident when they were hoovering up floating pieces of
plankton or krill. But the new study suggests the problem is even more serious,
because fish are actually attracted to the plastic.
Writing in the Proceedings of the Royal Society B, first
author Dr Matthew Savoca of the University of California and the US
government’s National Oceanic and Atmospheric Administration, said: “These
results demonstrate that odours associated with plastic debris stimulate a
behavioural response consistent with foraging in captive anchovy schools.
“As when foraging, the anchovy responded to the medium and
high concentrations of biofouled plastic odour. Similar results were seen in
response to all concentrations of food odour, thus indicating anchovy use
odours to initiate foraging behaviours.
“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.”
“These findings have considerable implications for aquatic
food webs and possibly human health.”
To come to the conclusion scientists concocted a watery
mixture of krill, and a second solution of broken down plastic. They then added
it to a tank of anchovies to see their reaction. High levels of plastic set off
the same foraging behaviour as krill, although smaller amounts were ignored by
the animals.
Experts have calculated that by 2050 the world’s oceans will
contain more plastics than fish, by weight.
A recent study estimated that nine in 10 of the world’s
seabirds now have pieces of plastic in their guts, mainly through eating fish
which have ingested plastic.
A recent study by the University of Ghent in Belgium found
human seafood eaters ingest up to 11,000 tiny pieces of plastic every year with
dozens of particles becoming embedded in tissues.
If current trends continue, by the end of the century people
who regularly eat seafood could be consuming 780,000 pieces of plastic a year,
absorbing 4,000 of them from their digestive systems.
There are more than five trillion pieces of microplastic in
the world's oceans and the equivalent of one rubbish truck of plastic waste is
being added to the sea every minute.
By 2050 that will increase to four trucks every minute.
Speaking at the launch of a new campaign by Sky Ocean Rescue
to encourage people to recycle more plastic British explorer Sir Ranulph
Fiennes said: “I’ve explored some of the most remote and vast points of the
world and yet still witnessed the reach of ocean pollution.
“Between 1979 and 1982 my team completed the first surface
circumpolar navigation of Earth and during both the Atlantic and the Pacific
voyages we witnessed the amount of pollution, much of which was plastic and
that was just on the surface.
“It is vital that we all take action to protect our oceans
and we must act now before the scale of this problem heightens further. Simple
changes to everyday life are easy to do and give us the chance to prevent
further damage.
“We all use plastic but we have to think beyond ourselves
and save our beautiful and important seas. I’m pledging my support and hope
others will follow.”
