It's estimated that close to 300 million tons of plastic are produced every year, more than half of which is for single-use products. Those discarded plastic bottles, bags, straws and other plastic waste end up largely in our oceans, to the tune of more than 8 million tons a year.1 Carried along with the ocean's currents, swirling gyres of "plastic smog"2 now cover about 40 percent of the world's ocean surfaces.3
While these heavily plastic polluted areas are often referred to as garbage patches in the sea, the problem is not limited to large debris. Perhaps even worse, it's estimated that 15 trillion to 51 trillion pieces of plastic are now in the ocean, reaching as far as the Arctic. Once broken down by the elements, the plastic will turn into microplastic particles, which are less than 5 millimeters long. To understand the extent of the pollution, the United Nations Environment Program described 51 trillion as "500 times more than the stars in our galaxy."4
According to Marcus Eriksen, a co-founder of the conservation group 5 Gyres, in the Huffington Post, "[I]f you were to stand on the bottom of the ocean in the middle of a gyre and look up, the water overhead wouldn't look clear … What you'd see are these massive clouds. Clouds of micro- and nanoplastics stuck in the ocean's gyres."
Fish Are Actively Seeking Out Tiny Plastic Particles as Food
The tiny plastic particles filling up our oceans are not without consequence. It's long been known that various forms of marine life are ingesting the plastic, but this was thought to be an accident, or perhaps that they were drawn in by an aspect of its appearance. New research suggests, however, that fish may be actively seeking out the plastic particles, mistaking them for food because of their odor.5
When microplastics exist in the ocean, they form a biological covering made of algae and other materials that smell like the food the fish would normally eat. The study is the first to reveal not only that anchovy use odors to forage, but also that the odor of microplastic in the ocean induces foraging behaviors in schools of the fish. Study author Matthew Savoca, of the National Oceanic and Atmospheric Administration, told the Guardian:6
"When plastic floats at sea its surface gets colonized by algae within days or weeks, a process known as biofouling. Previous research has shown that this algae produces and emits DMS, an algal based compound that certain marine animals use to find food. [The research shows] plastic may be more deceptive to fish than previously thought. If plastic both looks and smells like food, it is more difficult for animals like fish to distinguish it as not food."
More than 50 species of fish are known to ingest plastic debris, according to the researchers, who noted that the plastic can cause lethal and sublethal problems in fish as well as serve as a "route for bioaccumulation of toxic compounds throughout the food web."7 Ingestion of micro- and nanoplastics by fish has been linked to intestinal blockage, physical damage, alterations in the intestines, change in behavior, change in lipid metabolism, transfer to the liver and more.8
Previous research has also shown that foraging seabirds are attracted to microplastics because of their smell. “Marine-seasoned microplastics produce a dimethyl sulfide (DMS) signature [the smell of algae] … creating an olfactory trap for susceptible marine wildlife,” the researchers noted.9,10
How Much Plastic Are Fish Eating?
The Center for Biological Diversity noted that fish in the North Pacific are known to ingest 12,000 to 24,000 tons of plastic every year and, in a study of fish markets in California and Indonesia, one-quarter of the fish were found to have plastics in their guts.11 Plastics and other man-made debris was also found in 33 percent of shellfish sampled.12
Writing in the journal Integrated Environmental Assessment and Management, researchers noted, "The potential for humans, as top predators, to consume microplastics as contaminants in seafood is very real, and its implications for health need to be considered."13 Savoca also noted that "our consume-and-dispose culture is coming back to haunt us via the fish we eat," and the next step will be to determine whether toxins accumulated in the plastic are transferring to the flesh of the fish and, thereby, to the humans who eat it.14
One 2014 study also found microplastics in oysters and mussels being sold at supermarkets. As a result, and since people ingest the entire oyster or muscle body, plastics in the gut and all, the researchers suggested that the average European who eats shellfish may consume 11,000 microplastics per year.15 That number is only likely to get worse if predictions by the World Economic Forum come true; they estimated that if waste-management practices don't change, there could be more plastic in the oceans than fish by 2050.16
Also disturbing, in a study of freshwater environments, 83 percent of the fish had plastic debris in their gut, mostly microplastics, particularly microfibers.17 The fish appeared to consume more microplastics near urbanized sections of the river and when fish ate a lot of the plastics, they appeared to eat a less diverse variety of other food items. So it's not only marine life in the oceans that are being harmed by plastic debris; freshwater creatures are also at risk.