About ten years ago, the Great Pacific Garbage Patch entered the American imagination as a swirling island of trash floating atop the ocean. In reality, the garbage patch is almost invisible, though it contains some 1.8 trillion pieces of plastic weighing 88,000 tons.
Now, new research finds that baby fish off the coast of Hawaii congregate in waters filled with concentrations of plastic eight times higher than the Great Pacific Garbage Patch, and they’re mistaking the trash for food. In these nurseries, the larval fish, including species like swordfish and mahi mahi, are outnumbered by microscopic plastics seven to one.
The findings identify another way plastic is entering the ocean food chain, and raise disturbing questions about the impact the petroleum products may be having on fish populations.
“It is alarming that larval fish are surrounded by and ingesting non-nutritious toxin-laden plastics at their most vulnerable life-history stage when nutrition is vital for survival,” said Jamison Gove, an oceanographer for the National Oceanic and Atmospheric Administration (NOAA) who worked on the study.
The researchers didn’t set out to discover the plastic buffet lurking in these marine nurseries. Instead, they were trying to find out out how baby fish used meandering ribbons of smooth water on the ocean surface called “slicks.” The wind and currents that form slicks also collect an abundance of the tiny food particles fish larvae need to survive.
But when the researchers started dragging nets with super-fine mesh through slicks off the coast of Hawaii, plastic took over their study. Inside the slicks they found concentrations of plastic 126 times higher than the surrounding waters.
“We were shocked to find that so many of our samples were dominated by plastics,” said Jonathan Whitney, a marine ecologist at NOAA and study co-author.
With the study officially hijacked by pollution, the researchers dissected hundreds of the tiny fish and found their minuscule stomachs stuffed with plastics. The newborn swimmers were a diverse bunch, with species hailing from coral reefs, the open ocean and even the deep sea.
The study didn’t investigate the impact of all this plastic winding up in baby fish, but researchers say it can’t be good. Eating plastics can harm adult fish by filling their stomachs with indigestible material, causing malnutrition, and by leaching toxins that can disrupt biological processes like hormone signaling. At the larval stage fish are even smaller and more delicate, suggesting these same problems could be magnified.
“Biodiversity and fisheries production are currently threatened by a variety of human-induced stressors such as climate change, habitat loss, and overfishing,” said Gove.
“Unfortunately, our research suggests we can likely now add plastic ingestion by larval fish to that list of threats.”
(Some video imagery courtesy of PNAS)
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