Researchers studying baby fish off the coast of Hawaii announced a troubling discovery on Monday.

Minuscule plastic particles are clustering at the oceans surface and mixing with critical sources of the hatchlings food. In these important feeding areas, plastics outnumber baby fish 7 to 1, researchers found. Some of the larval fish are eating these particles, which scientists believe could hurt their chances of survival and threaten the delicate food web that supports larger ocean creatures and humans.

We were shocked to find that so many of our [water] samples were dominated by plastics, Jonathan Whitney, who co-led the study, said in a press release.

The researchers didnt set out to report on plastics, said Whitney, a marine ecologist for the Joint Institute for Marine and Atmospheric Research in Honolulu. Rather, they intended to study the relatively unknown habits of baby fish across several species including swordfish, flying fish and mahi-mahi in their first days and weeks of life. But as he and his team began taking samples, trawling the ocean surface with a floating net, we were finding more plastics than fish, Whitney told HuffPost.

The study, published in the journal Proceedings of the National Academy of Sciences, focused on surface slicks near Hawaii Island. Slicks are slivers of ocean that can contain large amounts of plankton, a primary food source for larval fish. Wave convergences, ocean currents and variations in the seafloor herd plankton into the slicks, but these same forces also accumulate plastic particles. Slicks, which cover less than 10% of Hawaii Islands coastal waters, can contain a huge amount of larval fish, far more than surrounding waters. The slicks studied also had higher concentrations of plastics than other areas, the researchers found.

Most baby fish that feed in these floating buffets become bigger, faster and more developed than fish that grow up in surrounding waters, the researchers wrote. But the prevalence of plastic trash in the slicks might also create problems for growing fish.

The researchers found that the slicks contained roughly 40% more prey-sized plastics than surrounding waters. The team dissected 658 larval fish and noted 8.6% had ingested plastics, compared with only 3.7% from surrounding waters. Though the study noted more plankton than plastic both in the slicks and in ambient waters, the ratio of plastic to plankton was 60 times higher inside the slicks.

Its estimated that 8 million metric tons of plastics are dumped into the ocean every year, breaking into smaller pieces over time until theyre nearly invisible to the human eye. These particles, called microplastics , are less than 5 millimeters in size, not much bigger than plankton. Many of the plastic samples recovered in the Hawaii study came from industrial fishing equipment and single-use items like shopping bags and water bottles.