The Great Pacific Garbage Patch is the world’s largest collection of floating trash—and the most famous. It lies between Hawaii and California and is often described as “larger than Texas,” even though it contains not a square foot of surface on which to stand. It cannot be seen from space, as is often claimed.

The lack of terra firma did not deter a pair of advertising executives from declaring the patch to be an actual place. They named it the nation of Trash Isles, signed up former Vice President Al Gore as its first “citizen” and last fall, petitioned the United Nations for recognition. The publicity stunt perpetuated the myth.

The patch was discovered in 1997 by Charles Moore, a yachtsman who had sailed through a mishmash of floating plastic bottles and other debris on his way home to Los Angeles. It was named by Curtis Ebbesmeyer, a Seattle oceanographer known for his expertise in tracking ocean currents and the movement of cargo lost overboard, including rubber duck bath toys and Nike tennis shoes. The patch is now the target of a $32 million cleanup campaign launched by a Dutch teenager, Boyan Slat, now 23, and head of the Ocean Cleanup, the organization he founded to do the job.

Beyond those details, not much was known about the specific contents of the patch—until now.

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What’s Really in the Patch?

Microplastics make up 94 percent of an estimated 1.8 trillion pieces of plastic in the patch. But that only amounts to eight percent of the total tonnage. As it turns out, of the 79,000 metric tons of plastic in the patch, most of it is abandoned fishing gear—not plastic bottles or packaging drawing headlines today.

A comprehensive new study by Slat’s team of scientists, published in Scientific Reports Thursday, concluded that the 79,000 tons was four to 16 times larger than has been previously estimated for the patch. The study also found that fishing nets account for 46 percent of the trash, with the majority of the rest composed of other fishing industry gear, including ropes, oyster spacers, eel traps, crates, and baskets. Scientists estimate that 20 percent of the debris is from the 2011 Japanese tsunami.

Laurent Lebreton, an oceanographer with the Ocean Cleanup and the study’s lead author, says the research team was looking to assess the larger pieces.

“I knew there would be a lot of fishing gear, but 46 percent was unexpectedly high,” he says. “Initially, we thought fishing gear would be more in the 20 percent range. That is the accepted number [for marine debris] globally—20 percent from fishing sources and 80 percent from land.”

Ghostnets, a term coined to describe purposely discarded or accidentally lost netting, drift through the ocean, entangling whales, seals, and turtles. An estimated 100,000 marine animals are strangled, suffocated, or injured by plastics every year.

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Ocean Cleanup is currently working on a system to remove much of this abandoned fishing gear, with plans to launch later this year.

“The interesting piece is that at least half of what they’re finding is not consumer plastics, which are central to much of the current debate, but fishing gear,” says George Leonard, the chief scientist at the Ocean Conservancy. “This study is confirmation that we know abandoned and lost gear is an important source of mortality for a whole host of animals and we need to broaden the plastic conversation to make sure we solve this wedge of the problem.”

Marine debris expert Marcus Eriksen, co-founder of the 5 Gyres Institute, cautions that the new study is based on only limited surveys, making it difficult to accurately estimate the complete size of the patch. The data are significant in showing such a high accumulation of fishing gear, he notes.

View Images This dead albatross chick was found with plastics in its stomach on Midway Atoll in the Northwestern Hawaiian Islands. Marine plastic can be dangerous to wildlife. Photograph by Dan Clark, USFWS/AP

A Sea of Plastic?

Publication of the garbage patch study coincided with a new report from Britain, Foresight Future of the Sea, that found plastic pollution in the ocean could triple by 2050 unless a “major response” is mounted to prevent plastic from reaching the ocean. The report declared plastic pollution to be one of the main environmental threats to the seas, along with sea-level rise and warming oceans.

The study included two aerial surveys in October of 2016 that took 7,000 images, and 652 ocean surface trawls conducted in July, August, and September of 2015 by 18 vessels.

The surface trawls also filled in the rest of the story.

Fifty plastic items collected had a readable production date: One from 1977, seven from the 1980s, 17 from the 1990s, 24 from the 2000s, and one from 2010. Researchers also found 386 objects with recognizable words or sentences in nine different languages.

The writing on a third of the objects was Japanese and another third was Chinese. The country of production was readable on 41 objects, showing they were manufactured in 12 different nations.

The study also concluded that plastic pollution is “increasing exponentially and at a faster rate than in surrounding waters.” Others are not as confident that the conclusion indicates a dramatic change in distribution of marine debris. Much of the world’s marine debris is believed to lie in the coastal regions, not in the middle of oceans.