The researchers also fished out a ’90s-era Game Boy cover, construction-site helmets and a toilet seat, as well as a number of objects with Japanese and Chinese inscriptions. Other objects, Mr. Lebreton said, had “little bite marks from fish.”

Some sea turtles caught near the patch were eating so much plastic that it made up around three-quarters of their diet, according to the foundation.

The garbage patch is not exactly a “patch”

After its discovery in the late ’90s, the Great Pacific Garbage Patch took on an image in the popular imagination akin to an island or even a seventh continent made of trash. That myth was debunked, and the patch became understood as more like a region that looked like the rest of the ocean to the naked eye, but was polluted with tiny microplastics.

However the new study says that the microplastics, while still a problem, account for just 8 percent of the mass of the patch. Until now, most of the sampling used an ocean trawl designed to pick up small particles, and therefore, Mr. Lebreton said, underestimated the number of larger pieces of debris floating in the sea, like bottles, buoys and fishing nets.

“Most of the mass is actually large debris, ready to decompose into microplastic,” Mr. Lebreton said.

Still, “it’s not an island,” Mr. Lebreton said. “It’s very scattered.” (A visual model, however, shows how the debris is condensed in one area in the ocean.)