Photo/Illutration A dead leatherback turtle stranded on a beach in Mihama, Fukui Prefecture (Photo from the scientific paper)

A 1-square-meter plastic sheet was found inside a dead leatherback sea turtle on a beach in Fukui Prefecture, the largest piece of plastic debris reported ingested by the species, researchers said.

The male leatherback was found stranded on Kugushi beach in Mihama on Oct. 30, 2022, according to a research team comprising members mainly from the Fukui City Museum of Natural History.

The team’s findings were recently detailed in a scientific paper published in Marine Pollution Bulletin, a British journal on oceanic contamination.

According to the International Union for Conservation of Nature (IUCN), the leatherback sea turtle is vulnerable to extinction.

The creature was estimated to be a juvenile aged between 3 and 4 as its shell measured about 1 meter.

Adult leatherbacks can grow as large as nearly 2 meters long.

The species is the largest sea turtle that migrates in tropical and temperate seas, including the Pacific Ocean, the Atlantic Ocean and the Indian Ocean.

When the researchers examined the turtle at the Fukui museum, they found the plastic sheet measuring 106 centimeters by 118 cm and a PET bottle label, written in Japanese, stuck between its stomach and duodenum.

The findings showed that leatherbacks may accidentally ingest debris as large as themselves.

"I was fairly shocked to see the digestive tract fully stuffed with the compressed plastic materials," said Shota Deguchi, a curator at the museum.

Leatherbacks feed on jellyfish and other gelatinous creatures.

According to many reports, leatherbacks are accidentally ingesting white or transparent garbage.

The plastic sheet had small holes that appeared to be bite marks of the leatherback, indicating it mistook the waste for food.

However, the cause of death remains unclear.

In some cases, sea turtles die of starvation when plastic garbage obstructs their digestive tracts, making them unable to absorb nutrients.

But the leatherback was not skinny, suggesting it likely did not starve to death. It also had no noticeable external wounds.

“Because a piece of garbage with Japanese characters written on it came out, it can be said that leatherbacks are falling victim to garbage from Japan,” Deguchi said. “I hope it will serve as a starting point for people to think about marine debris as a problem close to them.”

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