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By 2009, the tide had shifted, with Asia surpassing South America in the amount of plastic load washed up on the island. In 2018, 73 per cent of the plastic bottles collected came from Asia, with 83 per cent from China.

“What was really shocking was how the origin had shifted from largely South American, which is what you would expect from somewhere like Inaccessible Island because it’s downwind from South America to predominantly Asian,” Ryan added.

Furthermore, 90 percent of the bottles that travelled from Asia were date-stamped within the last two years — ruling out the possibility that they could have travelled from land via ocean currents, which would take between three to five years.

“My initial thought was that it was going to be fishing fleets,” Ryan told BBC. “Fishing boats tend to be a little bit more Wild West than the merchant fleets as a rule, but the fact that it’s primarily Chinese doesn’t really fit with that because the predominant fishing fleets in the South Atlantic are Taiwanese and Japanese,” he added.

Researchers found that while the number of Asian fishing vessels in the South Atlantic have remained stable, the number of cargo vessels — namely, Chinese — had increased since the 1980s, which narrowed down merchant vessels as the primary source.

“I think the evidence is pretty strong that it’s coming from merchant shipping,” he said, adding that he was initially surprised by results since he assumed that the merchant ships would be tied by theInternational Convention for the Prevention of Pollution from Ships regulations. “I think we need to look quite carefully at better monitoring and enforcement of regulations,” he said.

One of the study authors, Robert A. Ronconib is affiliated with the Canadian Wildlife Service, Environment and Climate Change Canada, Dartmouth, NS B2Y 2N6, Canada.