Tens of thousands of tonnes of plastic waste are floating in the North Pacific Ocean, forming a giant garbage island better known as the Great Pacific Garbage Patch.
The true origins of oceanic waste
A study by Dutch scientists shows that the island is mostly made up of abandoned nets and other fishing gear. All of these items have either been lost or simply dumped into the sea as rubbish.
The authors of the study claim that up to 86 per cent of the large pieces of plastic that make up this huge floating garbage dump come from Japanese, Taiwanese, American, South Korean and Chinese fishing vessels.
Redefining our understanding: from rivers to fishing boats
According to Matthias Egger, author of the study and a researcher at the Dutch non-profit organisation Ocean Cleanup, this new discovery should lead us to rethink the origins of the Pacific Northwest garbage island, and the knowledge gained by the Dutch researchers could help to better manage marine pollution in the future.
A sea of plastic
The polluted area was discovered in 1997 by the crew of a ship sailing from the Hawaiian archipelago to California. They noticed that a stretch of ocean far from human habitation was littered with plastic debris.
Plastic accumulates at the centre of ocean currents. The circular motion of the water pulls the debris towards the relatively calm centre, where it becomes trapped, forming a ‘garbage island’. Some researchers estimate that there are now more than 150 million tonnes of plastic there, with a further 8 million tonnes added every year.
A 2018 study found that almost half of the island’s rubbish was made up of fishing nets. The nets appeared to have come from fishing boats, but the research team was unable to determine the origin of the rest of the plastic at the time.
Tracing the origin of the debris
In 2019, Ocean Cleanup sampled more than 6,000 pieces of floating plastic from the island, weighing a total of 547 kilograms. Using the letters and logos printed on the plastic items, the researchers tried to identify the origin of the waste.
It turned out that about a third of the debris came from Japan – probably due to the tsunami that hit the country in 2011. The rest came from Taiwan, the United States, South Korea, mainland China, Hong Kong and Macau.
Notably, apart from China, no plastic was found from countries with heavily polluted rivers. According to Matthias Egger, this finding was unexpected, as rivers were previously thought to be the main source of marine plastic.
According to Egger, this suggests that plastic from inland areas tends to accumulate on the coast, while plastic dumped at sea is more likely to accumulate as litter in the ocean.
The results of the new study, combined with the knowledge that fishing gear makes up a significant proportion of the litter, suggest that the main source of litter in the North Pacific is the fishing sector in the five countries mentioned above.
The study has been published in the journal Scientific Reports.
Prepared by Mary Clair