The northern part of the Pacific Ocean has been accumulating millions of tons of floating debris for decades. Plastic pollution reaches the ocean (it’s mostly plastics, but there’s also other synthetic debris) and gets caught in the current system of the North Pacific Ocean — this accumulation is called North Pacific Garbage Patch. Now, researchers tracked where this garbage is coming from.

The name is a bit misleading — it’s not exactly an island, but rather small bits of plastics (or microplastics). So it’s not exactly one uniform mass that can be seen with the naked eye, but a collection of various objects trapped by the currents. The seafloor beneath the garbage patch could also be an underwater trash heap, as 70% of the marine debris sinks to the bottom.

Several scientific teams have been analyzing the origin and characteristics of this waste in the garbage patch and, in parallel, implementing technology for its collection, as is the case of The Ocean CleanUp project. Now, working with researchers from Wageningen University, they have tracked down the country of origin of the waste.

Looking into the waste

The oceanographic mission on which the new study is based started in 2019 in the northern part of the Pacific and recovered more than 6,000 items of plastic debris larger than 5 centimeters in diameter. A third were unidentifiable objects, but two-thirds were objects used in the fishing industry, such as floats, buoys, crates, buckets, and baskets. In general, a striking proportion of ocean pollution comes from the fishing industry.

The debris was sorted, counted, weighed, and analyzed for evidence of origin and age. Nearly half (49%) of the plastic objects which could be dated were produced in the 20th century, with the oldest item being a buoy from 1966. This is in line with previous studies and shows the urgency to clean the garbage patch, the researchers highlighted.

“No matter what actions are taken to prevent riverine plastic emissions, the garbage patch will persist and its content will continue to beach on remote islands, such as the Hawaiian Archipelago, and fragment into microplastics that will eventually sink to the seabed,” Matthias Egger, an ocean scientist at Ocean CleanUp, wrote in a blog post.

In the study, they identified the country of origin of 232 objects, with most being from Japan at 34%. China ranked second (32%), followed by South Korea (9.9%), the US (6.5%), Taiwan (5.6%), and Canada (4.7%). Together, these six countries accounted for over 90% of the identifiable trash that was found in the North Pacific Garbage Patch.

It’s important to keep in mind that the great garbage patch may not be representative of the entire plastic pollution in the oceans. Still, this study could also highlight previous sources of plastic pollution that are less known. In fact most of these places are not recognized as major sources of riverine plastic emissions into the ocean, Egger explained. However, they are the ones that carry out most of the industrialized fishing activities in the North Pacific Garbage Patch. In fact, trash in the region was 10 times more likely to come from fishing activities than land-based ones. Globally, previous studies have estimated that around 20% of plastic pollution comes from the fishing industry.

The researchers said that improved fishing practices should be further embraced as a large part of the identified waste in the study was from the fishing industry. While it remains important to intercept riverine plastic and clean up the legacy plastic, the North Pacific Garbage Patch also requires addressing fishing activities, they said.

“Identifying the provenance of ocean plastic will also help formulate strategies and better inform states in addressing the ocean plastic pollution issue, including in the context of the ongoing negotiation of a new United Nations Plastics Treaty,” Egger wrote, referring to the expected new global treaty at the UN to tackle plastic waste.

The study was published in the journal Scientific Reports.