British researchers have determined that plastic fishing gear, such as fishing nets and line, are the biggest source of plastic in the North Atlantic Ocean and nearby seas.

The research, led by Clare Ostle of the Marine Biological Association in the United Kingdom, is based off findings from the Continuous Plankton Recorder (CPR) a data instrument that has been towed in oceans for more than 12 million miles since 1957. Ostle notes that plastic fishing gear accounts for 55 percent of entanglements, with the higher number of entanglements in the southern North Sea. The research also shows a decline in entanglement records of plastic bags since 2000, but a 10-fold increase in total plastics.

“It has been suggested that there may be a sink of plastic items within global oceans, which could have led to reduced estimates of sea surface plastics and have implications for plastic pollution,” the researchers write in their paper, “The rise in ocean plastics evidenced from a 60-year time series,” which is published in the open access journal Nature Communications.

“Perhaps the reason we have been able to show the expected increase is because the focus of this work has been on larger plastic items that entangle on the CPR.

“It should be noted that these larger plastics (macroplastics) break down under ultra-violet light and mechanical forces within the ocean, leading to smaller fragments forming microplastics, therefore they have the potential to be a proxy for a wide-range of plastic sizes within the oceans.”

They say that the increase in macroplastics in the world’s oceans from 1957 to 2016 is in line with the total increase in plastic production.

The complete paper, with data figures, can be read on the Nature.com website.