Rise in Ocean Plastics Evidenced in 60-Year Time Series

Scientists from the University of Plymouth and the Marine Biological Association have confirmed the significant increase in open-ocean plastics in recent decades using records of entanglement of plankton research equipment.

In a research paper published in the journal Nature Communications, the researchers present 60 years of data collected over 6.5 million nautical miles from the North Atlantic demonstrating a significant increase in larger plastic items such as bags, rope and netting (macroplastics) from 1957 to 2016.

The findings are based on records of when plastics have become entangled on a towed marine sampler, the Continuous Plankton Recorder. The device is towed in surface waters and occupies a similar space to a marine mammal. It is therefore impacted by entanglements in a similar way. It is towed off the back of ships-of-opportunity, such as ferries and container ships, at approximately seven meters depth and at 10–20 knots.

An increase in fishing related plastic entanglements, particularly in the North Sea region, contributed most significantly to the increase seen in macroplastic entanglements in the last two decades. More macroplastic entanglements occurred in high-density shipping route areas than areas of the open ocean such as the eastern North Atlantic.

The North Sea has large seabird and seal populations, as well as cetaceans, that are likely to have encountered plastic items and are at increasingly higher risk of entanglement, states the paper. “The use of ships-of-opportunity is an efficient (both in cost and time) way of covering vast areas, and should be utilized further to develop standardized and consistent strategies for monitoring plastic debris in the oceans.”
 
Contributing author Professor Richard Thompson, who leads the International Marine Litter Research Unit at the University of Plymouth, said: “It is perhaps no surprise that quantities of litter are increasing, but having robust evidence such as this is essential to help inform policy interventions on a global scale.”