Ocean plastic increased 10-fold since 2000
British data finds fishing industry a major contributor to marine plastic pollution. Nick Carne reports.
British researchers have confirmed and quantified a significant rise this century in the amount of plastic floating in the North Atlantic Ocean and adjacent seas.
They found there has been a more than 10-fold increase since 2000 in the amount of plastic becoming entangled in the Continuous Plankton Recorder (CPR) – a sampling instrument that has been towed more than 12 million kilometres (6.5 million nautical miles) in the area since 1957.
Fishing gear, such as netting and line, is the main offender, accounting for 55% of entanglements. The highest levels of entanglement are in the southern North Sea.
At this stage the period 2010 to 2016 shows no significant change in total macroplastic counts compared to the 2000s, though the researchers say this cannot be confirmed until they have data for the whole of the current decade to ensure comparability.
Interestingly, they report evidence of a decline in the entanglement records of plastic bags since 2000 in the open ocean of the North Atlantic.
Overall, their consistent time series “provides some of the earliest records of plastic entanglement, and is the first to confirm a significant increase in open ocean plastics in recent decades,” they write in a paper published in the journal Nature Communications.
The few existing historical records of oceanic plastic occurrence are mainly linked to ingestion studies of seabirds and sea turtles.
The new research was led by Clare Ostle from the Marine Biological Association in Plymouth, UK.
The researchers say the observed increase in macroplastics from 1957 to 2016 is in line with the exponential increase in total plastic production worldwide.
“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,” they write.
“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.”
The data shows that macroplastic debris is found throughout the North Atlantic, though perhaps not surprisingly, more entanglements occur in high-density shipping route areas.