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article imageNew study shows vast scope of our exploitation of the ocean

By Karen Graham     Feb 23, 2018 in Science
Monitoring the global fishing industry has been difficult, and this means visualizing its global footprint has been almost impossible. Much of the fishing is unobserved, taking place far from land, with boats leaving little trace of their activity.
But this week, a new study published in the journal Science helped to fill in the gaps with some amazing maps. The researchers were able to document just how far global fishing fleets will travel — covering more than 460 million kilometers (285,830,748 miles) in 2016 — a distance equal to going to the moon and back 600 times, reports CTV News .
The data and analysis presented in the study is the result of a collaboration between SkyTruth, Global Fishing Watch, the National Geographic Society's Pristine Seas project, Google and universities in the United States and Canada. The research was led by David Kroodsma, a research program manager at Global Fishing Watch.
Global Fishing Watch
The researchers were able to track the world's fishing vessels through an entire year by using satellite feeds to monitor the vessels' automatic identification system (AIS) that most vessels now emit automatically in order to avoid collisions with each other. This data collecting was central to the study.
The study looked at 22 billion global AIS positions from 2012 to 2016. They point out the figures represent a small proportion of the world's estimated 2.9 million motorized fishing vessels.
Global Fishing Watch now monitors over 70,000 fishing vessels. Machine learning was used to classify the tracks of these vessels and infer both where they were fishing and what type of fishing gear they were likely using. Based on vessel movements, models could even predict vessel characteristics like length and engine power.
This map shows fishing by trawlers  which drag fishing nets behind them. They dominate fishing in co...
This map shows fishing by trawlers, which drag fishing nets behind them. They dominate fishing in coastal areas, such as fisheries near Europe and China.
Global Fishing Watch
The research came up with some interesting facts that reflect on demographics and even nationalities. But one thing is definitely true: commercial fishing today covers more than half of the world's ocean surfaces. "Our data show that industrial fishing occurs in 55 percent of ocean area and has a spatial extent more than four times that of agriculture," the study says.
The maps show intensive fishing occurring along the coasts of heavily populated areas, like Europe and China. Surprisingly, fishermen in North America appeared to take most weekends off, while in China, the only time the fishing fleets were idle was during the Chinese New Year, or during the summer fishing moratorium.
Perhaps more important was the ability of the researchers to distinguish the vessels belonging to different countries. According to the study, five countries — China, Spain, Taiwan, Japan and South Korea — accounted for 85 percent of all high-seas fishing, reports National Public Radio.
This map shows activity of fishing vessels that use drifting longlines. They roamed the high seas  e...
This map shows activity of fishing vessels that use drifting longlines. They roamed the high seas, especially in tropical latitudes.
Global Fishing Watch
"I've been working on fishing for 20 years and it totally blows me away," co-author Boris Worm, a marine biologist at Dalhousie University in Halifax, said of the findings. "The fundamental problem with fishing is the lack of oversight particularly on the high seas," Worm said. "Now we have that oversight -- we can see it from space."
David Kroodsma said the main purpose of the study was to provide transparency to the fishing industry, which has had very little in the past. "For me what's most exciting is not just this dataset but what comes next. There are all of these questions about how we fish in the ocean that we can now answer that we could not before," he said.
The study, Tracking the global footprint of fisheries, was published in the journal Science on February 23, 2017.
More about ocean fisheries, Exploitation, global footprint, economic zones, Sustainability