How researchers are tracking illegal ghost boats and the decline in flying squid

An international group of researchers used a new combination of satellite imagery to track the scale of illegal fishing by Chinese-based vessels.

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Just a few short years ago, researcher Jaeyoon Park said there was frequently one thing on the menu in his aunt’s coastal Korean village: cheap, plentiful squid.

Now, that bounty is over, he says.

“It’s become three to four times the price it was a couple years ago,” he says. “People call it ‘golden squid’ now.”

The disappearance of east Asia’s flying squid population—which has declined by 80% over the past 15 years—has continued despite efforts by Japan and South Korea to manage the catch sustainably. In the process, it has destroyed local livelihoods, changed diets, and produced a dark legacy of “ghost boats” washing up on Japanese shores.

Now, an international group of researchers, including Park, a data scientist at the NGO Global Fishing Watch, say they have tracked the source: an army of untracked, so-called “dark” fishing vessels, that leave Chinese ports to fish illegally off the coast of North Korea. The research, published in Science Advances on Wednesday, is also a case study for a new method of using satellite-based tracking technologies that the researchers say will make it possible to track shadowy activity on the world’s oceans—from overfishing to sand mining—like never before.

The study, Illuminating Dark Fishing Fleets in North Korea, was conducted as a partnership between Global Fishing Watch and SkyTruth—two NGOs which use satellite technology to track fisheries and environmental exploitation—with researchers at Duke University, the Japan Fisheries Research and Education Agency, the Australian National Centre for Ocean Resources and Security, the Korea Maritime Institute, Planet Labs, and the University of California at Santa Cruz.

While illegal fishing isn’t unique to North Korea, the broader region’s extreme geopolitical tension and lack of co-operation make the country’s coasts “one of the least monitored regions in the world,” says Park, where illegal activity can flourish, unwatched.

The choice to go with the “worst test case” possible, in North Korea, will demonstrate that it’s finally possible to comprehensively track the movement of vessels around the world, whether they’re involved in sanctions busting, overfishing, or trafficking, Park said.

Because of international sanctions against North Korea, which make fishing or buying seafood from the country illegal, the vast majority of boats in the region go “dark”, or turn off their AIS, a universal vessel-tracking system based on GPS, when entering territorial waters. The region is also home to endemic GPS jamming and spoofing, methods of disrupting or confusing GPS receivers, therefore making vessels harder to track.

“When we look at the AIS map, there’s a big hole,” says Park. “That’s quite suspicious.”

In order to create a map of fishing in the region, the team combined four satellite tracking methods for the first time: AIS, alongside Satellite Synthetic Aperture Radar (SAR), which can identify metal vessels; the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor, which can regularly detect vessels with bright lights—including the lights used at night by squid fishing boats to attract the squid—and high-resolution optical imagery. Collectively, those methods made it possible to map vessels over time, even through cloud cover, which has previously made tracking difficult.

Illegal activity at sea has long been difficult to track and enforce. Even with tracking measures, Park admits that finding the owners or operators behind vessels is difficult. Even if it’s possible to find a vessel’s name or tracking number, a vast system enables owners to operate in secrecy: vessels can be registered in countries with lax oversight, while Russian Doll-style systems of shell companies allow even vessels on international sanctions lists to quickly appear to change ownership.

It’s a “big headache,” said Park. “Not just for us, but for everyone, to find out who’s behind these vessels.”

The North Korean study followed anecdotal reports from governments that overfishing, paired with climate change that has warmed the region’s waters, was likely the source of a decline in squid populations so severe that many Japanese fishermen simply no longer bother to fish for them. Yet squid is extremely popular: in South Korea, it is the country’s top seafood by production value, and it is in the top five in Japan.

The study estimated that the catch by vessels in North Korean waters collectively outstripped the combined annual catch of both Japan and South Korea. In 2017, trawlers off the coast of North Korea caught an estimated 101,300 metric tons of squid, worth $275 million; the next year, an estimated 588 vessels caught squid worth $171 million, making the haul the largest known case of illegal fishing by vessels from distant waters in the world.

Due to a lack of transparency, it’s impossible to say exactly how much of the total squid consumption in the region is the result of illegal fishing, or how much of that reaches the United States, where regional varieties of squid are available. However, the Monterey Bay Aquarium’s Seafood Watch project advises against eating flying squid from the region, citing declining stocks and suspected overfishing.

The rates of illegal fishing also have dire consequences for North Korean fishermen, who have been pushed by competition from the Chinese boats to move north, fishing illegally off the far eastern coast of Russia. Pre-sanctions, squid was North Korea’s third largest export.

However, unlike the well-equipped fishing boats from Chinese ports, the North Korean boats are small, wooden fishing vessels that are unequipped to travel the hundreds of kilometers into Russian waters, the study said. That dangerous journey has produced evidence of a humanitarian crisis. In 2018 alone, 225 so called “ghost boats”, some containing the bodies of fishermen who starved to death onboard, were found washed up on Japanese coasts.

The study is a grim reminder of the scale of commerce taking place in the shadows on the world’s oceans, and the knock-on effects of the race for resources when regional and international co-operation and transparency is lacking.

The next step will be whether regional governments can find a way to enforce or intervene to limit the sheer scale of the illegal fishing.

“This is the beginning of the story, probably,” said Park. “What we provide is underlying information and data.”

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