Chinese fishing boats seen leaving the disputed waters of the Yellow Sea on 29 May 2009 following a threat of military action by North Korea
BYUN YEONG-WOOK/AFP via Getty Images
Satellite imaging has revealed hundreds of vessels from China fishing off the coast of North Korea, violating UN resolutions prohibiting such activity in the largest known case of vessels from one country operating unlawfully in another country’s waters.
More than 800 vessels were seen in 2019, say researchers at the non-profit Global Fishing Watch, who traced the boats to Chinese ports and waters. A similar number were seen in 2017 and 2018. They estimate that the vessels, about a third of China’s long-range fishing fleet, caught more than 160,000 tonnes of flying squid, rivalling the Japanese and South Korean total. Stocks of the squid, the main commercially fished species in the area, have declined dramatically in recent years.
“These novel insights are now possible thanks to advances in machine learning and the rapidly growing volume of high-resolution, high-frequency imagery that was unavailable even a couple of years ago,” says David Kroodsma at Global Fishing Watch. “We’ve shown we can track industrial fishing vessels that are not broadcasting their locations.”
All kinds of vessels are normally tracked by their Automatic Identification System (AIS) transponders, which can be detected by satellite. Boats fishing illegally often turn this off, but satellite-based radar can see all vessels and combining this with the AIS data can reveal which boats aren’t reporting their positions.
The team used satellite images to spot vessels both in the day and during the night, when fishing crews use floodlights to attract squid. They also used a machine learning system to scan images and pick out the distinctive technique of pair trawling, in which two vessels work together.
The study shows the pattern of illegal fishing activity but may not be able to catch individual criminals. Illegal fishing is generally carried out by boats with no official Chinese authority, no flag, and no registration papers, making them difficult to identify.
China’s Bureau of Fisheries didn’t respond to a request for comment. In response to allegations of illegal fishing in 2019, China told the UN it was already doing everything possible: “The competent Chinese authorities have prohibited ocean fishing operations in the DPRK (North Korean) sea areas (and) strengthened control and law enforcement”.
Journal reference: Science Advances, DOI: 10.1126/sciadv.abb1197
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