Satellite synthetic aperture radar (SAR) can identify all large metal vessels and penetrate clouds but lacks regular, global coverage of the oceans ( 17). Automatic Identification Systems (AIS) provide detailed movement and identity information but are used by only a fraction of vessels ( 16). Individual technologies have distinct limitations but, when combined, can provide an informative picture of fishing activity (table S1). Here, to illuminate the activities of dark fleets in one of the most contested regions of the world’s ocean, we combine local expertise with four satellite technologies. Evidence of continued Chinese fishing in North Korean waters is also supported by domestic Chinese documentation ( 13).

Despite this, the South Korean Coast Guard has observed hundreds of vessels crossing into North Korean waters, and random inspections of these vessels by the East Sea Fisheries Management Service suggest that they are of Chinese origin ( 13). Because sanctions under Chapter VII of the UN Charter are binding and implemented via domestic law and policy, any violations of these sanctions by Chinese vessels since September 2017 would constitute a violation of public international law and domestic Chinese law ( 13– 15). These resolutions prohibit (i) the procurement of seafood from North Korea, (ii) joint ventures between North Korea and other countries without UN approval, and (iii) North Korea from selling or transferring fishing rights ( 13). In 2017, following North Korea’s testing of ballistic missiles, the United Nations (UN) Security Council adopted resolutions to sanction the country, restricting foreign fishing after September 2017. pacificus is South Korea’s top seafood by production value ( 9), one of the top 5 seafoods consumed in Japan ( 11), and, until recent sanctions, was the third largest North Korean export ( 12). This inability to assess the stock is concerning considering the critical importance of squid in the region. This lack of information sharing prevents accurate stock assessment in a fishery where reported catches have dropped by 80 and 82% in South Korean and Japanese waters, respectively, since 2003 ( 9, 10). Although the Chinese fleet has fished in North Korean waters since 2004, its fishing activity and catches are only intermittently published, and not since 2016 (table S6). In these poorly observed waters, the same stocks of Todarodes pacificus (Japanese flying squid) are targeted by several fleets, including the Chinese distant-water fleet ( 7, 8). These challenges with dark fleets and IUU fishing are epitomized in the waters between North Korea, South Korea, Japan, and Russia, where geopolitical tensions and disputed boundaries create a vacuum of shared data and management ( 6).

Lee illuminate