Illuminating dark fishing fleets in North Korea

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Science Advances  22 Jul 2020:
Vol. 6, no. 30, eabb1197
DOI: 10.1126/sciadv.abb1197
  • Fig. 1 Activity of pair trawlers originating from China in North Korean waters.

    (A) Pair trawler of Chinese origin on its way to North Korean waters (photographed by the South Korean authorities). (B) A satellite image of the pair trawler fleet operating in North Korea (PlanetScope, 3-m resolution). Gray ovals show where the neural net classifier identified pair trawlers. In this area, we received AIS messages from several vessels (only two are shown). White lines connect their most recent AIS position to the estimated position during the time of the satellite image based on extrapolating the vessel’s speed and course. In white is the 9-digit Maritime Mobile Service Identity (MMSI) of each. (C) Higher-resolution image of pair trawlers in operation in North Korea (SkySat, 0.72 m). (D) AIS tracks for one of the two vessels matched to (B), showing the vessel originating from Shandong province, China. (E) Pair trawlers across our study area identified by the convolutional neural network (CNN) classifier and optical imagery. Each Planet image (24 km by 7 km) is a gray rectangle on the map, with 447 total images for this day. Light purple box shows the location of the main fleet. (F) Pair trawlers identified through another technology, SAR, by counting vessels within 535 m of one another.

  • Fig. 2 Origin of vessels fishing in North Korean waters.

    During 2017 and 2018, vessels that fished in North Korean waters originated from Chinese ports and also fished in Chinese waters. Included are all AIS positions broadcast by all vessels identified as likely fishing within the claimed North Korean EEZ. Each position was identified as fishing or nonfishing by the model described in (16).

  • Fig. 3 Chinese and North Korean lighting vessels.

    (A) A 55- to 60-m Chinese lighting vessel near North Korean waters. (B) A Planet SkySat (0.72-m resolution) image of a Chinese lighting vessel. (C) A 10- to 20-m wooden North Korean lighting vessel in the Russian EEZ. (D) Vessel detections on 24 October 2017 by SAR, which detects large, metallic vessels but not smaller wooden ones [by PALSAR-2 (Phased Array L-band Synthetic Aperture Radar-2); blue box shows detection footprint, and blue dots show vessels]; and by VIIRS, 2 hours later, revealing lighting vessels with the brightest lights (red, >1000 nW/cm2/sr, mostly Chinese), with medium lights (orange, 50 to 1000 nW/cm2/sr, South Korean or Chinese), and the dimmest lights (yellow, <50 nW/cm2/sr, mostly North Korean). Vessels in (D) (i) are Chinese lighting vessels, (ii) Chinese pair trawlers (detected only by SAR), (iii) North Korean squid vessels (detected only by VIIRS), and (iv) the South Korean squid fleet.

  • Fig. 4 Satellites track fishing by Chinese and North Korean vessels.

    (A) Counts of Chinese pair trawlers and (B) lighting vessels operating in our study area during 2017 and 2018. Because of weather conditions or incomplete coverage of the study area [e.g., Sentinel-1 footprint covers <1/2 of the study area (fig. S9)], vessel counts are mostly underestimates, so we use the maximum value over a half-month period to estimate the number of active vessels, which is shown by the gray bars. (C) Estimated total number of Chinese vessels operating in each half month (gray bars) is largely consistent with the counts of vessels from the South Korean Coast Guard (black line). (D) Estimated number of North Korean lighting vessels operating in the Russian EEZ, 2015–2018; data for each half-month period are the maximum number of VIIRS detections below 50 nW/cm2/sr.

Supplementary Materials

  • Supplementary Materials

    Illuminating dark fishing fleets in North Korea

    Jaeyoon Park, Jungsam Lee, Katherine Seto, Timothy Hochberg, Brian A. Wong, Nathan A. Miller, Kenji Takasaki, Hiroshi Kubota, Yoshioki Oozeki, Sejal Doshi, Maya Midzik, Quentin Hanich, Brian Sullivan, Paul Woods, David A. Kroodsma

    Download Supplement

    The PDF file includes:

    • Supplementary Materials and Methods
    • Sections S1 to S9
    • Figs. S1 to S27
    • Tables S1 to S6
    • Legends for movies S1 to S3
    • References

    Other Supplementary Material for this manuscript includes the following:

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