Figure 2

Regional fisheries management organization (RFMO) registries, matched to AIS data, suggest that 0–61% of the key fleets vessels are not broadcasting AIS in each ocean basin. Flag states of fishing vessels with AIS in each region (a and c) and vessels registered to RFMOs (b, d, e). In the Indian Ocean region (a), vessels with AIS were present in five different exclusive economic zones (EEZs), while in the Pacific (c) All vessels were in the high seas. Of the fleets that were present in the Indian Ocean, when compared to the Indian Ocean Tuna Commission (IOTC) registry (b), fishing entity of Taiwan and Seychelles had a significant number of vessels on the registry that were not identified in AIS (gray bar), suggesting that these vessels may be operating without AIS, while the other fleets did not. The Pacific Ocean region spans two RFMOs (d, e), the Western and Central Pacific Fisheries Commission and the Inter-American Tropical Tuna Commission, and each fleet present has registered vessels that don’t appear in AIS (gray bars). The fraction of non-broadcasting fleets, according to registries, varies from 0% for Korean vessels in the Indian Ocean to 39% for vessels in the Indian Ocean from the Seychelles.