The tool uses AIS data from fishing vessels and tenders, and it focuses on ports with the highest number of visits from foreign-flagged fishing vessels.

Pew reports that IUU fishing could be reduced through stronger controls at ports, and the new tool is designed to help by showing which port states are most likely to receive vessels carrying IUU-caught fish. The tool also shows which ports and states are busiest, making it a way to examine activity patterns of fishing vessels.

The tool suggests that Zhoushan, China has by far the most port calls by AIS-enabled fishing vessels, followed by other Chinese ports.

In addition, the tool suggests that Bangkok had only 28 fishing boat port calls for all of 2017, a potential reflection of the Thai fleet's AIS use patterns.

To remind, in 2016, the United Nations Food and Agriculture Organization Agreement on Port State Measures (PSMA) entered into force, helping to combat illegal fishing by requiring parties to place tighter controls on foreign-flagged vessels seeking to enter and use their ports. Today, 66 countries and the EU are party to the treaty.