On World Oceans Day, Global Fishing Watch unmasks the global ‘dark fleet’


“Heatmap” of synthetic aperture radar returns (Global Fishing Watch)

Posted on June 8, 2022 at 11:57 p.m. by

The Maritime Executive







The AIS Global Fishing Watch tracking partnership has extended its reach with what it believes to be the first-ever publicly available global map of “undetected dark fleets” – vessels that do not broadcast AIS.


Using Synthetic Aperture Radar (SAR) data from the European Space Agency’s Sentinel-1 satellites, combined with machine learning algorithms, Global Fishing Watch discovered how to automatically track vessels without using AIS by satellite. By analyzing the entire Sentinel-1 radar image archive, Global Fishing Watch isolated 20 million data points showing the movements of ocean-going vessels about 30 feet in length. He compared these radar returns to 100 billion points of GPS position data from ships broadcasting their position via AIS. By correlating the two, the NGO’s system is able to track many ships even after they “go dark” and attempt to evade detection.


“It’s surprising how little we know about the true extent of human activity on the water,” said David Kroodsma, director of research and innovation at Global Fishing Watch. “If you combine vessels that intentionally cut off their signal with the significant number of vessels that do not make their location known to public systems at all, you end up with gaps in data, oversight and accountability. We use satellite radar imagery to reduce this information gap and bring our findings to those who want to ensure our ocean is managed equitably and sustainably.


The organization has previously used the technique to aid its investigations, such as the astonishing discovery of intensive Chinese fishing activity off the coast of North Korea – the largest known case of illegal fishing by an industrial fleet in the waters. from another country. The organization’s new public portal for SAR data is open to everyone, and it provides a radar-informed “heat map” for vessel presence and vessel fishing behavior. It does not allow the user to track individual vessels like publicly available AIS databases. For the researchers, however, the data stream from Sentinel-1 holds many possibilities – far beyond illegal fishing.


“By seeing and characterizing the activity of these vast dark fleets, we can begin to better understand and quantify not only illegal fishing, but much of the human activity that impacts our marine environment,” said said Paul Woods, director of innovation at Global Fishing. Look. “These are exciting times when it comes to open and accessible data that anyone can use for free to understand and defend the fragile marine areas that matter most to them.”





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