AI and Satellites Expose Dark-Fleet Fishing in Sanctuaries

Global Fishing Watch combats illegal fishing in protected marine sanctuaries by combining satellite Automatic Identification System (AIS) data with behavioral artificial intelligence. By analyzing billions of GPS positions, their AI models learn to identify specific fishing activities based solely on vessel movement patterns. When combined with space-based radar and optical imagery, this technology exposes "dark fleets"—vessels that intentionally disable their transponders to fish illegally—allowing authorities to monitor marine sanctuaries and enforce conservation laws in real time.

Tracking Vessel Trajectories with AIS

Large commercial vessels are legally required to carry an Automatic Identification System (AIS) transponder. Originally designed to prevent collisions at sea, AIS continuously broadcasts a ship’s identity, GPS coordinates, speed, and course.

Satellites capture these broadcasts and send the data to Global Fishing Watch. By stringing together millions of individual data points over time, the organization reconstructs the exact trajectories of tens of thousands of vessels across the globe.

Identifying Fishing Behavior with AI

A vessel's trajectory reveals what it is doing. Global Fishing Watch uses machine learning algorithms trained on hundreds of thousands of hours of maritime data to classify vessel behavior. Different types of fishing create distinct movement patterns:

  • Longliners move in long, zig-zagging lines as they set and haul miles of baited hooks.
  • Purse seiners travel at high speeds and then make tight, repetitive circles to surround schools of fish with nets.
  • Trawlers move back and forth at slow, steady speeds while dragging heavy nets along the ocean floor.

The behavioral AI analyzes speed and turn angles to distinguish between a ship merely passing through a marine sanctuary—which is usually legal—and a ship actively fishing inside protected waters.

Exposing the "Dark Fleet"

Vessels engaging in illegal, unreported, and unregulated (IUU) fishing often turn off their AIS transponders before entering a marine sanctuary. These ships are known as the "dark fleet." Global Fishing Watch uses two primary methods to expose them:

  1. Intentional Disabling Detection: The AI monitors AIS signals that suddenly vanish near the borders of marine sanctuaries. It calculates the probability of whether the signal loss was due to poor satellite coverage or if the crew manually switched off the transponder to hide illegal activity.
  2. Satellite Radar Fusion: To find vessels that never broadcast AIS, the platform integrates Synthetic Aperture Radar (SAR) and optical imagery from satellites. SAR can penetrate clouds and darkness to bounce radar waves off the metal hulls of ships on the ocean surface.

The AI cross-references all ships physically detected by the radar against the database of active AIS broadcasts. Any ship appearing on the radar without a matching AIS signal is immediately flagged as a dark vessel.

Enforcing Marine Sanctuary Laws

Before this technology, patrolling vast, remote marine sanctuaries was nearly impossible for underfunded coast guards. Today, Global Fishing Watch provides this intelligence on a free, public map.

Enforcement agencies use these AI-generated insights to pinpoint illegal activities. Authorities can spot a dark vessel fishing in a sanctuary, track its movement back to port, and boarding teams can inspect the catch upon arrival, turning satellite data into direct legal action.