Related expert: We can’t manage what we can’t see.
For decades, industrial fishing has operated in the shadows, remaining one of the most opaque and unmonitored sectors in global commerce. Global Fishing Watch’s mission is to shine a light on human activity at sea, bringing transparency to global fisheries and strengthening ocean governance.
What is vessel tracking?
Vessel tracking is a critical tool for sustainable fisheries management and a fundamental principle of transparency — the act of making specific ocean and vessel data, as well as the policies and decisions that surround them, both available and accessible to those that need it. By harnessing satellite technology, tracking systems like the automatic identification system (AIS) and vessel monitoring system (VMS), are able to record ship positions, identities and movements. These platforms provide valuable information about a given vessel and its whereabouts, helping create a more comprehensive picture of what is happening at sea.
From data to accountability
The lack of a standardized, well-regulated vessel tracking framework creates a systemic failure in ocean governance that extends far beyond the water’s surface. While vessel tracking can be a powerful tool in the fight against illegal, unreported and unregulated (IUU) fishing, the absence of uniform regulations severely undermines fisheries management. This regulatory gap limits due diligence in supply chains, threatens marine biodiversity and compromises fisher safety.
Global Fishing Watch’s suite of monitoring tools — including its flagship map — empowers stakeholders to track vessel behavior, analyze ocean conditions and strengthen due diligence. The platform processes and visualizes data from continuous data streams of vessel positions and satellite imagery so users can see current activity as well as historical trends dating back to 2012.
By combining vessel tracking data with satellite detections of vessels that are not broadcasting their positions, we can map both tracked and “dark” vessels at sea — those that do not appear in public monitoring systems. This fuller picture of maritime activity helps authorities respond to suspicious activity and fuels long-term analysis of how fishing patterns and ocean use evolve over time.
Key benefits of vessel tracking
By making the invisible visible, vessel tracking serves as a cornerstone for effective ocean governance, empowering governments to protect marine ecosystems, support artisanal fishers and ensure long-term food security. Key benefits of vessel tracking include:
Enhanced monitoring, control and surveillance: Vessel tracking allows authorities to continually monitor fishing activities and rapidly detect suspicious behavior at sea.
Stronger enforcement: By exposing noncompliant vessels, tracking provides authorities with the evidence required to take swift and decisive enforcement actions.
Increased safety: By keeping a constant eye on vessel movements, tracking technology ensures authorities can deploy faster, more precise operations during life-threatening emergencies at sea.
Supply chain transparency: By verifying where and how seafood is caught, vessel tracking data empowers companies to meet traceability standards and commit to responsible sourcing.
Biodiversity protection: By detecting unauthorized human activity — including IUU fishing — vessel tracking supports the robust monitoring and enforcement of marine protected areas (MPAs) to safeguard ecosystems and habitats.
Vessel tracking technologies
To safeguard our ocean and its resources, governments and international fisheries bodies are increasingly recognizing the importance of transparency and vessel tracking in effective fisheries governance. While VMS remains the primary fisheries compliance tool used by governments for tracking vessels, complementary systems such as AIS provide a more complete and accessible picture of vessel activity.
Global Fishing Watch supports governments and partners in the adoption and advancement of both technologies. Used together, AIS and VMS create a more comprehensive view of global fishing activity and strengthen monitoring, control and surveillance efforts.
AIS and VMS: Complementary tools for effective vessel tracking
| Vessel Tracking Technologies | AIS | VMS |
|---|---|---|
| Primary purpose | A maritime safety tool — designed for collision avoidance and vessel traffic monitoring. | A fisheries compliance tool — designed for MCS enforcement and resource management. |
| Primary function | Broadcasts vessel identity, position, speed, and course in near real time. | Transmits vessel location data at set intervals to fisheries authorities. |
| Transmission and accessibility | Openly transmitted signals are captured by satellite, land or vessel receivers and then aggregated by commercial providers. Positions are recorded across all flag States and jurisdictions, allowing monitoring of national and foreign vessels. | A closed, secure system transmitting fleet data directly to national monitoring centers. Remains private to that nation or region unless publicly shared by the government. |
| Regulatory requirements | AIS requirements for vessels vary widely and are often dependent on vessel size. | Mandated by fisheries authorities for vessels, depending on gear, region or size — typically required for vessels over 12 meters. |
IMO numbers: The identity layer of vessel tracking
Effective fisheries governance depends on reliable vessel identification. While a ship’s name can be repainted or its flag changed overnight, an International Maritime Organization (IMO) number remains permanently tied to a vessel. Because IMO numbers are transmitted through vessel tracking systems such as AIS, they allow satellite tracking data to be linked to a persistent and verifiable identity.
While the legal basis for vessel identification is anchored in the International Convention for the Safety of Life at Sea (SOLAS), the IMO number functions as the critical technical identifier. It allows satellite tracking data to be linked to a verifiable identity, creating a continuous record of a vessel’s history, ownership and behavior across jurisdictions. By bridging the gap between moving dots on a map and legal accountability, IMO numbers turn raw data into a powerful tool for enforcing regulations, securing supply chains and protecting the long-term health of our ocean.
The transparency gap: Mapping the unseen
A landmark 2024 Global Fishing Watch study published in Nature revealed a startling reality: approximately 75 percent of the world’s industrial fishing vessels are not tracked by public monitoring systems. While non-transmitting vessels can be seen in some satellite images, the lack of vessel position and identity data can hide them from authorities and regulators. This gap in knowledge can leave authorities without the adequate information needed to enforce regulations and hinders decision makers from establishing informed, responsible policies that bolster governance and promote sustainability.
©2024 Global Fishing Watch
Toward an international mandate on vessel tracking
Globally, there is still no universal requirement for fishing vessels to use tracking systems or broadcast their data. This patchwork of rules varies significantly across regions, flag States and fisheries. The resulting fragmentation creates critical blind spots that bad actors can exploit, leaving fisheries managers and authorities in the dark.
A stronger transparency-based vessel tracking framework would improve accountability by making compliance easier to verify and enforcement more effective. Global Fishing Watch supports efforts to advance a new international instrument on vessel tracking aimed at closing transparency gaps and improving ocean fisheries management worldwide.
