Earth's oceans are filled with what scientists are calling "dark vessels"

A recent study by Global Fishing Watch has uncovered an immense quantity of previously untracked vessel activity at sea.

The ocean has long been a vast and mysterious frontier, covering over 70% of the Earth’s surface. It is the lifeblood of global trade, a crucial source of food, and a key player in energy production. Yet, despite its importance, much of what happens on its surface remains shrouded in secrecy.

By leveraging satellite imagery, vessel GPS data, and artificial intelligence, researchers have created a detailed map of industrial vessel movements and offshore energy infrastructure.

The findings reveal staggering gaps in public tracking systems, raising urgent concerns about maritime transparency, environmental sustainability, and global security.

Dark vessels at sea

For years, maritime organizations and governments have relied on the Automatic Identification System (AIS) to track vessel movements. While AIS is useful for monitoring registered ships, it has significant limitations.

Not all countries mandate its use, and many vessels turn off their transponders to avoid detection, particularly those engaging in illegal fishing, smuggling, and other illicit activities.

The experts found that between 72% and 76% of the world’s industrial fishing vessels are not publicly tracked – a striking figure that highlights the hidden scale of commercial fishing operations.

Even more concerning, 21% to 30% of transport and energy vessel activity is missing from public monitoring systems, further obscuring the true scale of industrial use of the ocean.

Hidden fishing activity

Most of this untracked activity occurs in South Asia, Southeast Asia, and the northern and western coasts of Africa. These regions, rich in marine biodiversity, are also hotspots for illegal fishing, overexploitation of marine resources, and environmental degradation.

Without a reliable and transparent tracking system, governments and conservationists struggle to enforce regulations, protect fish stocks, and monitor maritime security.

The implications of this dark vessel activity extend far beyond fishing. More than one billion people depend on the ocean as their primary food source, and 260 million people are directly employed by global marine fisheries.

Additionally, 80% of all traded goods are transported via ocean routes, and nearly 30% of the world’s oil production occurs offshore. Without accurate tracking, illegal activities such as forced labor, human trafficking, and environmental crimes can continue unchecked, undermining efforts to promote sustainable ocean management.

AI and satellites reveal dark vessels

To address the limitations of AIS and other conventional tracking systems, the researchers turned to artificial intelligence and satellite technology.

They used deep learning models to scan a staggering two petabytes of satellite imagery from the European Space Agency’s Sentinel-1 satellite constellation. This AI-powered system was trained to detect and classify vessels with remarkable accuracy, far surpassing previous methods.

The team designed and trained three deep convolutional neural networks to analyze satellite imagery and vessel GPS data.

These models achieved an object detection accuracy of over 97%, a classification accuracy of 98% for offshore infrastructure, and a 90% accuracy rate for distinguishing fishing vessels from non-fishing vessels.

Unveiling untracked vessel activity

The dataset used for this analysis was massive. Researchers examined 67 million image tiles, including 53 billion AIS vessel positions, to determine which ships were actively broadcasting their location and which were operating in the shadows.

The resolution of the satellite radar allowed the team to detect objects as small as 15 meters, making it possible to track industrial fishing vessels, cargo ships, tankers, and offshore infrastructure with unprecedented clarity.

“Our satellite mapping revealed high densities of vessel activity in large areas of the ocean that previously showed little to no vessel activity by public tracking systems,” the research team stated.

The study’s findings have already reshaped our understanding of global maritime activity, revealing areas where fishing and transport vessels operate without oversight.

This new method of tracking vessels will be instrumental in identifying illegal fishing hotspots, detecting human rights violations at sea, and improving enforcement of marine protected areas (MPAs).

Rise of offshore energy: Wind vs. oil

Beyond vessel movements, the study also mapped the rapid expansion of offshore energy infrastructure.

By 2021, offshore wind turbines had surpassed oil structures in number, a significant milestone in the transition toward renewable energy. Wind power accounted for 48% of all offshore structures, while oil installations made up 38%.

Despite the growth of wind energy, oil-related vessel traffic still dwarfs that of wind infrastructure, with oil platforms generating five times more vessel activity than wind farms. The global shift to offshore renewables is happening, but oil remains dominant in terms of maritime traffic and industrial footprint.

Growing footprint of offshore energy

The study from Global Fishing Watch found that offshore wind farms are highly concentrated in northern Europe (52%) and China (45%), with China experiencing an extraordinary 900% increase in offshore wind turbines from 2017 to 2021.

Meanwhile, offshore oil infrastructure remains concentrated in the Gulf of Mexico, the Persian Gulf, and Southeast Asia, with the United States, Saudi Arabia, and Indonesia leading in oil platform installations.

As renewable energy infrastructure continues to grow, understanding how these structures interact with existing maritime industries will be crucial. The study found that trawlers avoid fishing within one kilometer of oil platforms, likely to prevent net entanglement.

However, other fishing activities increase around offshore infrastructure, as these structures can serve as artificial reefs that attract marine life.

Future of maritime surveillance

In addition to satellite-based vessel tracking, new AI-driven technologies are set to revolutionize real-time ship detection. The Rapid Earth Monitoring Information System (REMIS), developed in partnership with ESA, S[&]T, Vake, and EmLogic in Norway, promises to locate ships in hours instead of days.

Current satellite monitoring relies on downlinking images, processing them on the ground, and analyzing them manually, which can take days. By the time authorities receive data, dark vessels may have moved on, making enforcement difficult.

REMIS will pre-filter images in space, prioritizing those containing ships before sending them to ground stations. This drastically reduces data transmission time and processing costs, enabling authorities to track vessels in near real-time.

“If we can already identify ships onboard and potentially even combine it with AI systems, we could mark dark vessels and prioritize the scenes containing ships or their locations,” explains Maris Tali, the technical officer leading the project.

This system will be particularly valuable for detecting illegal fishing vessels, preventing ship collisions, and redirecting maritime traffic during emergencies. It represents a significant leap forward in global ocean monitoring.

Impact of COVID-19 on fishing activity

The study also examined how maritime activity was affected by the COVID-19 pandemic. While global fishing activity dropped by 12% in 2020, it has not yet returned to pre-pandemic levels. However, transport and energy-related vessel activity remained relatively unaffected during the same period.

This decline in fishing is part of a longer-term trend. Since the 1980s, global marine fish catch has remained stagnant, as many fisheries have reached or exceeded sustainable limits. Meanwhile, offshore energy and maritime trade continue to expand, reshaping human interactions with the ocean.

As industrialization of the ocean accelerates, conflicts between fisheries, energy developers, and conservationists are likely to increase.

Understanding these trends is essential for policymakers, environmental groups, and industry leaders to make informed decisions about marine resource management.

Call for transparency and accountability

The findings of this study highlight the urgent need for greater transparency in maritime activity. With three-quarters of industrial fishing occurring outside public tracking systems, governments must adopt stricter regulations and better enforcement mechanisms.

AI-powered satellite monitoring and real-time detection systems like REMIS offer powerful new tools to combat illegal fishing, improve ocean governance, and enforce environmental protections.

As human activity in the ocean continues to grow, the need for accountability, sustainability, and international cooperation has never been greater. By illuminating the hidden industrial fleet operating in our oceans, science and technology are paving the way for a more transparent and sustainable future.

The study is published in the journal Nature.

Image Credit: European Space Agency

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