A new study published in the journal Nature offers an unprecedented view of previously unmapped industrial use of the ocean and how it is changing.

We’re excited to announce the release of a new study published today in the journal Nature offering an unprecedented view of previously unmapped industrial use of the ocean and how it is changing. The groundbreaking research — led by Global Fishing Watch and co-authored by SkyTruth’s geospatial engineer, Christian Thomas — used machine learning and satellite imagery to create the first global map of large vessel traffic and offshore infrastructure, finding a remarkable amount of activity that was previously “dark” to public monitoring systems.

Key findings:

• About 75% of the world’s industrial fishing vessels are not publicly tracked, with much of that fishing taking place around Africa and South Asia.
• About 25% of transport and energy vessel activity is missing from public tracking systems.
• Fishing activity dropped globally by about 12% from 2017 to 2021, coinciding with the COVID-19 pandemic.
• Offshore energy development surged from 2017 to 2021, including a 16% increase in oil structures and more than doubling of wind turbines.

“It’s super exciting to see this come out after so many years of research,” said Thomas. “It’s a huge benefit to have data like this to protect the ocean and address the climate crisis.”

Researchers from Global Fishing Watch, the University of Wisconsin-Madison, Duke University, UC Santa Barbara, and SkyTruth analyzed 2 petabytes of satellite imagery spanning 2017-2021 to detect vessels and offshore infrastructure in coastal waters across six continents where more than three-quarters of industrial activity is concentrated. The team developed three deep-learning neural networks to identify objects within the dataset (which achieved over 97% accuracy) and classify them as infrastructure, fishing vessels, or non-fishing vessels.

The ocean is an important resource: over 1 billion people rely on it as a primary food source and 80% of the world’s traded goods are shipped across it. However, a large portion of sea-faring vessels remain untracked. This is due to vessels not being required to broadcast their coordinates — some also may intentionally obscure or manipulate them, in the case of illegal activity — or their positions being withheld by local governments. Similarly, details regarding the development of offshore infrastructure are typically kept private by many nations, which has led to a lack of accurate information on human presence in the ocean.

At any given moment, on average, 63,000 vessels were detected during the analysis: 42–49% of these were fishing vessels. Of these fishing vessels, around 72–76% were not publicly trackable. At the same time, the researchers identified 28,000 pieces of offshore infrastructure at the end of 2021, with 48% and 38% corresponding to wind energy and oil production, respectively.

The lack of a comprehensive understanding of where activity occurs in the ocean may affect the growth of industries such as offshore wind generation, mining, shipping, and fishing. At the same time, a more detailed map of human activity in the ocean can help to better inform estimates of greenhouse gas emissions and global fishing trends.

“Identifying offshore infrastructure is critical for understanding offshore energy development impacts and trends, and is crucial data for our work to detect marine pollution events and hold responsible parties to account,” said Thomas. “For example, if we want to understand how much offshore oil and gas infrastructure is leaking methane into the atmosphere, it helps first to know where all of these facilities are located [to better target methane-detecting satellites].”

These findings have already been incorporated into Cerulean, SkyTruth’s new global monitoring system that uses satellite imagery to detect oil slicks and their potential sources, as many spills come from oil and gas infrastructure.

Offshore energy development surged during the study period. Oil structures increased by 16 percent, while wind turbines more than doubled. By 2021, turbines outnumbered oil platforms. China’s offshore wind energy had the most striking growth, increasing ninefold from 2017 to 2021.

“A new industrial revolution has been emerging in our seas undetected—until now,” said David Kroodsma, director of research and innovation at Global Fishing Watch and co-lead author of the study. “On land, we have detailed maps of almost every road and building on the planet. In contrast, growth in our ocean has been largely hidden from public view. This study helps eliminate the blind spots and shed light on the breadth and intensity of human activity at sea.”

While not all boats are legally required to broadcast their position, vessels absent from public monitoring systems, often termed “dark vessels,” pose major challenges for protecting and managing natural resources. Researchers found numerous dark fishing vessels inside many marine protected areas, and a high concentration of vessels in many countries’ waters that previously showed little-to-no vessel activity by public monitoring systems.

The study also shows how human activity in the ocean is changing. Coinciding with the COVID-19 pandemic, fishing activity dropped globally by about 12 percent, with an 8 percent decline in China and a 14 percent drop elsewhere. In contrast, transport and energy vessel activity remained stable.

The study highlights the potential of this new technology to tackle climate change. Mapping all vessel traffic will improve estimates of greenhouse gas emissions at sea, while maps of infrastructure can inform wind development or aid in tracking marine degradation caused by oil exploration.

The open data and technology used in the study can help governments, researchers and civil society to identify hotspots of potentially illegal activity, determine where industrial fishing vessels may be encroaching on artisanal fishing grounds, or simply better understand vessel traffic in their waters.

“Overall the study contributes to a better understanding of the cumulative footprint of human activity at sea, giving us more of an ability to monitor and protect this important environmental resource,” said Thomas.

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