Led by Global Fishing Watch, the study published in Nature is said to offer an unprecedented view of previously unmapped industrial use of the ocean and how it is changing.
The analysis revealed that around 75 per cent of the world’s industrial fishing vessels are not publicly tracked, mostly around Africa and south Asia. Similarly, over 25 per cent of transport and energy vessel activity is missing from public tracking systems.
Researchers from Global Fishing Watch, the University of Wisconsin-Madison, Duke University, UC Santa Barbara and SkyTruth analysed two million gigabytes of satellite imagery from 2017 – 2021 to detect vessels and offshore infrastructure in coastal waters across six continents.
By synthesising GPS data with five years of radar and optical imagery, the researchers were able to identify ‘dark’ vessels. Using machine learning, they then concluded which of those vessels were likely engaged in fishing activity, to create the ‘most comprehensive’ public picture of global industrial fishing available.
Researchers found that, for instance, public data suggested that Asia and Europe had similar amounts of fishing within their borders, but their mapping revealed that Asia dominates: for every 10 fishing vessels detected on the water, seven were in Asia while only one was in Europe.
In a statement, David Kroodsma, director of research and innovation at Global Fishing Watch and co-lead author of the study, said: “A new industrial revolution has been emerging in our seas undetected - until now.
“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, researchers said that ‘dark fleets’ found inside marine protected areas pose challenges for protecting and managing natural resources.
The study also showed how human activity in the ocean is changing; coinciding with the COVID-19 pandemic, fishing activity dropped globally by about 12 per cent, whilst transport and energy vessel activity remained stable.
Offshore energy development surged during the study period; oil structures increased by 16 per cent, while wind turbines more than doubled. By 2021, turbines outnumbered oil platforms.
Researchers said that mapping all vessel traffic will improve estimates of greenhouse gas emissions at sea to help tackle climate change, while maps of infrastructure can inform wind development or aid in tracking marine degradation caused by oil exploration.
“Previously, this type of satellite monitoring was only available to those who could pay for it. Now it is freely available to all nations,” said Kroodsma. “This study marks the beginning of a new era in ocean management and transparency.”
The study can be read in full here.