Satellite and AI study finds most marine reserves free of industrial fishing, despite enforcement fears

 By Ron Rocky Coloma

“There is a catch-22 in ocean conservation,” said Dr. Jennifer Raynor. “The better fish recover inside protected areas, the more attractive they become to poachers.”

That paradox drove Raynor and her colleagues to ask a hard question: Are marine protected areas truly working, or are they just lines on a map?

Using satellite imagery and artificial intelligence, Raynor’s team tracked industrial vessels across more than 1,300 fully and highly protected ocean areas.

The result: In nearly 80 percent of them, there was no sign of commercial fishing. Of the rest, the vast majority saw less than 24 hours of suspicious activity in an entire year.

“We show that in places that actually ban industrial fishing, poaching is surprisingly rare,” said Raynor, an assistant professor of natural resource economics at the University of Wisconsin-Madison. “That’s a big win for conservation.”

The research used Synthetic Aperture Radar to detect ships regardless of weather or time of day, even if their location signals were turned off. This was paired with data from Automatic Identification Systems, the GPS pings many industrial vessels are required to broadcast. Combined, the tools offered the clearest global view yet of illegal fishing in protected areas.

Fishing vessel detections were nine times lower in protected waters than in nearby unprotected zones.

“About 96 percent of protected areas had less than one day per year of alleged illegal fishing effort, and 80 percent had none,” Raynor said. “Most of these protected areas showed little to no signs of industrial fishing activity.”

Illegal fishing remains one of the biggest threats to marine ecosystems. It undermines fish population recovery, reduces legal catches and weakens the purpose of reserves. But technology is now making it harder for illegal activity to go unnoticed.

“Enforcement agencies no longer have to rely solely on patrols,” Raynor said. “They can now monitor vast areas remotely and target their efforts where they are needed most, making enforcement easier and more effective.”

Despite the promising findings, Raynor cautioned against complacency. Many countries are rapidly expanding their protected waters to meet the 30x30 global goal — to conserve 30% of oceans and land by 2030 — and oversight may not always keep pace.

“Countries are racing to protect 30% of the ocean by 2030, and there is a widespread view that enforcement may not be keeping up with rapid expansion,” she said. “If these protections don’t hold up, there’s a real risk that we could fall short of global conservation goals and undermine future protection efforts. Our findings push back on that narrative.”

Some of the most visible marine sanctuaries are in the Pacific, including the Phoenix Islands Protected Area in Kiribati and Palau’s National Marine Sanctuary. These countries have received international recognition for their leadership, but they’ve also made economic sacrifices.

“These countries have made some of the biggest sacrifices to invest in the future of the ocean,” Raynor said. “For example, lost fishing revenue is a major motivation for calls to reopen the Phoenix Islands Protected Area. So, there is even more pressure here to ensure that enforcement is effective.”

While some sites like the Galapagos and Cocos Island are already using satellite surveillance for enforcement, Raynor noted a key challenge: Most satellites do not continuously monitor the most remote parts of the ocean.

That’s a problem for large marine sanctuaries, which often stretch across hundreds of thousands of square kilometers and rely heavily on outside support to remain protected.

Raynor’s study focused on industrial vessels over 15 meters long, but many marine protected areas still allow smaller boats that operate outside satellite range. These artisanal or small-scale fishers can still damage ecosystems, even if their impact is harder to track.

“We show that these protected areas are mostly free from industrial fishing, which is an important first step,” Raynor said. “However, some of these areas still allow small-scale or artisanal fishing, which can also cause ecological damage. So, we cannot say whether these ecosystems are healthy or totally free of all fishing.”

The next goal is to apply the same detection techniques to smaller vessels. Global Fishing Watch, which helped develop the AI models used in the study, is already piloting new methods to do that.

“By using satellites to track fishing vessels, countries can predict the locations of illegal activities and target patrol efforts, saving both manpower and money,” Raynor said.

One of the most striking findings was how consistent the results were across regions. Most of the world’s strongest protections appeared to be working.

“Remarkably, there were not just a few cases with high compliance,” Raynor said. “There was little to no industrial fishing in most of the world’s fully and highly protected MPAs.”

Enric Sala, a co-author of the study and founder of National Geographic’s Pristine Seas initiative, said the effect of strong protections goes beyond the reserve boundaries.

“Because strictly protected marine areas discourage illegal fishing, fishes are far more abundant within their boundaries, they produce many more babies and help replenish surrounding areas,” Sala said. “In other words, the fishing industry benefits from following the rules.”

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