Study finds abandoned tuna fishing rafts reached more than half of the world's protected marine areas

While humans can designate certain ocean areas as protected zones where fishing is prohibited, keeping human debris and pollution from flowing into those regions presents a different kind of challenge altogether. 

For example, tuna fishing gear deployed in areas where fishing is legal often ends up in protected spaces. 

What happened?

According to a new worldwide analysis cited by Mongabay, drifting fish aggregating devices, or dFADs, are reaching waters that make up more than half of the world's protected marine area.

In research published in Science Advances, scientists identified at least 6,324 documented dFAD strandings from 2007 through 2023 in 174 protected areas across 53 maritime jurisdictions, Mongabay reported.

Boris Worm, a co-author of the study and a marine ecologist at Dalhousie University in Canada, said the extent of the issue was striking.

"We were surprised to find that FADs appear to affect more than half of the world's protected marine area, and that impacts often occurred thousands of kilometers from the original fishing grounds," Worm told Mongabay.

The team also investigated whether fleets were focusing dFAD activity just outside major marine protected areas. Although overall fishing with the devices has risen near those zones, the researchers did not find clear broad-scale evidence of intentional clustering there.

Why does it matter?

Marine protected areas are intended to help ocean ecosystems recover, safeguard threatened wildlife, and support coastal communities. But the study suggests that designating boundaries alone is not enough to keep industrial debris from drifting inside.

Once they wash up, dFADs can smother or damage coral reefs and trap sharks, turtles, and other marine life. And even when parts of the rafts are designed to biodegrade more easily, plastic pieces and electronic components may still be left behind.

Mongabay reported that roughly 30% of protected areas with recorded or inferred strandings were located in small island developing states, where local authorities are often left to pay for retrieval and disposal with limited resources. That can drive up cleanup costs while putting more pressure on ecosystems that support food supplies, employment, and tourism.

Juan Carlos Villaseñor-Derbez, a study co-author and marine scientist at the University of Miami, said restricted access to tracking records remains a major challenge.

"This would allow us to better understand the spatial and temporal dynamics of dFAD fishing in relation to MPA boundaries, while still preserving the privacy aspects of real-time data," he said of releasing historical records.

What's being done?

Researchers and fisheries experts say tighter oversight is needed, particularly after fishing companies stop using dFADs. Mongabay reported that access to historical tracking data could help show where a device was launched, when it was no longer under company control, and whether it entered a protected area by accident or only after its buoy had been turned off.

The authors of the study also said deployment rules should be stricter. As reported by Mongabay, Worm called for annual limits on dFAD deployments and for restrictions in waters upstream of marine protected areas, where currents can carry the devices into those zones.

Glen Holmes, a marine ecologist and international fisheries expert with the Pew Charitable Trusts who was not involved in the study, said regulators should prioritize stopping dFAD abandonment before it happens. He added that politically, design tweaks have been easier to advance than wider reforms meant to reduce device losses.

Holmes added: "Most deployed dFADs are 'lost' either accidentally or intentionally, and so regulating to minimize this 'loss' and therefore minimize the risk of overall interaction with MPAs is, I think, the most important element."

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