Researchers used wandering albatrosses like these to find fishing boats that may have been avoiding detection.

PAUL SUTHERLAND/Nat Geo image Collection

Seabird ‘cops’ spy on sneaky fishing vessels

Sometimes fishing vessels vanish: Captains turn off beacons that broadcast their locations, leaving regulators wondering whether the boats are fishing illegally. Now, researchers have shown that albatrosses bearing small radar detectors can find these suspicious vessels—even in the middle of the open ocean. After a 6-month study with the large seabirds, the researchers estimate that more than one-third of vessels in the southern Indian Ocean are sailing undercover, confirming concerns about illegal or unreported fishing.

“These are animal cops,” says marine ecologist Boris Worm of Dalhousie University, who calls the work “groundbreaking.” In the future, patrolling seabirds might help reveal fishing grounds that should be targeted for enforcement. “You’re empowering animals to survey their own environment for conservation purposes,” Worm says. “That’s pretty cool.” The strategy could also help albatrosses themselves, which can be killed when they get caught in fishing gear or accidentally eat baited fishing hooks.

Illegal fishing is a major concern for conservation biologists, especially in remote areas. Over the past decade, scientists have studied the problem with data from automatic identification systems (AISs) on ships, which include beacons that constantly send their identity, location, speed, and direction to satellites. To prevent collisions, all vessels about 20 meters or longer must have AIS transponders. Many smaller vessels also have AISs. The data are turned into real-time maps of maritime traffic, giving captains a bigger picture than provided by ship-borne radar alone.

But AISs can be turned off, even though they are required within 320 kilometers of shore—areas referred to as nations’ exclusive economic zones (EEZs). Researchers suspect that fishing vessels turn off AISs when they are fishing illegally or want to prevent competitors from knowing where they are hauling in a good catch. “It’s easy to understand why they turn it off,” says Henri Weimerskirch, an ecologist at the Centre of Biological Studies Chizé.

Albatrosses make good spies. The birds, which prey on fish, can spot a fishing vessel from as far away as 30 kilometers. Some species fly hundreds or thousands of kilometers while foraging.

To get near-instant intelligence from the birds, Weimerskirch and his colleagues spent 3 years developing data loggers that detect radar signals from boats and quickly transmit the location via the Argos system of research satellites. Because boats are unlikely to turn off their marine radar, which they need to prevent collisions, birds wearing the 65-gram loggers were able to pick up signals from previously undetectable ships. In an initial 2017 study with the data loggers, Weimerskirch and colleagues showed that albatrosses from the Crozet Islands (about 2300 kilometers south of Madagascar) flew across 10 million square kilometers of the western Indian Ocean. Almost 80% of them encountered ships.

For the new study, the team scaled up. Weimerskirch and his colleagues taped data loggers to the feathers of 169 albatrosses from Crozet and two other islands to the east. Between December 2018 and June 2019, the birds encountered 353 ships. Those locations were transmitted to the lab typically in less than 2 hours. If they did not match the locations of vessels with an active AIS beacon, the team knew the ships had switched it off. The result: Twenty-six percent of the vessels had illegally turned off their AIS within the EEZ of the three islands, the team reports this week in the Proceedings of the National Academy of Sciences. In international waters, 37% of detected vessels had their AIS switched off.

Those figures square with estimates based on other methods, says David Kroodsma, director of research for Global Fishing Watch, a nonprofit that analyzes AIS data. He says animal-based surveillance would improve AIS analysis by helping show which fishing areas require tighter enforcement. Although the albatrosses can detect vessels, they cannot track them over longer distances, he says. “The trick with dark targets is that you get snapshots,” he says. “What you need to do is look for patterns.”

The data loggers will be deployed in March and April around the Prince Edward Islands in the southern Indian Ocean to reveal the extent of illegal fishing around these sub-Antarctic islands. They will also be used to help New Zealand’s fishery service understand the risk fishing vessels pose to albatrosses. The new study has already shown that older birds encounter boats more than juveniles. Species differ, too: Wandering albatrosses were more attracted to boats than Amsterdam albatrosses.

As his team logs the new data, Weimerskirch is working to develop smaller detectors that could be used on other birds—or even turtles. “There are plenty of applications,” he says.