A wandering albatross coasting over the sea Image courtesy of Alexandre Corbeau

Birds carrying radar sensors have been used to spy on fishing boats, revealing that a quarter of vessels in the Indian Ocean are operating illegally.

Globally, illegal fishing is estimated to cost £17.6 billion a year, but satellite monitoring can be costly, sometimes slow and can miss boats. An international team decided to give flight to a pioneering alternative: strapping sensors to 169 albatrosses and releasing them in the south of the Indian Ocean.

The birds can travel vast distances and are attracted to fishing vessels. The researchers attached sensors that could pick up a boat’s use of radar from about 30 kilometres away, which can then be used to confirm whether the boat’s Automatic Identification System – used for avoiding collisions and allowing authorities to track it – is on.


Between December 2018 and June 2019, they detected a total of 353 fishing boats in the region. Of those operating in countries’ exclusive economic zones (EEZs), where vessels have to declare fishing, 25.8 per cent had their Automatic Identification Systems switched off. Such behaviour is often a sign of illegal fishing.

In international waters, fishing isn’t illegal but should be declared. There, the birds revealed that 36.9 per cent of vessels had the system turned off.

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Henri Weimerskirch at the French National Centre for Scientific Research (CNRS) led the work, and says the success of the project shows it is a cheap form of surveillance that could complement satellite monitoring. “We have shown that it is possible,” he says.

The birds could even be used as part of enforcement efforts in conjunction with navies, because they relay data in real-time, he says.

But to direct them to spy on certain areas would require expert knowledge from ornithologists. And improvements in satellites may do away with the need for bird spies.

“Fortunately for us, and the albatrosses, we soon won’t have to rely on wild animals to do our data collection work for us,” says John Amos at SkyTruth in West Virginia, which uses satellites for environmental protection. “Orbital technologies are rapidly improving and steadily closing the net on shady operators in the ocean.”

He is working with the Global Fishing Watch project to use satellite radar images to detect vessels that don’t broadcast their signal. Other satellite surveillance firms, including Hawkeye 360 and UnseenLabs, are also working to detect shipboard radar.

Journal reference: PNAS, DOI: 10.1073/pnas.1915499117