Off the coast of Korsør, Denmark, two unblinking mechanical eyes spin in the wind above a fishing net, their oversized pupils painted to mimic the stare of a hunting predator. These are Looming-Eye Buoys, and for a few weeks last year, they worked remarkably well—until the seabirds figured out they were fake.
Fish-eating seabirds like great cormorants and large gulls have long posed a dilemma for Danish fisheries. The birds swoop down to feed on fish trapped in nets, damaging catches and eating into profits. Worse, the encounters sometimes result in accidental deaths of the birds themselves. Since these species are legally protected, killing them is not an option. Fishers have tried scarecrows and other decoys before, but seabirds are quick learners—they soon realize a stationary fake isn't a real threat and return to their feeding grounds undeterred.
Researchers from the Technical University of Denmark partnered with Fishtek Marine, a UK company, to test a more dynamic approach. The Looming-Eye Buoy is a small floating device with wind-powered spinning blades covered in eye-shaped patterns designed to suggest a watching predator. The idea is that the moving, blinking effect might fool birds longer than a static fake could.
The team deployed two LEBs at a pound net—a large, stationary fish trap anchored by wooden poles—off Korsør and kept a nearby trap as an untreated control site. Trained observers stood on shore for 46 days, carefully counting cormorants and gulls at both locations before and after the devices were installed. The first few weeks delivered promising results. The number of birds clustering around the test trap dropped noticeably and measurably. It seemed the spinning eyes might have finally cracked the code.
But seabirds, it turns out, are patient teachers of themselves. By day 46, the birds had caught on. The difference between the site with LEBs and the undefended trap vanished. The deterrent effect, the team reported in the journal Royal Society Open Science, faded rapidly and disappeared completely after about a month.
The findings aren't a failure—they're a useful clarification. The researchers suggest that Looming-Eye Buoys work best as a short-term solution, ideal for seasonal fisheries that last less than a month. Used intermittently, or combined with other deterrent methods, they might offer better results than a one-device-fits-all approach. The study shows that even clever innovations have limits when pitted against animals as adaptable as seabirds.
What this reveals is the deeper challenge of sustainable fishing: finding humane ways to protect both livelihoods and protected wildlife requires not a silver bullet, but a toolkit. The Looming-Eye Buoy is one tool that works—just not forever.