Googly-eyed buoys and kites help keep seabirds out of fishing nets, study finds.
Researchers working with 10 Cornish fishers report that bird-of-prey kites and spinning looming-eye buoys, mounted above the water, cut the odds of auks being caught in gillnets by 71% and 59%.
A study off Cornwall, England, found that two above-water deterrents reduced the chance that diving seabirds were caught in gillnets, according to a paper in Conservation Letters. Nets fitted with kites shaped like a bird of prey had 71% lower odds of catching an auk, the bird family that includes guillemots and razorbills. Nets fitted with spinning buoys topped with large eyes had 59% lower odds.
The researchers paid 10 Cornish fishers to take part between October 2023 and March 2025. Cameras and GPS units recorded each haul. Nets were set in pairs, one with a deterrent and one without, at least 200 meters (660 feet) apart. In all, the fishers set 1,057 nets with a combined length of about 129 kilometers (80 miles). The nets caught 191 non-fish animals: 153 birds, 25 seals and 13 cetaceans. Guillemots and razorbills made up nearly three-quarters of the total, and almost all of the animals were dead when hauled aboard.
Gillnets are a major threat to diving birds, which forage underwater and can become tangled in the mesh. A 2024 review found that gillnets in the Baltic Sea and Northeast Atlantic kill more than 95,000 seabirds a year. An earlier trial of the eye buoys in Iceland's lumpfish fishery found no reduction in bycatch. In the Cornwall trial, kites worked better within 30 meters (100 feet), while the buoys were moderately effective over a wider range. The authors suggest improved kites spaced every 60 to 80 meters could suit coastal gillnet fisheries.
Both devices had drawbacks. Fishers said the kites performed poorly in very light winds and were harder to handle in strong winds, while the buoys were easier to handle and store. Fifteen seals were caught in nets with buoys, compared with six in nets without devices and four in kite nets, which hints that buoys may attract seals. The authors say more testing is needed. A separate 2026 Danish study found that the buoys' deterrent effect on cormorants and gulls near a fish trap was gone after about a month. The Cornwall team did not test for this.
Bycatch peaked in January and February, and was highest in sea bass and mackerel nets with mesh of 100 to 110 millimeters. The authors say this points to short, targeted winter deployments rather than year-round rules. Three authors work for Fishtek Marine, which makes the buoys, according to the paper's conflict-of-interest statement. The U.K. government's environment department funded most of the work, and Equinor funded the rest.
Lead author Tom Horton, of the University of Exeter, said: "The biggest surprise was how clear and consistent the results were."
At a Glance
- Kite-fitted nets had 71% lower odds of catching auks, and looming-eye buoy nets had 59% lower odds, off Cornwall.
- Ten fishers set 1,057 nets, about 129 kilometers in total, between October 2023 and March 2025.
- The nets caught 191 non-fish animals, including 153 birds, 25 seals and 13 cetaceans.
- Bycatch peaked in January and February, mainly in sea bass and mackerel nets.
- A Danish study found the buoys stopped deterring birds after about a month.
Sources
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