Visual deterrents lower seabird bycatch in gillnets

Above-water deterrents attached to fishing gear can significantly reduce accidental seabird drownings in gillnets, according to research published in Conservation Letters. Investigators tested two devices in waters off Cornwall, England: floating buoys topped with spinning artificial eyes and kites modeled after predatory birds.

Nets featuring the bird-of-prey kites decreased the likelihood of catching auks—a family of seabirds that includes guillemots and razorbills—by 71 percent compared to untagged nets. Gear using the eye-topped buoys lowered those odds by 59 percent.

Diving seabirds face severe risks from submerged gillnets, with earlier reviews estimating that more than 95,000 seabirds per year die across Baltic and Northeast Atlantic fisheries. To test mitigation gear during real-world fishing operations, scientists enlisted 10 Cornish fishers from October 2023 through March 2025. Boats deployed nets in pairs positioned at least 200 meters apart, tracking each haul with onboard cameras and GPS devices.

In total, participating crews deployed 1,057 nets spanning roughly 129 kilometers (80 miles). The gear caught 191 non-target animals, including 153 birds alongside 25 seals and 13 cetaceans like porpoises and dolphins. Guillemots and razorbills accounted for nearly three-quarters of the total, with almost all found dead upon retrieval.

Operational Challenges and Targeted Solutions

The trial highlighted notable differences in device performance. Kites proved most effective within a 30-meter radius, though fishers noted they failed in light breezes and were difficult to manage during strong winds. Buoys were easier to operate and store, but catch data suggested they might attract seals, with 15 captured in buoy nets compared to four in kite nets and six in control nets.

Researchers also cautioned that birds could habituate to visual threats over time, referencing a separate study in Denmark where buoys lost their scaring effect on cormorants and gulls after roughly a month. In the English trial, bycatch peaked during January and February, particularly when using 100-to-110-millimeter mesh to catch sea bass and mackerel. The study authors suggest that brief, targeted winter deployments rather than permanent mandates could offer a practical, effective way to protect vulnerable seabirds.