Looming-Eye Buoys temporarily reduce the number of fish-eating seabirds in pound nets

Abstract Seabird depredation in fishing gear and aquaculture facilities is documented worldwide and can represent important revenue losses. Although sometimes considered a nuisance, seabirds are also generally protected, so the development of non-lethal methods to reduce depredation is essential to maintain sustainable fishing and aquaculture activities without affecting seabird populations. In the Western Baltic, large fixed traps (pound nets) are used to target migrating fish. This gear attract piscivorous seabirds that feed on the trapped fish. Here, we tested the Looming-Eye Buoy (LEB), a floating windmill with a pair of eyes printed on the wings, intended to produce an aversive effect by mimicking the approach of a predator. Our field study shows that the LEB reduces the number of great cormorants (Phalacrocorax carbo) and large gulls for a short period after initial implementation. After less than a month, the scaring effect of the LEB is not measurable any more, implying that the birds habituate to the device. This questions the long-term deterring effect of the LEB for the seabird species commonly observed in the study area, despite previously encouraging results reported elsewhere. By extension, this suggests that the LEB may not be suitable to reduce seabird by-catch in passive gear regionally.