High-contrast Banners Designed to Deter Seabirds from Gillnets Reduce Target Fish Catch

The incidental catch of non-target species in fishing gear (i.e., bycatch) is a global threat to sustainability and conservation in marine systems. Seabirds experience substantial bycatch mortality, with gillnets having the greatest impacts of any fishing gear. Widespread mitigation to reduce seabird bycatch in gillnet fisheries is tenuous, and information on bycatch in inshore surface-set gillnets remains a major knowledge gap. To help address these issues, we collaborated with commercial fishers to test the efficacy of high-contrast banners designed to alert seabirds. In waters of Newfoundland, Canada, banners were attached to surface-set gillnets for Atlantic Herring Clupea harengus and were compared with simultaneously unmodified control nets within the foraging ranges of major seabird colonies. The banners reduced target catch, creating a non viable option for fishers. Seabird bycatch was low, although it may have been more substantial than indicated by local information sources. Bycatch included fish species of concern (Atlantic Salmon Salmo salar and Porbeagle Shark Lamna nasus). Owing to the episodic nature of seabird and other non-target catch, collaboration with fishers is needed to continue long-term monitoring of inshore gillnet bycatch.