Northern gannets are spectacular plunge-diving seabirds that forage up to 500km from their colonies. Their welfare at sea depends on sufficient prey availability, collision avoidance, and avoiding entanglement in fishing gear.
Gannet welfare at sea involves the extreme physical demands of long-distance foraging combined with increasing anthropogenic hazards. The physiological cost of repeated high-speed plunge-dives during foraging trips lasting 1-3 days is substantial, and birds that fail to find adequate prey return to colonies in depleted condition. Climate change affecting the distribution and abundance of sandeel and herring prey forces birds to travel further for equivalent energy intake. Collision with offshore wind turbine structures represents an emerging welfare concern: gannets pursuing diving fish may not detect turbine structures during high-speed dives. Entanglement in discarded monofilament fishing line and other marine debris during plunge-diving causes injury and death. Systematic offshore wind farm environmental impact assessment that includes gannet collision risk modelling helps inform turbine placement decisions.