Eurasian and North American otters have recovered in many regions following pollution reduction, but continue to face threats from pesticides, road mortality, and habitat fragmentation.
Otter welfare reflects the health of entire freshwater catchments. As apex predators in river systems, otters bioaccumulate pollutants from every level of the food chain, making their health status a sensitive indicator of aquatic contamination. The collapse and recovery of European otter populations is one of conservation biology's success stories, demonstrating that even severely depleted populations can recover when root causes are addressed. Current welfare challenges center on road mortality — otters follow linear river systems that frequently intersect with roads, and culverts too small to pass through force otters onto road surfaces. Otter road crossing structures — large culverts with ledges above water level — dramatically reduce mortality at crossing hotspots and have been successfully implemented across Europe.