The Eurasian otter recovered dramatically in UK rivers after organochlorine pesticide bans in the 1980s. Despite this success, otters face ongoing threats from road mortality, water pollution and fish availability decline.
Otters at culverts face mortality through two mechanisms: failing to find the culvert entrance during floods and entering road culverts where they are struck by traffic. Otter ledges installed beside road culverts — simple platforms allowing otters to walk around the road — have dramatically reduced road kill at monitored sites. Water pollution affecting fish stocks forces otters to travel further to find food, increasing road crossing frequency and energy expenditure. Maintaining clean rivers with abundant fish directly improves otter welfare and reduces stress behaviour.