The Eurasian otter was driven to near-extinction in Britain by organochlorine pesticides in the 1960s and 1970s, and has made a remarkable recovery following pesticide bans, demonstrating the power of pollution control for mammal welfare.
Otter welfare today is primarily threatened by road mortality at road-river crossings, which kills hundreds of otters annually across Britain. Mange and other diseases affect some populations. Recreational disturbance at known holt sites can cause abandonment during the breeding season. Secondary poisoning from rodenticides accumulated in fish prey is an emerging welfare concern. Fish stocks damaged by pollution or over-abstraction reduce the food availability on which otter health depends.