Eurasian otters have recovered significantly following persecution and pollution bans. Their welfare as river ecosystem indicators depends on clean water, adequate prey, and protection from road mortality.
Otter welfare is closely tied to water quality and fish population health. Pollution from agricultural runoff, sewage, and industrial discharge reduces prey availability and can cause direct toxicity through bioaccumulation. Road mortality at river crossings causes traumatic deaths of wild otters, with cubs losing parents and dying from starvation. Otter holt destruction through riverbank development eliminates breeding sites essential for reproductive success. Wildlife crossings at road-river intersections significantly reduce mortality. The positive welfare story of otter recovery — from near-extinction to widespread presence in many European countries — demonstrates that pollution reduction and protection from persecution can allow population recovery within decades.