River otters serve as sentinel species for freshwater ecosystem health, and their welfare reflects the condition of the aquatic environments they depend on.
River otter welfare is intimately linked to freshwater ecosystem health, making them valuable indicators of environmental conditions affecting the welfare of entire aquatic communities. Pollution that compromises otter health through bioaccumulation or prey reduction also affects the welfare of the fish, amphibians, and invertebrates that form the ecosystem. The documented play behavior of river otters provides behavioral evidence of positive welfare states when environmental conditions are good, offering a visible indicator of ecosystem welfare that resonates with the public. Conservation actions that protect river otter habitat — clean water legislation, wetland protection, and riparian buffer zones — generate welfare benefits across the entire freshwater community.