River otters serve as sentinel species for freshwater ecosystem health, and monitoring their welfare provides early warning of water quality and habitat degradation affecting many species.
River otter welfare is a lens on freshwater ecosystem welfare broadly — these charismatic, wide-ranging predators experience the cumulative health effects of watershed-level water quality, prey abundance, and habitat integrity. Contaminant bioaccumulation from fish prey means that river otter welfare indicators are also indicators of what fish in those rivers are experiencing, and what human communities drawing from those watersheds may be exposed to. Conservation programs protecting river otters thus serve a cascade of welfare interests — the otters themselves, the fish populations they depend on, and the broader freshwater ecosystems they inhabit and indicate.