Freshwater pearl mussels are critically endangered in the UK and their welfare is inextricably linked to water quality and host fish availability.
Freshwater pearl mussels are sedentary bivalves and their welfare assessment is scientifically uncertain. However as one of the world's most endangered animals each individual's death through pollution or illegal harvest represents a significant conservation harm. The very long lifespan means individuals experience chronic low-level welfare compromise from sub-optimal water quality for decades before death.