Freshwater pearl mussels are one of the most endangered animals in Britain and Europe, with populations collapsed due to water quality degradation, poaching, and habitat loss over recent centuries.
Freshwater pearl mussel welfare as invertebrates is debated, but the collapse of populations that represent centuries of individual growth — mature mussels being over 100 years old — is a welfare concern of a different character: the destruction of long-lived individuals through illegal harvest or habitat degradation eliminates irreplaceable individuals from populations that cannot rapidly replenish. The welfare of the salmon and trout that serve as mussel hosts is also relevant — habitat degradation that impairs fish welfare simultaneously eliminates the hosts mussels depend on for juvenile development. River restoration to reduce fine sediment and nutrient pollution, combined with legal protection enforcement, addresses both the direct welfare of mussels and the host fish welfare they depend on.