Freshwater pearl mussels are one of the most endangered animals in Britain, whose welfare depends on pristine water quality and restoration of their salmonid host fish populations.
Freshwater pearl mussels occupy a complex welfare position as long-lived animals with basic nervous systems. Their populations have declined catastrophically from water pollution, riparian habitat loss, and illegal pearling. The welfare of individual mussels is difficult to assess, but population-level welfare in terms of survival and reproduction is severely compromised. Their larval dependence on healthy juvenile salmonid populations means that restoration is inseparable from river ecosystem health, benefiting the welfare of multiple species simultaneously.