The freshwater pearl mussel is one of the most endangered invertebrates in Europe. Its welfare is inseparable from river ecosystem health and salmon habitat restoration.
The welfare of individual freshwater pearl mussels is compromised by poor water quality that causes filtration difficulty and reduced metabolic efficiency. Siltation of river beds blocks oxygen supply to the mussel's burrow environment. Illegal disturbance including pearl poaching causes direct injury and death to some of the oldest animals in Britain. The failure of larval recruitment in many populations due to Atlantic salmon decline means that aging populations cannot replace themselves, creating a welfare crisis that operates at the timescale of centuries. Each mussel that dies from water quality failure or illegal disturbance represents the loss of an individual that may have lived since before the industrial revolution.