M. margaritifera lives in swift, generally acid, rivers in sand or gravel at a depth of ½–1½ m. Post-glochidial mussels burrow in the sediment and the smallest may also be secured by byssus. M. margaritifera has been subject to commercial pearl fishing at least since Roman times, but very few full-time professional pearl fishers remain in Britain. They take only mussels over 80 mm long and seldom over-exploit mussel beds. However, some beds have been stripped of juveniles as well and this practice may have contributed to the apparent decline of the species in Britain. Some form of protection may become necessary if the practice continues.