 Clean, fast-flowing streams and rivers are required for the freshwater pearl mussel, where it lives buried or partly buried in fine gravel and coarse sand, generally in water at depths between 0.5 and 2 metres, but sometimes at greater depths.Clean gravel and sand is essential, particularly for juvenile freshwater pearl mussels, for if the stream or river bottom becomes clogged with silt, they cannot obtain oxygen and will die.Also essential is the presence of a healthy population of salmonids, a group of fish including salmon and trout, on which the freshwater pearl mussel relies for part of its life cycle.