At low tide, extensive mud flats are exposed, and these are an important feeding source for wading birds. Along with other rias in South West England, the Exe estuary is an important site for wintering waders. Dawlish Warren is a favoured site for birdwatching. The river has a low pH but does not suffer from a serious acid rain problem. It is populated with wild brown trout , and in the lower reaches coarse fish including dace, chub, perch, roach, pike and bream and some grayling, the average size being . There is a run of Atlantic salmon and a sparse run of sea trout. Just below the union of the River Barle is Black Pool, which is one of the best, and highest salmon pools on the river. The smaller fish species present include stone loach and there are good reasons to assume others are present.