Status of the Wavy-rayed Lampmussel, Lampsilis fasciola (Bivalvia : Unionidae), in Ontario and Canada

The Wavy-rayed Lampmussel, Lampsilis fasciola, is a medium-sized freshwater mussel that inhabits substrates of gravel and sand in clear, hydrologicall y stable streams and small rivers. Its most probable fish hosts are the Sma llmouth Bass (Micropterus dolomieu) and Largemouth Bass (Micropterus salmoi des). It was once widely distributed (although uncommon) throughout the Ohi o and Mississippi drainages and tributaries to the lower Great Lakes, but h as declined significantly in recent years. It is listed as endangered in Il linois, threatened in Michigan and New York, and of special concern or inte rest in Indiana, Ohio and North Carolina. Its range in Canada included west ern Lake Erie, Lake St. Clair, and the Grand, Thames, Sydenham, Detroit, Au sable and Maitland rivers. Its numbers in Great Lakes waters have been redu ced by the Zebra Mussel, Dreissena polymorpha, and populations in the Thame s, Sydenham and Ausable rivers are disappearing or have been lost primarily as a result of agricultural impacts. The healthiest remaining populations in Ontario are found in a 60 km reach of the upper Grand River, but their f uture is uncertain because of fishing pressures on their host fish, increas ing disturbance from recreational activities such as canoeing, and an antic ipated decline in water quality accompanying the rapid rate of human popula tion growth that is projected for the watershed.