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

Abstract

The Wavy-rayed Lampmussel, Lampsilis fasciola, is a medium-sized freshwater mussel that inhabits substrates of gravel and sand in clear, hydrologically stable streams and small rivers. Its most probable fish hosts are the Smallmouth Bass (Micropterus dolomieu) and Largemouth Bass (Micropterus salmoides). It was once widely distributed (although uncommon) throughout the Ohio and Mississippi drainages and tributaries to the lower Great Lakes, but has declined significantly in recent years. It is listed as endangered in Illinois, threatened in Michigan and New York, and of special concern or interest in Indiana, Ohio and North Carolina. Its range in Canada included western Lake Erie, Lake St. Clair, and the Grand, Thames, Sydenham, Detroit, Ausable and Maitland rivers. Its numbers in Great Lakes waters have been reduced by the Zebra Mussel, Dreissena polymorpha, and populations in the Thames, 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 future is uncertain because of fishing pressures on their host fish, increasing disturbance from recreational activities such as canoeing, and an anticipated decline in water quality accompanying the rapid rate of human population growth that is projected for the watershed.