History of the range extension of Orconectes rusticus into northwestern Ontario and Lake Superior

First discovered in one lake in 1985, Orconectes rusticus, an introduced exotic, has now extended its distributional range in Northwestern Ontario to 10 localities extending from the international border (Pigeon River) to the Sibley Peninsula. It has reached nuisance densities in three locations, eliminating the native species; has established reproducing populations in 5; and is currently expanding into 5 new localities. Its downstream rate of expansion varies from 0.9 to 3.7 km/yr upstream at 0.5 km/yr. Serial impoundment of streams by beavers temporarily slows the rate of expansion. Waterfalls and dams prevent upstream movement. If present rate of expansion continues, Orconectes rusticus will become the dominant species in Western Lake Superior tributaries and portions of the lake.