FURTHER RANGE EXTENSIONS OF THE CRAYFISH ORCONECTES-RUSTICUS IN THE LAKE-SUPERIOR BASIN OF NORTHWESTERN ONTARIO

The introducted exotic crayfish, Orconectes rusticus has now extended its range to six additional localities in northwestern Ontario, including a first record from Lake Superior. This species could have considerable impact on the littoral zone of low nutrient lakes in the region. Among the possible adverse effects are (1) the reduction or elimination of macrophyte beds, (2) the elimination or reduction of native crayfish species, (3) reduction in the density and species richness of the benthic insect community, (4) direct competition with fish for macrobenthos, (5) elimination of nursery areas for fish and (6) possible predation on the eggs and larvae of substrate spawning fish.