Threespine, Gasterosteus aculeatus, and Fourspine, Apeltis quadracus, sticklebacks in the Lake Superior Basin

Abstract

The Threespine (Gasterosteus aculeatus) and Fourspine (Apeltes quadracus) sticklebacks are unintentionally introduced species to Lake Superior with initial populations established near Thunder Bay, Ontario. An examination of annual seining and trawling records show that native sticklebacks have declined in abundance in their native habitats as a result of these introductions. Assuming a single colonization event for Lake Superior, the distribution of Gasterosteus has been extended to the Black River, Ontario, in the east as well as both the Minnesota and Michigan coasts of Lake Superior. Apeltes quadracus is not known from Great Lakes populations outside of Lake Superior. However, specimens have been collected in Lake Superior waters distant from Thunder Bay. Gasterosteus has spread rapidly while Apeltes has not spread as quickly. Apeltes, due to its preference for nearshore areas, has the greatest potential to affect the native fish community negatively. This may occur through competition for habitat and food resources which can ultimately change the food web structure.