Features: The Northern Madtom (Noturus stigmosus) is a small, stout catfish with characteristic "barbels" (or whiskers) at the mouth, and sharp spines with poison glands that can inflict a painful wound. The species is cryptically coloured a mottled brown, and the tissue connecting the adipose fin with the caudal fin is deeply notched (so much so that it appears as if the adipose and caudal fins are separate). The Ontario population is unusual in that individuals have been caught deep out into Lake St. Clair, whereas generally the Northern Madtom prefers fast-flowing creeks and rivers with a rocky substrate. A bottom-dweller, this species is nocturnal and feeds on insect larvae, small crustacea, and even small fish. The eyes are reduced, so prey detection is mainly by chemical cues and then by touch with the mouth barbels.

Status: Endangered Provincially and Nationally

Range: The Northen Madtom lives in eastern North America, ranging from Ontario south to Mississippi and Tennesee, west to Michigan. It is a globally rare species, with less than 100 occurrences. In Ontario, Northern Madtom is currently known to be in the Upper Detroit River, Lake St. Clair, and the lower Thames River. Surveys in Lake St. Clair suggest the species is expanding in this area. There is one record of Northern Madtom from the Sydenham River, but repeated surveys there recently have failed to find the species. The Sydenham specimen was caught in 1975 and initially identified as a Brindled Madtom. However, it was recently re-examined by ROM expert Erling Holm, who determined that it was a Northern Madtom. Range Maps

Threats: The Northern Madtom was first recorded in Canada in 1963, so there is no good information on historical declines here. Initially considered to be a recent introduction from the United States, biologists now think that Northern Madtom may have been here much longer, and because of its similarity to two other Madtom species here (especially Brindled Madtom), was being overlooked. This species is at the northern limit of its range in Canada and is probably limited by water temperature. Populations may be threatened by pollution in Lake St. Clair and the Detroit River. However, these populations have persisted in this corridor in the face of considerable contaminants in the past. Inland populations (Thames River and Sydenham River) may be threatened by water quality changes and siltation associated with agricultural land use and urban development.

The recent invasion of Lake St. Clair by an exotic fish species, the Round Goby (Neogobius melanostomus), may have a negative impact on Northern Madtom.

Protection: Under Ontario's Endangered Species Act, 2007, the Northern Madtom is protected from any actions that may cause harm to the species. The species has the general protection given by habitat sections of the Fisheries Act.

Text Sources: Holm and Mandrak 2001

Last Modified Date: October 2008