The Northern Madtom . . . a Species at Risk in Ontario

This species has been identified as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). This species is currently being considered for listing under the federal Species at Risk Act (SARA). If listed, it will be afforded protection under the SARA. This species also has the general protection given by the habitat protection provisions sections of the Fisheries Act.

General Description

Noturus stigmosus

© Joseph R.Tomelleri

The Northern Madtom (Noturus stigmosus) is a member of the Bullhead Catfishes family (Ictaluridae) and has the following characteristics:

• Four pairs of characteristic “barbels” (or whiskers) at the mouth
• Usually 51-76 mm long
• Sharp pectoral spines with poison glands, single spine also located on the dorsal fin
• Tissue connecting the adipose fin with the caudal fin is deeply notched (fins appear separate)
• Premaxillary tooth patch straight without posterior extensions
• Mottled olive-gray colour dorsally with three dark saddle bands, ventral surface dull white
• Two pale spots usually present anterior to the dorsal fin
• Fins pale with darker crescents or markings, and pale edges

Distribution

The Northern 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 known occurrences worldwide. In Canada, the Northern Madtom is found in Lake St. Clair, and the Detroit River, as well as the Thames and Sydenham Rivers. It was first recorded in Canada in 1963. This species is at the northern limit of its range in Canada.

Habitat and Life History

The Ontario population is unusual in that individuals have been caught in deep waters in the Detroit River and Lake St. Clair, whereas typically, the Northern Madtom prefers large creeks and small rivers. It usually avoids extremely silty situations and prefers areas with little cover and a moderate current and rocky substrate. The eggs are laid in the current under flat stones.

Diet

This species is a bottom dweller and feeds on insect larvae, small crustacea and even small fishes. As a nocturnal species, the Northern Madtom relies upon its chemical sensors and barbels rather than its eyesight to detect its prey.

Threats

The greatest threats to the Northern Madtom include declining water quality, channelization, siltation and chemical runoff from agriculture and urbanization.

Similar Species

This species differs from the Brindled Madtom (Noturus miurus) which has four blackish saddle bars and lacks the two pale spots anterior to the dorsal fin found on the Northern Madtom. It also has a premaxillary tooth patch with posterial extensions.

For more information, visit the SARA Registry Website at www.SARAregistry.gc.ca.