Information in support of an updated recovery potential assessment of Northern Madtom (Noturus stigmosus) in Canada, 2012–2021

Abstract

The Northern Madtom (Noturus stigmosus) is a small, ictalurid catfish species requiring medium to large streams or rivers with gravel, sand, or cobble substrates and moderate to swift current. In Canada, it is found in the Detroit, St. Clair, and Thames rivers, and Lake St. Clair. It is likely extirpated from the Sydenham River. In April 1993, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) placed Northern Madtom in the Data Deficient category. The species was re-examined in April 1998 and designated as Special Concern. Northern Madtom was re-assessed as Endangered in November 2002 (and again in May 2012) due to its restricted range, a deterioration in water quality, and interactions with invasive species. Subsequent to the 2002 COSEWIC designation, Northern Madtom was listed on Schedule 1 of the Species at Risk Act (SARA) in June 2003. The Recovery Potential Assessment (RPA) provides background information and scientific advice needed to fulfill various requirements of SARA including informing the development of recovery documents and for assessing SARA Section 73 permits. This research document describes the current state of knowledge of the biology, ecology, distribution, population trends, habitat requirements, and threats of Northern Madtom, with updated information from 2012 through 2021. A threat assessment identified the greatest threats to Northern Madtom in Canada as aquatic invasive species, various sources of pollution, climate change, and habitat modifications from shipping channel construction and maintenance. Mitigation measures and alternative activities related to the identified threats that can be used to protect the species are also presented. Knowledge gaps remain surrounding population status through time, the status of the species in the Sydenham River and Lake St. Clair, total habitat extent, and the mechanisms and impacts of major threats.