Margined madtom (Noturus insignis) COSEWIC assessment and status report 2012: chapter 2

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COSEWIC Executive Summary

Description

The margined madtom, Noturus insignis (Richardson 1836), is a small ictalurid (family Ictaluridae). The official French name is chat-fou liséré, although chat-fou livré is used in older literature. This fish has a light cream-coloured belly, a light brown to grey back and chin barbels. Its dorsal and caudal fins are light brown with black edges. Its adipose fin is attached along the length of the body and is continuous with the square caudal fin. Adults are commonly 100 mm in total length. Specimens of margined madtom are rarely captured and may be easily misidentified. 

Distribution

The native U.S. range of the margined madtom includes the Finger Lakes region south towards the Appalachian Highlands and includes most of the Atlantic coastal streams from New York to Georgia. Individuals have also been found in New Hampshire and Michigan (Lee et al. 1980). In Pennsylvania, margined madtom is the most commonly captured madtom species throughout the Susquehanna, Potomac, and Delaware River drainages (Gutowski and Raesly 1993).

Canadian populations are limited to Ontario and Quebec. In Quebec, this fish is found in Gatineau Park, Gatineau County, the Gatineau River, Hull County, the Ottawa River, Hull and Papineau counties and Rivière Lapêche, Gatineau County. There is also an unconfirmed record of capture in the Cole Lake area of Buckingham County. In Ontario, specimens of margined madtom have been found in the Fall River, Mississippi River and Bolton Creek located in Lanark County. Also, specimens have been captured in Lake Joseph, Lake Rosseau, and Lake Muskoka in the Muskokas.

The disjunct distribution of the margined madtom has led to skepticism as to whether the margined madtom is a native or an introduced species. Goodchild (1990) discussed both hypotheses in the original status report and the consensus of the author and the Committee at the 1989 assessment meeting was that it was a native species. Noturus insignus may have immigrated through interconnecting post-glacial lakes 8 000 – 10 000 years ago. Margined madtom is known from several lakes, rivers and streams in separate locations in Muskoka, Lanark, Hull, and Papineau counties. Similar disjunct populations are known in the U.S. from New York State and New Hampshire. The alternative hypothesis is that the distribution of margined madtom has expanded into Canada as a result of its use as baitfish. Margined madtom is a popular baitfish in the United States and survives transportation well (Coad 1986). 

Habitat

The margined madtom prefers clear, high-gradient streams with moderate current among riffles with a boulder, rubble, or gravel substrate (Goodchild 1990). Since the publication of the previous status report, the Ontario Ministry of Natural Resources (OMNR) has captured several specimens of Noturus insignis from lakes in Muskoka County in areas with still or slow current with gravel and sand or boulder and sand substrate. As such, the habitat preferences of this fish may not be as restrictive as once thought. 

General Biology

The margined madtom is a secretive nocturnal species that hides among the rocks and boulders in rivers and streams. This fish spawns in spring or early summer but very little is known about its spawning habits. Males guard egg masses that are laid in nests located under flat rocks in gently flowing water above and below riffles. Disturbance causes guardian males to abandon or eat the eggs (Stockel and Neves 2000). Margined madtom is a benthic feeder that feeds on insects that live on the stream or river bottom. Due to its scarcity and small size, the margined madtom has not been extensively studied; little is known about its movements or migrations.

Artificial propagation of the margined madtom by egg hatching and induced spawning has been investigated as a means to recover the species (Stoeckel and Neves 2000, 2001). In captivity, optimum hatching success was obtaining by using strong agitation to tumble the eggs and high temperatures of 28-30° C. It is possible that high temperatures are required for optimum hatching success in the wild, which would restrict the distribution of this species to warmer water bodies.

Population Size and Trends

Only 49 margined madtom specimens were captured in Canada prior to 1990 (Goodchild 1990). Since this time, at least additional 64 specimens have been captured. The majority of specimens were collected from the Fall River in Lanark County and Lake Joseph in the Muskoka District, Ontario.

Since the original status report, the margined madtom has been captured at all historic locations and at several new locations in Ontario and Quebec. New locations in Ontario include Lake Muskoka and Lake Rosseau in the Muskoka District, and in Bolton Creek and the Mississippi River in Lanark County. In Quebec, the known distribution of the margined madtom has expanded into the Gatineau and Ottawa rivers. These new records of capture may be the result of increased and more rigorous sampling efforts or recent introductions.

Limiting Factors and Threats

The margined madtom is influenced by habitat change. Literature records (Coad 1986, Goodchild 1990) detail the specific habitat requirements of this species although recent captures in the Muskoka Lakes suggest that this species may have a wider tolerance than first reported. Any activity that eliminates riffle areas or slows water flow may limit their population size (Coad 1986). This fish is intolerant of silt covering the rocky substrate (Coad 1986). Siltation caused by erosion or agricultural and urban development also affects the survival of the margined madtom. Low numbers of individuals, fluctuating population sizes and a limited amount of suitable habitat restrict the population size and distribution of the margined madtom, which is at the northern limit of its range in Canada. The collection of specimens may also have contributed to the depletion of populations already low in numbers. 

Existing Protection

In Canada, there is no protection specific to the margined madtom. Fish habitat is protected by the federal Fisheries Act. The Ontario Lakes and Rivers Improvement Act provides additional protection for the habitat of this species. In Quebec, fish habitat is protected by the Environmental Quality Act.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC Membership

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Definitions

Species

Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)

A species that no longer exists.

Extirpated (XT)

A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A species facing imminent extirpation or extinction.

Threatened (T)

A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)^Footnotea

A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)^Footnoteb

A species that has been evaluated and found to be not at risk.

Data Deficient (DD)^Footnotec

A species for which there is insufficient scientific information to support status designation.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.