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Margined Madtom

Margined madtom

NH Conservation Status: Not listed

 

State Rank: Exotic

 

Scientific Name: Noturus insignis

 

Distribution: The margined madtom is native to rivers and streams on the eastern slope of the Appalachian Mountains from New York south to Georgia. Its range also includes margined madtom the St. Lawrence River watershed and the southeastern drainages of Lake Ontario. In New Hampshire, margined madtoms are found in southern Merrimack River tributaries and coastal watersheds.

 

Description: A small species of catfish with blue eyes and an adipose fin that is fused to the caudal fin. Yellowish to grey in color, margined madtoms are lighter in appearance than the usually darker colored bullheads.

 

Species commonly confused with: Brown bullhead, yellow bullhead

 

Madtom

The streamlined shape of the margined madtom is an adaptation for living in faster flowing rivers and streams than those preferred by other members of the catfish family in New Hampshire.

Habitat: Margined madtoms live in rocky sections of medium sized streams and small rivers, where they can be locally very abundant.

 

Life History: Female madtoms lay clusters of eggs under stones in the quiet sections of riffles, after which the eggs are defended by the males. Madtoms feed on invertebrates living in the spaces between rocks and boulders. They are considered moderately tolerant of pollution. The pectoral spines of margined madtoms contain a venom gland capable of causing a painful sting. The species was likely introduced into New Hampshire due to its past use as a bait fish. The use of margined madtom as bait is now illegal.

 

Origin: Likely introduced

 

Conservation/Management: Margined madtoms have a relatively restricted distribution and are considered vulnerable to extirpation in New York, Virginia, and Georgia. Populations in the St. Lawrence drainage are listed as critically imperiled. Margined madtoms in New Hampshire appear to be expanding their range. Margined madtoms often share habitat with longnose dace in New Hampshire. The level of competition between the two species is not well understood. The shallow riffle habitat in which these species occur is vulnerable to flow alteration due to water withdrawal or increased impervious surfaces in a watershed. Changes in the relative abundance of margined madtoms versus longnose dace may be used as a potential indicator for identifying watersheds with altered flow regimes.

 

Recommendations:

 

  • Continue to collect baseline data on the distribution and status of margined madtom and other freshwater fish species throughout New Hampshire.
  • Research the relationship between altered flow regimes and the distribution and relative abundance of margined madtoms and longnose dace in watersheds where they coexist

 

Distribution Map: (under construction)