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COSEWIC Assessment and Update Status Report on the Margined Madtom (Noturus insignis) in Canada

Population Sizes and Trends

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

Biologists have returned to the original locations and several of the new locations of capture in Ontario and Quebec in an attempt to determine the status of the margined madtom in Canada.  During July 1982, biologists returned to the Fall River, Lanark County, to collect the margined madtom with a seine net, but their sampling attempts were unsuccessful.  However on 4 September 1997, 24 specimens where captured at this location by the OMNR with the use of a backpack electrofisher.  Three of these specimens are catalogued in the Royal Ontario Museum (ROM) collection [ROM 70989]; the remainder were released.  The use of a backpack electrofisher may have been a more effective type of sampling gear for this location (Alan Dextrase, OMNR, personal communication).  There have been no new data on the margined madtom in the Fall River since last observed there in 1997.

Between 1991 and 1996 in the Muskoka District, OMNR captured 18 margined madtom specimens in Lake Joseph [ROM 68174], 5 in Lake Muskoka [ROM 68167], and one margined madtom in Lake Rosseau (Alan Dextrase, OMNR, personal communication), as part of their smallfish survey (most caught) and near-shore index netting program.  Minnow traps were used for the smallfish survey and 6’ trap nets were used for the near-shore index netting survey.  It is suspected that this species is now established in the Muskokas as it has been captured regularly (Alan Dextrase and Warren Dunlop, OMNR, personal communication).  Elsewhere in Ontario, scientists from the OMNR returned to Bolton Creek, Hamlet of Fallbrook, Lanark County, on 4 September 1997 and two specimens were captured [ROM 70988].

In Quebec, biologists returned to the stream draining Lac à la Loutre to Lac Lapêche in Gatineau Park, where the margined madtom was originally captured in 1971.  The area was re-sampled in 1982, 1983, and 1984; these efforts did not result in the collection of this species, although in 1982, two specimens were captured further upstream [NMC 82-0321].  On 1 September 1982, two margined madtoms were captured in Rivière Lapêche, Saint-Louis-de-Masham, Gatineau County [NMC82-0572], and another was collected on 19 July the following year [NMC83-0S35].  Several specimens were captured in this area during the early 1990s (Brian Coad, Canadian Museum of Nature, personal communication).

Population sizes of the margined madtom may fluctuate due to low numbers of individuals and their dependence on the spawning success of the previous year.  These fluctuations may be evident in the Fall River, Ontario.  Fourteen specimens were captured in 1976 but, none were captured at the same site in 1982 (Coad 1986).  In 1997, 24 specimens were captured [ROM70989].  However, these differences may also be explained by the use of different sampling gear.

In the original status report, it was reported that 49 margined madtom specimens were captured prior to 1990.  Since this report, at least 64 specimens have been captured in Ontario and Quebec.  The margined madtom has been captured in four new locations in Ontario in Lake Muskoka and Lake Rosseau in the Muskoka District, and in Bolton Creek and the Mississippi River in Lanark County.  In Quebec, the distribution of the margined madtom has expanded into the Gatineau and Ottawa Rivers, Hull and Papineau County and also into the Cole Lake area in Buckingham County.  It is possible that these new records of capture may be the result of increased and more rigorous sampling efforts or recent introductions.