. The Canadian field-naturalist. 1989 PARKER: STATUS OF THE BLACK REDHORSE 177 CaMecUon SMm iUHHZ University of Michigan Museum Zoology 4Wilfred Launer University Museum. Figure 3. Collection records of Moxostoma duquesnei in Ontario. a tributary to Lake Huron, and then from the Grand River system (Kott et al. 1979) and the Thames River watershed (Gartner Lee Associated 1981). Self-sustaining populations are known only from the Thames and Grand river systems. The Grand River population has been most studied. Adults and juveniles have been reported at several sites on the upper Grand River near
. The Canadian field-naturalist. 1989 PARKER: STATUS OF THE BLACK REDHORSE 177 CaMecUon SMm iUHHZ University of Michigan Museum Zoology 4Wilfred Launer University Museum. Figure 3. Collection records of Moxostoma duquesnei in Ontario. a tributary to Lake Huron, and then from the Grand River system (Kott et al. 1979) and the Thames River watershed (Gartner Lee Associated 1981). Self-sustaining populations are known only from the Thames and Grand river systems. The Grand River population has been most studied. Adults and juveniles have been reported at several sites on the upper Grand River near Elmira and in the Nith River southwest of the city of Cambridge. These two population sub-units are small and are limited to specific river sections having suitable habitat. This species is rare even at population centrums; approximately 1 in 10 redhorse suckers collected are Black Redhorse. Although a finite population estimate has not been formulated, observations from this population between 1977 and 1982 suggest a downward trend in population size. As a result, the collection of specimens for scientific study was curtailed in 1982 in an effort to avoid possible impact on the population. The Thames River Black Redhorse population is little known. Gartner Lee Associated (1981) first reported this species in the Thames River on the basis of several juvenile specimens. A small collection of breeding adults was made near the original capture site in 1982. No other specimens have been reported. This population is believed even smaller than the Grand River population. Attempts to confirm the continued presence of this species in the Maitland River have proven unsuccessful. Surveys in 1980, 1981 and 1982 for the express purpose of collecting Black Redhorse in this watershed failed. The origins of the Black Redhorse populations are unknown; however, a review of collection and population data suggests that the Grand River population may have served as the source for the populations
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