Shortjaw cisco COSEWIC assessment and status report: chapter 5

Distribution

While best known from the Great Lakes, shortjaw ciscoes have a widespread distribution throughout central Canada, as well (Figure 2). Shortjaw ciscoes were last verified in Lake Michigan in 1975 and Lake Huron in 1982 (Todd 1985). However, these fish could have been strays from Lake Superior where the species was still reasonably abundant (Ono et al. 1983). Reports of the longjaw cisco, C. alpenae, in Lake Erie (Scott and Smith 1962) should be attributed to C. zenithicus based on re-examination of the original specimens and the findings of Todd et al. (1981) that concluded C. zenithicus and C. alpenae were conspecific. Interestingly, the species was not known from Lake Ontario (Koelz 1929).

Other than the Great Lakes, shortjaw ciscoes have been reported from at least 22 lakes in Canada extending from Ontario to the Northwest Territories (Table 1; Clarke 1973; Houston 1988; Etnier and Skelton 2002; Murray and Reist 2003). Most of these identifications were likely based on the key characteristic of low gill raker counts (especially when sympatric pairs of forms were present) and could represent more than one species (Clarke 1973). However, these records appear to be valid, although Clarke’s suggestion that the species should be renamed C. prognathus based on nomenclatorial priority has been invalidated (Todd 1981a).

Figure 2. Distribution of known populations of the shortjaw cisco in North American lakes (dots).

Figure 2. Distribution of known populations of the shortjaw cisco in North American lakes (dots).

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