Research Document - 2010/014

Diversity and Distribution of Chars, Genus Salvelinus, in Northwestern North America in the Context of Northern Dolly Varden (Salvelinus malma malma (Walbaum 1792))

By J.D. Reist and C.D. Sawatzky

Abstract

Four (or five) species of chars occur in waters of northwestern North America – Dolly Varden, Bull Trout, Arctic Char, Lake Trout, and Angayukaksurak Char. A sixth, Brook Trout, has been introduced in southern areas but does not co-occur with the above. The taxonomic differentiation of the first three of the above species is presently mostly resolved, however, past taxonomy has submerged or confused these taxa. Thus, over time the composition of populations within these taxa has varied which results in interpretive issues for earlier literature. Dolly Varden, Angayukaksurak Char and Bull Trout are all primarily associated with riverine habitats and the first two have been synonymised; although distinct, Bull Trout appear to be a species that exhibits similar ecological preferences but will use lakes for part of its life history if available. Arctic Char and Lake Trout are associated with lacustrine environments, although both use rivers for migrations and in some cases life history. Northern Dolly Varden and Bull Trout are generally parapatric, however, limited sympatry exists in the central Mackenzie River basin. Northern Dolly Varden and Arctic Char are mostly parapatric in Canada, and the few occurrences of the latter within the geographic range of the former are restricted to unconnected lakes; Arctic Char and Bull Trout are allopatric in distribution. Lake Trout, the most widely distributed char in this area, is sympatric with all other char species, however, ecological preferences appear to restrict contact. Accordingly, although possible based upon evidence from elsewhere, there are no documented cases of hybridization among the chars of northwestern Arctic North America. There is, however, implied introgression among some.

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