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COSEWIC Assessment and Update Status Report on the Blackfin Cisco in Canada

Special Significance of the Species

Of the six cisco species identified as endemic to the Laurentian Great Lakes and Lake Nipigon by Koelz (1929), the blackfin cisco is one of only three species (other species are C. hoyi and C. zenithicus) known to be extant in Lake Nipigon. The ciscoes are the most notable of the few species endemic to the relatively young waterbodies of northern North America, and are believed to be one of few examples of the incipient species flock concept in North America (Smith and Todd 1984). As endemic species, these ciscoes represent unique evolutionary and ecological processes. The Laurentian Great Lakes and Lake Nipigon are no more than 18 000 years old (Dyke and Prest 1987); therefore, the endemic ciscoes have likely evolved in the Great Lakes and Lake Nipigon within the last 18 000 years (Smith and Todd 1984). Changes in gill raker morphology (e.g. number, length) over time, have minimized competition between the endemic ciscoes (Smith and Todd 1984). In addition to these unique processes shared by the endemic ciscoes, the blackfin cisco exhibits unique adaptations to its deepwater habitat.

The deepwater ciscoes were once a commercially important species in the Great Lakes and several species, including blackfin cisco, are still harvested in Lake Nipigon.