Science Advisory Report  2013/044

Advice on taxonomic validity and designatable units of Shortjaw Cisco (Coregonus zenithicus) populations in Canada

Summary

• A morphological taxonomic approach does not generally work for new world ciscoes throughout their range; however, for the Great Lakes and Lake Nipigon, it has historical validity.
• The risk of diversity loss following the standard taxonomic approach is very high.
• A species-flock approach will likely result in more complete and representative delineation of DUs, thus facilitating more accurate conservation assessments.
• Shortjaw Cisco is only one of the nominate new world ciscoes to which this advice is applicable – the advice and approach applies generally in situations where multiple cisco forms occur and appear to have been derived through sympatric evolutionary processes.
• Application of the approach is required on a waterbody-specific basis.
• A weight-of-evidence approach including as many aspects of cisco biology as possible is recommended (e.g., morphology, ecology, biology or life history, genetics).
• Based on present knowledge, the application of this approach to new world cisco diversity explicitly results in 15 designatable units; more are likely as evidence accrues.
• Investigation of the applicability of the species-flock approach to similar situations in other taxonomic groups may extend its general utility (e.g., sticklebacks, whitefishes).
• This approach may facilitate the application of ecosystem-based management and analyses of threats to cisco biodiversity (detailed analyses of threats was not conducted as part of this analysis).

This Science Advisory Report is from the October 30-31, 2012 pre-COSEWIC assessment for Shortjaw Cisco. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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