[1] All Coregonus species are protected under appendix III of the Bern Convention,[2] and Annex IV of the EC Habitats Directive (92/43/EEC)[3] Phylogenetic evidence indicates that the most basal member of the genus is the highly endangered Atlantic whitefish (C. huntsmani), which is endemic to a single river basin in Nova Scotia, Canada.

A drastic increase in number of recognized species occurred in 2007, when a review advocated that more than 50 local European populations should be considered as distinct based on morphological differences.

[13] A review of whitefish in the United Kingdom found that the identification key provided in 2007 did not match most individuals and that solid evidence for more than one species in that region is lacking.

[9] The morphs or clinal species may rapidly disappear (in 15 years or less, equalling three Coregonus generations) by merging into a single in response to changes in the habitat.

[15] A similar pattern can be seen in North America where the ciscoes of the Coregonus artedi complex in the Great Lakes and elsewhere comprise several, often co-occurring morphs or ecotypes, whose taxonomic status remains controversial.