Populations at the edge of their range often invoke taxonomic confusion and are increasingly considered to harbour cryptic genetic diversity of significant adaptive potential. In the Peace River region of northwestern Canada, three sculpin species have been reported: spoonhead (Cottus ricei), slimy (Cottus cognatus) and prickly (Cottus asper) sculpin. Prickly sculpin occurrence in this region represents the most eastern edge of its distribution, but its status has remained uncertain following its initial discovery in 1989. These populations may represent an independently evolving lineage of special conservation concern, or be the consequence of an ongoing range expansion, possibly accompanied by interspecific hybridization with local species. Using a combination of mtDNA sequencing and microsatellite analyses, we did not find peripheral population differentiation or interspecific hybridization, suggesting that the Albertan Peace River population belongs to the same genetic group as its western counterparts. Future studies will benefit from a greater understanding of whether demographically independent prickly sculpin populations established in Alberta without the typical genetic signatures of expansion at the periphery of their range.