Sympatric Occurrence of Two Species of Humpback Whitefish in Squanga Lake, Yukon Territory

• Published in: Journal of the Fisheries Research Board of Canada
• Main Author: Lindsey, C. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1963
• Subjects: General Medicine; Yukon; Squanga Lake; Coregonus pidschian; Humpback whitefish; pidschian; Yukon river
• Online Access: http://dx.doi.org/10.1139/f63-050; http://www.nrcresearchpress.com/doi/pdf/10.1139/f63-050

Squanga Lake in the Canadian headwaters of the Yukon River contains two species of humpback whitefish, characterized by modal first arch gill raker counts of 23 and 28 but with overlap in the range of counts. The species can be separated more sharply by raker counts of the second arch, also with modes of 23 and 28. Seven other morphometric characters not correlated with gill raker count each have significantly different means, but some overlap, between the species.In June the species with high raker count mainly occupies the pelagic zone, while the low count species occupies the bottom layers at all depths. The high count species feeds mainly on plankton, the low count species on bottom organisms. The high count species spawns in inlet and outlet streams in November and December. Gonad development in June suggests that the low count form spawns later, in localities unknown. Samples from early winter spawning runs contained exclusively high count individuals. A few fish, probably hybrids, had raker count corresponding to one species and most other morphological characters corresponding to the other. Tentative names for the species are Coregonus clupeaformis (high gill raker count) and Coregonus pidschian.