Subpopulation Status of Lake Whitefish (Coregonus clupeaformis) in Lake Winnipeg

Abstract

Spawning lake whitefish in Lake Winnipeg from Dauphin River–Lake St. Martin, Traverse Bay, Berens River–Poplar River–Big Black River and Grand Rapids and in Little Playgreen Lake are accorded subpopulation status based on morphometric measurements, meristic counts, and differences in frequencies of alleles at the muscle glycerol-3-phosphate dehydrogenase (g-3-pdh-b) locus. The frequency of the g-3-pdh-b-3 allele in samples from Dauphin River–Lake St. Martin was 0.77 compared with 0.46 for whitefish from the remainder of Lake Winnipeg and Little Playgreen Lake. Two loci for isocitrate dehydrogenase and one lactate dehydrogenase locus are also polymorphic in these fish but no significant allele frequency differences were found at these loci among the samples of spawners compared above. Hatchery-reared lake whitefish, obtained from stock in Clearwater Lake and William Lake and planted as fry or eyed eggs in Lake Winnipeg at Dauphin River and Grand Rapids, do not appear to have made a detectable genetic contribution to the local whitefish stocks, based on differences in g-3-pdh-b and idh Bβ allele frequencies among parent stock and spawners captured near the release sites.