Mitochondrial DNA Variation among Lake Trout (Salvelinus namaycush) Strains Stocked into Lake Ontario

Abstract

Mitochondrial DNA (mtDNA) variation was examined in 492 fish representing six lake trout (Salvelinus namaycush) strains used for stocking and restoring populations in Lake Ontario. mtDNA was extracted from 432 fish by a total DNA isolation protocol (CTAB). mtDNA was also extracted from 60 additional fish using the purification method of CsCl ultracentrifugation. The more rapid CTAB protocol made feasible analysis of sample sizes (n ≥ 80 per strain) required as baseline data for future mixed-stock analysis (MSA). Restriction enzymes AvaI, BamHI, HinfI, and TaqI resolved seven mtDNA haplotypes and were used to characterize fish from each of six strains (Clearwater, Jenny, Killala, Manitou, Seneca, and Superior). Frequencies of these haplotypes were significantly different among the six strains (p < 0.001). Differences between haplotype frequencies of the Killala and Superior strains were striking and permit greater discrimination of these strains than allozyme data. The level of differentiation observed among strains indicates that mtDNA haplotype information will enhance the ability of MSA to determine the hatchery strains that serve as parents to lake trout fry collected from Lake Ontario.