MITOCHONDRIAL-DNA VARIATION AMONG LAKE TROUT (SALVELINUS-NAMAYCUSH) STRAINS STOCKED INTO LAKE-ONTARIO

Mitochondrial DNA (mtDNA) variation was examined in 492 fish represent ing six lake trout (Salvelinus namaycush) strains used tor stocking an d restoring populations in Lake Ontario. mtDNA was extracted from 432 fish by a total DNA isolation protocol (CTAB). mtDNA was also extracte d from 60 additional fish using the purification method of CsCl ultrac entrifugation. The more rapid CTAB protocol made feasible analysis of sample sizes (n greater-than-or-equal-to 80 per strain) required as ba seline 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 haplot ypes were significantly different among the six strains (p < 0.001). D ifferences between haplotype frequencies of the Killala and Superior s trains were striking and permit greater discrimination of these strain s than allozyme data. The level of differentiation observed among stra ins indicates that mtDNA haplotype information will enhance the abilit y of MSA to determine the hatchery strains that serve as parents to la ke trout fry collected from Lake Ontario.