Mitochondrial DNA Diversity among Broodstocks of the Lake Trout,Salvelinus namaycush

Abstract

Mitochondrial DNA was purified from 151 lake trout (Salvelinus namaycush) representing nine brood stocks along with an additional 30 fish from two natural populations. Eighteen restriction endonucleases were employed to analyze 126 brood stock fish. Two of these enzymes (Hind III and Bam HI) were used to examine the fish from the natural populations (Hare Island (Lake Superior) and North Knife Lake (Manitoba)) and the remaining brood stock samples from the Manitou (12 fish) and Seneca (13 fish) strains. The mitochondrial genome of the lake trout was 16 800 ± 200 base pairs in length. A single heteroplasmic individual was discovered in the Manitou strain. It contained two genomes, the less frequent of which was 20 base pairs shorter than the other. The 18 restriction enzymes resolved 13 mitochondrial clones which fell into three major groups. These clonal groups, which can be identified by their Bam HI restriction phenotypes, have a specific distribution: a western Great Lakes group, a central Great Lakes group, and an eastern Great Lakes group. Seven mitochondrial clones were unique to a particular stock. In addition there were dramatic shifts in the relative proportions of the six remaining mitochondrial clones among the brood stocks. These results indicate that mitochondrial DNA markers have great potential for the identification and management of lake trout strains.