An Identification of the European Origins of Great Lakes Brown Trout Strains: A Phylogeographic Analysis Using Mitochondrial DNA Sequence Variation

Using the extensive knowledge of European brown trout (Salmo trutta) mitochondrial DNA control region variation, it is possible to identify which historical clades and populations have contributed to the modern Great Lakes hatchery strains. The objective of this study was two fold: to identify the European origins of Great Lakes brown trout and to compare the performance of these strains with their European assignments. A total of 60 brown trout from hatcheries in Michigan,streams in Michigan and Wisconsin, Lake Michigan and Lake Superior were given strain assignments through mtDNA ND-1 sequences and European haplogroup assignments were identified through mtDNA control region sequences. We identified two major mtDNA evolutionary lineages with a total of three haplotypes present in the sample group. The Gilchrist Creek and Seeforellen strains share a matrilineal heritage of sea run trout, except for one Seeforellen ND-1 genotype which belongs to a mtDNA control region sister lineage of river resident trout. The Wild Rose strain has matrilineal origins from a population in the Garonne River in southwest France. The three major haplogroups observed in modern Great Lakes hatcheries represent three unique evolutionary life histories and these seem to translate into variable performances in modern stocking.