Genetic Analysis of Wild Lake Trout Embryos Recovered from Lake Michigan

Abstract

The Mid-Lake Reef Complex (MLRC) is a large area of deep reefs that separate the two main basins of Lake Michigan. In an attempt to evaluate which of several strains of lake trout Salvelinus namaycush stocked in Lake Michigan are actively spawning at the MLRC, eggs that had been deposited by spawning lake trout were collected at three sites on East Reef. These eggs were incubated and shown to be viable and capable of developing to the emergent fry stage. The samples were genotyped at four microsatellite loci, and a proportional admixture analysis was performed to estimate the genetic contribution of the four predominant lake trout hatchery strains used to stock the MLRC. These estimates were then compared with the abundance of each strain stocked since 1985. The point admixture estimates indicated unequal spawning success among strains in the wild. Specifically, the Seneca Lake strain appeared to be the most successful, while the Lewis Lake strain was the least successful and may not be spawning in the wild. The implications for conservation management are also discussed.