One of the key areas of research at the Great Lakes Science Center is lake trout. Fishery regulations, sea lamprey control, and stocking of hatchery-raised lake trout are methods that have been used to restore the lake trout in waters where they once thrived. In most areas, lake trout have failed to produce recruits, and populations are sustained entirely by planting of hatchery fish. In a few other areas (mostly in Lake Superior), populations consist of both wild and hatchery fish. Researchers study the population dynamics of lake trout in the Great Lakes with an emphasis on understanding fundamental processes that contribute to the long-term sustainability of this species. Some of the current research focuses on the following:

Analysis of survival rates of the Gull Island Shoal Population. The population of wild and hatchery lake trout near Gull Island Shoal, Lake Superior, has been studied since the 1960s. It is one of the few remaining self-sustaining populations of lake trout in the Great Lakes. A mark-recapture experiment to estimate survival rates of lake trout in the Gull Island Shoal area has been ongoing since 1969. This study is evaluating the effect of critical factors such as sex, age, and hatchery origin on changes in survival rates. The efficacy of various management practices (such as the establishment of a refuge) will be determined by quantitatively describing changes in survival rates of this population in response to management regulations.

Analysis of annual survival rates of the lake trout population in northwestern Lake Michigan. Models developed by scientists from the Biological Resources Division were applied to data collected from this group of fish in Lake Michigan. Annual survival rates have been increasing since 1987, coinciding with increased regulations to protect lake trout. Even though annual survival rates of adult fish exceeded the minimum rate deemed necessary for self-sustaining lake trout populations, scientists concluded that adult survival rates alone are not an adequate criterion for restoration of lake trout. This is because the abundance of this group of fish has been declining in the last few years. Researchers believe that these declines were due to decreased recruitment of young fish to the adult population and have recommended that future studies of this population focus on survival rates from time of stocking to age 6.

Performance characteristics such as behavior, physiology, biochemistry, egg quality, morphology, survival, genetics, and reproductive success have been shown to differ between hatchery-reared and wild fish. Researchers are conducting a comprehensive review of literature for lake trout and other salmonine species comparing the performance of hatchery-produced fish with that of wild fish. The products from this work will serve as useful information resources for researchers and resource managers concerned about possible dysfunctional effects of hatchery rearing and appropriate measure that might mitigate such effects.