February 2007
Finding Diporeia
Researchers investigate loss of prey on juvenile lake whitefish
For lake whitefish, once the mainstay of the Lake Michigan commercial fishery, the challenge of finding a nutritious meal is beginning to take a toll. Growth and body condition of lake whitefish have declined in recent years, attributed to a lake-wide decrease in their primary prey, the bottom-dwelling organism Diporeia.
Scientists suspect the loss of this high-quality food item might also be impacting juvenile lake whitefish. If adult females are producing smaller less robust eggs, their offspring may be hatching at smaller sizes, already deficient in essential fatty acids.
“It’s a concern because these young fish need to be in good condition to accumulate fat and energy during the summer months in preparation for winter,” explains Michigan Sea Grant Extension Educator Ron Kinnunen. “The number of healthy whitefish that survive the winter determines the size of next year’s population.”
Kinnunen is one of several collaborators on a Purdue University research project examining how the loss of Diporeia affects the growth and survival of juvenile lake whitefish in Lake Michigan. Funded by the Great Lakes Fishery Trust and Purdue Research Foundation, the study is looking at the role of body size, condition and composition on first-year survival of lake whitefish.
Researchers and collaborators have collected samples of whitefish eggs from several locations around Lake Michigan. Laboratory studies are investigating egg composition to determine physical condition. Investigators are also sampling adult fish for muscle and body composition.
Results of the research will contribute to our understanding of food web impacts on recruitment dynamics of lake whitefish in Lake Michigan and provide critical information necessary for improving fishery yield forecasts.
By Joyce Daniels
Project: Does Adult Body Condition Affect Recruitment Potential in Lake Whitefish (Coregonus clupeaformis)
Lead investigator: Dr. Trent Sutton, Purdue University
See: Project description
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