** The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the author at camurphy@msu.edu or via telephone at 517-432-7771. Questions? Contact the GLFC via e-mail or via telephone at 734-662-3209 **

Estimating the sublethal effects of lamprey parasitism on lipid allocation, reproduction and population dynamics of lake trout

Cheryl Murphy², Sara Smith², Rick Goetz³, Shawn Sitar⁴

²Department of Fisheries and Wildlife, Lyman Briggs, College,

Michigan State University, 480 Wilson Road, East Lansing, MI, 48823

³NOAA Manchester Research Station, 7305 E. Beach Dr., Port Orchard, WA, 98366

⁴ Marquette Fisheries Research Station, Michigan Department of Natural Resources,

484 Cherry Creek Road, Marquette, MI, 49855

January 2013

Abstract

Sea lamprey invasion of the Great Lakes has been linked directly to lake trout population decline through parasitism mortality. Less well understood are the sublethal effects of a parasitism event on a lake trout. Current lake trout population models do not incorporate the likely decrease in growth and reproductive ability due to sublethal sea lamprey attack and may be underestimating the full effects on lake trout. This study aims to identify sublethal effects of parasitism and to determine if life history can influence such effects. We examined the effects of parasitism on the lean and siscowet lake trout morphotypes. Siscowets have higher muscle lipid levels and inhabit the depths of Lake Superior. Leans inhabit shallow waters throughout the Great Lakes and have been the focus of conservation and re-stocking efforts. Both morphotypes were subjected to sea lamprey parasitism for one to five days and analyzed for fecundity, muscle lipid levels, plasma sex steroids, gonadotropin and hepatic gene expression Field collections from Lake Superior were also collected and sampled to determine the range of responses experienced in the wild. Results showed that lake trout exhibit sublethal responses to parasitism and that endocrine, immune and bioenergetics systems are affected. Furthermore, siscowets and leans respond differently to sea lamprey parasitism; siscowets mount an immune response and sacrifice lipid storage to combat parasitism, where leans show an overt stress response and express genes related to circulatory compensation and bioenergetics. Both leans and siscowets show evidence of endocrine disruption. These sublethal effects can translate to differential population impacts for each morphotype.