Biochemical markers aid in tracing food-web interactions in the Great Lakes

Session: Exploring Predator-Prey Relationships and Feeding Ecology in the Great Lakes (4)

Sergiusz Czesny, University of Illinois, Illinois Natural History Survey, czesny@Illinois.edu
Jacques Rinchard, The College at Brockport, State University of New York, jrinchar@brockport.edu
Austin Happel, John G. Shedd Aquarium, ahappel@sheddaquarium.org
Matthew Kornis, U.S. Fish and Wildlife Service, matthew_kornis@fws.gov
Tomas Hook, Purdue University, Dept. Forestry and Natural Resources, thook@purdue.edu
Harvey Bootsma, University of Wisconsin-Milwaukee, hbootsma@uwm.edu
Benjamin Turschak, Michigan Department of Natural Resources, TurschakB1@michigan.gov
Charles R. Bronte, US Fish and Wildlife Service, charles_bronte@fws.gov

Abstract

Foraging habits of recreationally important salmonids within the Laurentian Great Lakes are relatively unknown since invasive Round Goby have become a numerically dominant prey resource. To this end, we assessed diet compositions of salmonine species from Lake Michigan using direct observations (stomach dissections) and biochemical (fatty acids) methods. Generally, we noted that some species (Chinook Salmon) specialize on Alewife, while others (brown trout and lake trout) are able to take advantage of alternative prey resources, including Round Goby, especially as they attain larger sizes. We also observed a potential for a gear bias in the stomach content of angler caught Rainbow Trout. Further analyses include investigations into spatial, temporal, and size related differences in foraging of salmonine species.