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, [email protected]
Jacques Rinchard, The College at Brockport, State University of New York, [email protected]
Austin Happel, John G. Shedd Aquarium, [email protected]
Matthew Kornis, U.S. Fish and Wildlife Service, [email protected]
Tomas Hook, Purdue University, Dept. Forestry and Natural Resources, [email protected]
Harvey Bootsma, University of Wisconsin-Milwaukee, [email protected]
Benjamin Turschak, Michigan Department of Natural Resources, [email protected]
Charles R. Bronte, US Fish and Wildlife Service, [email protected]

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.