Andrea Koster ACF Abstract FY11

"Diet of Round Gobies in coastal areas of Lake Michigan"

Conference Name: Midwest Fish and Wildlife Conference

The round goby (Neogobius melanostomus) is a species native to the Ponto-Caspian region of Eurasia that was introduced to the Great Lakes in the early 1990’s and has since undergone rapid expansion. The round goby is known to consume a variety of prey items from soft-bodied invertebrates to hard-bodied prey such as dreissenid mussels, primarily based on the round goby’s habitat use and body size. We hypothesized that round goby: (1) abundance is greater at pierheads than adjacent drowned river mouth (DRM) lakes (which have direct connections to Lake Michigan) because of differences in substrate between the two habitats, and (2) diets at pierheads are primarily comprised of dreissenid mussels based on the size of round gobies and density of dreissenids in the two habitats.  To test these hypotheses, we sampled round gobies with baited minnow traps at six sites (consisting of pierhead and adjacent DRM-lake habitats). As predicted, we found significantly higher densities at pierheads compared to the DRM lake habitats. Stomach content analysis was conducted on each sampled specimen by separating the prey types into major taxonomic groups and assessing differences in prey consumption as a function of total prey volume. The results from this study will allow a more thorough understanding of round goby population distribution and habitat use in coastal areas of Lake Michigan.

Andrea Koster, Yakuta Bhagat, and Carl Ruetz