Relationships between habitat characteristics and round goby abundance in Lakes Michigan and Huron

Expanding round goby (Neogobius melanostomus) populations threaten many native species throughout the Great Lakes. The qualities that make a habitat suitable for round gobies are oftentimes considered as single factors (e.g., substrate type or dreissenid mussels). A more thorough understanding of the environmental characteristics related to round goby abundance can help identify habitats that are less susceptible to invasion. This study examined the habitat characteristics associated with round goby abundance in the Beaver Archipelago of Lake Michigan and the Les Cheneaux and Saginaw Bay regions of Lake Huron. Chemical and physical variables, zooplankton, macroinvertebrate, and fish assemblages were sampled from open water and wetland habitats. Gradients in habitat characteristics, determined using ordination analyses and diversity indices, were correlated with round goby catch per unit effort (CPUE) using fyke nets. Round goby CPUE in the Beaver Archipelago was positively related to increasing productivity and a more diverse fish community. Round goby CPUE at Les Cheneaux was related to wave disturbance and fish species associated with greater habitat complexity, though habitat type alone did not explain these relationships. In contrast, round goby CPUE in highly productive Saginaw Bay wetlands was very low where fish diversity was high and assemblages were dominated by littoral species tolerant of eutrophic conditions. Overall, CPUE was related to indices of biological productivity, with the direction of these relationships varying among regions. Areas with high productivity, including some wetlands, may be less hospitable for round gobies and could serve as refugia for native species.