Fall migration of round goby in Lake Michigan near Milwaukee, Wisconsin

Session: Invasive Species (3)

Erik Carlson, University of Wisconsin-Milwaukee, [email protected]
John Janssen, John Janssen, [email protected]

Abstract

The offshore migration habits of the invasive Round Goby (Neogobius melanostomus) in Great Lakes is based on anecdotal information. When Round Goby move offshore, they have the potential to become prey items for fishes like Lake Trout, Burbot, and Brown Trout. Due to the Round Goby’s preference for rocky habitat, it is difficult to sample using traditional methods, such as trawls. To better understand this movement, and the factors that drive it, a remotely operated vehicle (ROV) equipped with a tracking system was used to observe the number of fish along transects, and to collect specimens for diet and aging purposes. In this study, six ROV transects per site were taken at depths of 10 meters to 40 meters in 10 meter increments. Initial observations showed more goby nearshore (10 m site) in September (1.71 fish per transect meter) and decreasing to 0.15 fish per meter, while at 30 m abundance increased from 0.03 fish per meter to 0.41 fish per meter by the end of October. A 2-Factor ANOVA, with depth and time of year as the two factors, showed significant results for the interaction between depth and time of year.