Seasonal abundance and movement of the invasive round goby (Neogobius melanostomus) on rocky substrate in the Duluth-Superior Harbor of Lake Superior

Despite its small size [adult: 60-130mm, total length (TL)] and limited home range, the round goby (Neogobius melanostomus) has quickly become established throughout the Laurentian Great Lakes. Little information is available, however, on the natural dispersal pattern of this species. This capture-mark-recapture study utilised alphanumeric tags subcutaneously inserted into round gobies (n=1228) along a 550-m stretch of the Duluth-Superior Harbor shoreline to observe their movement over a 13-month period. Recaptured round gobies (n=415) exhibited highly leptokurtic movement distributions, and movement events were not correlated with fish size, gender or month. Our work indicates that round gobies >50mm (TL) generally occupy an area less than the minimum sampling interval (25m); however, occasional movement up to 50m per day could facilitate range expansion in the Laurentian Great Lakes.