Abstract
The trophic linkage between yellow perch Perca flavescens and two exotic prey items, alewife Alosa pseudoharengus and round goby Neogobius melanostomus , was investigated in the extreme southern area of Lake Michigan during the summer of 2002. Yellow perch ≥100 mm total length, L T ( n = 1293) exhibited size selective feeding, with 148 fish containing round gobies and 120 fish containing alewives. The mean round goby L T , preyed on by yellow perch, was 23% of the predator L T , with a range of 7 to 47%, and mean alewife L T was 32% of yellow perch L T , with a range of 18 to 46%. Although the selection of prey size by yellow perch increased proportionally with yellow perch L T , prey consumed appeared smaller than theoretically possible based on gape size.