Round Goby-Induced Changes in Young-of-Year Yellow Perch Diet and Habitat Selection

................................................................................................................. ii TABLE OF CONTENTS .................................................................................................. v LIST OF FIGURES ....................................................................................................... vii LIST OF TABLES .......................................................................................................... ix ACKNOWLEDGEMENTS ............................................................................................... x Introduction ............................................................................................................... 1 Lake Michigan’s rocky habitat and associated benthic community ............................... 4 Yellow perch in Lake Michigan ....................................................................................... 7 Round gobies in Lake Michigan ...................................................................................... 9 Objectives and overview ............................................................................................... 11 Methods .................................................................................................................. 15 Hypothesis 1: Effect of round gobies on age-0 yellow perch habitat utilization ......... 15 Hypothesis 1Statistical methods ................................................................................ 21 Hypothesis 2: Effect of round gobies on benthic invertebrate abundance ................ 22 Hypothesis 2 Statistical Methods ............................................................................... 23 Hypothesis 3: Effect of round gobies on age-0 yellow perch diet ............................... 24 Hypothesis 3 Statistical Methods ............................................................................... 25 Hypothesis 4: Yellow perch growth has decreased as a result of increasing round goby abundance in western Lake Michigan .......................................................................... 30 Results ..................................................................................................................... 31 Hypothesis 1: Effect of round gobies on age-0 yellow perch habitat utilization ... 31 Hypothesis 2: Effect of round gobies on benthic invertebrate abundance ................. 35 Hypothesis 3: Effect of round gobies on age-0 yellow perch diet ................................ 38 Hypothesis 4: Decrease in growth of yellow perch with increasing round goby abundance .................................................................................................................... 47 Discussion ................................................................................................................ 49 Exploitative competition between age-0 yellow perch and round gobies................... 53 Variation in prey distribution and stomach contents of yellow perch ......................... 56 Interference competition between age-0 yellow perch and round gobies ................. 59 Age-0 yellow perch predation on round gobies ........................................................... 61 The future of yellow perch in Lake Michigan ............................................................... 64 Future directions ........................................................................................................... 66 Literature Cited ........................................................................................................ 68