Nekton of Sarasota Bay and a Comparison of Nekton Community Structure in Adjacent Southwest Florida estuaries T.C. MacDonald; E. Weather; P.W., Stevens; R.H. McMichael, Jr. Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute 100 Eighth Avenue Southeast St. Petersburg, Florida 33701-5095 Prepared for Sarasota Bay Estuary Program 111 S. Orange Avenue, Suite 200W Sarasota, Florida 34236 Draft, July 21, 2010 TABLE OF CONTENTS TABLE OF CONTENTS ................................................................................................................................. i LIST OF FIGURES ........................................................................................................................................ iii LIST OF TABLES .......................................................................................................................................... v ACKNOWLEDGEMENTS ............................................................................................................................ vii SUMMARY ................................................................................................................................................... ix INTRODUCTION ........................................................................................................................................... 1 METHODS .................................................................................................................................................... 2 Study Area ................................................................................................................................................ 2 Sampling Design ....................................................................................................................................... 3 Gear Specifications and Deployment ....................................................................................................... 6 Sample Processing ................................................................................................................................... 7 Nekton Community Analysis ..................................................................................................................... 9 Bray-Curtis similarity calculation ........................................................................................................ 10 Non-metric multidimensional scaling (MDS) and Similarity Percentage Analysis (SIMPER) ............ 10 Mercury Content Analysis ....................................................................................................................... 13 RESULTS and DISCUSSION ..................................................................................................................... 15 Physiochemical conditions ...................................................................................................................... 15 Composition of overall nekton community .............................................................................................. 20 Shallow water habitats sampled with 21.3-m seines .......................................................................... 21 Nearshore habitats sampled with 183-m seines ................................................................................ 26 Nearshore habitats sampled with 183-m seines ................................................................................ 26 Deeper-water habitats sampled with 6.1-m trawls ............................................................................. 29 Species Profiles ...................................................................................................................................... 33 Pink shrimp, Farfantepenaeus duorarum ........................................................................................... 35 Blue crab, Callinectes sapidus ........................................................................................................... 39 Ladyfish, Elops saurus ....................................................................................................................... 41 Bay anchovy, Anchoa mitchilli ............................................................................................................ 43 Common snook, Centropomus undecimalis ...................................................................................... 45 Gag, Mycteroperca microlepis ............................................................................................................ 47 Gray snapper, Lutjanus griseus ......................................................................................................... 49 Pinfish, Lagodon rhomboides ............................................................................................................. 53 Sheepshead, Archosargus probatocephalus ..................................................................................... 59 Spotted Seatrout, Cynoscion nebulosus ............................................................................................ 63 Striped mullet, Mugil cephalus ........................................................................................................... 65 Nekton Community Structure .................................................................................................................. 69 Intrabay Comparison .......................................................................................................................... 69 Interbay Comparison .......................................................................................................................... 76 i Mercury Content Analysis ....................................................................................................................... 85 Ladyfish, Elops saurus ....................................................................................................................... 87 Common Snook, Centropomus undecimalis ...................................................................................... 89 Sheepshead, Archosargus probatocephalus ..................................................................................... 91 Gray Snapper, Lutjanus griseus ......................................................................................................... 93 CONCLUSION ............................................................................................................................................ 95 Physiochemical conditions ...................................................................................................................... 95 Composition of overall nekton community .............................................................................................. 95 Nekton Community Structure .................................................................................................................. 96 Mercury Content Analysis ....................................................................................................................... 97 LITERATURE CITED .................................................................................................................................. 99 APPENDICES ........................................................................................................................................... 109 Appendix A. Animals designated as Selected Taxa because of their commercial or recreational importance. ........................................................................................................................................... 111 Appendix B. Summary of species collected, by sampling event (bi-monthly), during Sarasota Bay stratified-random sampling, June 2009 to April 2010 ........................................................................... 113 Appendix C. Summary of species collected, by gear and stratum, during Sarasota Bay stratified- random sampling, June 2009 to April 2010. ......................................................................................... 119 Appendix D. Summary of species collected, by embayment, during Sarasota Bay stratified-random sampling, June 2009 to April 2010. ...................................................................................................... 125 Appendix E. Catch overview plots for dominant taxa (≥40 animals collected and ≥10 occurrence in a gear type) collected with 21.3-m seines. .............................................................................................. 131 Appendix F. Species overview plots for dominant taxa (≥40 animals collected and ≥10 occurrence in a gear type) collected with183-m seines. ................................................................................................ 155 Appendix G. Species overview plots for dominant taxa (≥40 animals collected and ≥10 occurrence in a gear type) collected with 6.1-m trawls. ................................................................................................. 173 ii LIST OF FIGURES Figure 1.Sampling sites by gear, and zone boundaries for Sarasota Bay .................................................... 5 Figure 2.Sampling areas and sample sites along Florida‘s southwest coast. ............................................ 12 Figure 3. Temperature and total rainfall during the study period (May 2009 to April 2010) and during a longer-term reference period (January 1990 to April 2010) ................................................................