HOMING AND SPATIAL USE OF GAG GROUPER, Mycteroperca microlepis By BRIAN L. KIEL A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004 Copyright 2004 by Brian L. Kiel To my parents ACKNOWLEDGMENTS I am very grateful to my wife, Patricia Mergo, for her love, patience, and support. It’s been a journey and during this work-in-progress, my two children, Casey and Kaitlyn were born. I have truly enjoyed my time spent with them as a stay-at-home father as I have come to learn about the important things in life. I would also like to thank my chairman, Dr. William J. Lindberg, for his patience, advice, constructive criticism, and offshore and financial support. Many thanks also go to the members of my committee, Drs. Debra Murie and Tom Frazer, for their patience, advice, and critical review that were necessary to help guide me to this point. I thank Dr. Chris Sistrom of the U.F. Shands Hospital, Radiology Department, for statistical advice and expertise. To Loren Kellogg, Jim Loftin, Jason Hale, and Allen Heck, I also owe a great deal of gratitude for the long field days they endured to help complete this project. Financial assistance was also provided by the Florida Fish and Wildlife Conservation Commission, Marine Resources Grants Program (Grant No. MR-073), and the National Marine Fisheries Service MARFIN Program (Grant No. NA57FF0288). iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT.........................................................................................................................x CHAPTER 1 INTRODUCTION ........................................................................................................1 2 MATERIALS AND METHODS .................................................................................8 Suwannee Regional Reef System (SRRS)....................................................................8 Study Design.................................................................................................................8 Telemetry Equipment and Tagging Methods .............................................................10 Telemetry Relocation Techniques ..............................................................................12 Gag Spatial Utilization ...............................................................................................13 Individual Displacements of Ultrasonically Tagged Gag...........................................13 Mass Displacement Experiments................................................................................14 FLOY Tagging ....................................................................................................14 Fish Traps and Trapping......................................................................................14 Mass Displacement Trials ...................................................................................15 U/W Surveys .......................................................................................................16 Statistical Analysis ..............................................................................................16 3 RESULTS...................................................................................................................19 Gag Spatial Utilization ...............................................................................................19 Hourly Tracking ..................................................................................................21 Tracking session #1......................................................................................22 Tracking session # 2.....................................................................................23 Tracking session # 3.....................................................................................24 Individual Displacements of Ultrasonically Tagged Gag...........................................25 Mass Displacement Experiments and U/W Surveys ..................................................31 Trial 1: 3000 and 4000 Meter Displacements .....................................................32 v Trial 2: 2000 and 3000 Meter Displacement.......................................................33 Combined Trials ..................................................................................................34 4 DISCUSSION.............................................................................................................61 Spatial Utilization .......................................................................................................61 Adaptive Significance.................................................................................................63 Homing Mechanisms..................................................................................................65 Fisheries Management Implications...........................................................................67 Future Work................................................................................................................68 LITERATURE CITED ......................................................................................................70 BIOGRAPHICAL SKETCH .............................................................................................79 vi LIST OF TABLES Table page 1 Marine teleosts that are believed to possess homing ability. .....................................4 2 Relocation summary of 5 gag tagged with internally placed ultrasonic tags...........19 3 Relocation summary of 9 gag tagged with externally placed ultrasonic tags. .........20 4 Gag sizes and dates tracked......................................................................................21 5 Summary of diel tracking of ultrasonically tagged gag. ..........................................22 6 Summaries of displacement distances and homing success.....................................26 7 Homing status and size of individually displaced gag. ............................................27 8 Gag displacement distances, averages and range of sizes........................................32 9 Gag size categorized by mass displaced fish from both trials..................................33 10 Parameter estimates for the significant regression equation: ...................................35 vii LIST OF FIGURES Figure page 1 Map of Florida showing the mouth of the Suwannee River ....................................17 2 A Suwannee Regional Reef System (SRRS) array. .................................................18 3 Relocations of gag # 365..........................................................................................36 4 Relocations of gag # 456..........................................................................................37 5 Relocations of gag # 338..........................................................................................38 6 Relocations of gag # 2435........................................................................................39 7 First hourly tracking session of two gag, # 2435 and # 02.......................................40 8 Second hourly tracking session of gag # 2435.........................................................41 9 Third hourly tracking session of one gag, # 15........................................................42 10 1000 meter displacement of gag # 10.......................................................................43 11 2000 meter displacement of gag # 11.......................................................................44 12 3000 meter displacement of gag # 15.......................................................................45 13 3000 meter displacement of gag #17........................................................................46 14 Relocations of gag # 01............................................................................................47 15 233 meter displacement of gag # 05.........................................................................48 16 300 meter displacement of gag # 07.........................................................................49 17 300 meter displacement of gag # 06.........................................................................50 18 450 meter displacement of gag # 08.........................................................................51 19 Relocations of gag # 08............................................................................................52 20 600 meter displacement of gag # 09.........................................................................53 viii 21 1000 meter displacement of gag # 03.......................................................................54 22 Relocations of gag # 15............................................................................................55 23 Relocations of gag # 17............................................................................................56 24 4000 meter displacement of gag # 13.......................................................................57 25 4000 meter displacement of gag # 18.......................................................................58