EVALUATIONS OF GROWTH AND HABITAT USE BY GUADALUPE BASS AT A RIVERSCAPE SCALE IN THE SOUTH LLANO RIVER, TEXAS by Jillian Groeschel, B.S. A Thesis In Wildlife, Aquatic, and Wildlands Science and Management Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the requirements for the Degree of MASTER OF SCIENCE Approved Timothy B. Grabowski, Ph.D. Chair of Committee Shannon K. Brewer, Ph.D. Gary P. Garrett, Ph.D. Dr. Dominick Joseph Casadonte, Jr. Interim Dean of the Graduate School December, 2013 Copyright 2013, Jillian Groeschel Texas Tech University, Jillian Groeschel, December 2013 ACKNOWLEDGMENTS I thank the entire staff and faculty of the Department of Natural Resources Management and the Texas Cooperative Fish and Wildlife Research Unit at Texas Tech University for their guidance and support during my time as a graduate student. Specifically, I thank my major advisor, Dr. Timothy Grabowski, for providing project funds as well as constantly being available to support, guide, and direct me throughout my master’s project. I am also grateful for my committee members, Drs. Shannon Brewer and Gary Garrett. Without their support and helpful advice, this project would not have been possible. I thank the staff, and especially Karen Lopez and Robert Stubblefield at the Texas Tech University-Junction Campus for their kind words, flexibility, and hospitality during my stays in Junction, Texas. I thank Dr. Tom Arsuffi, Scott Richardson, and those from the South Llano Watershed Alliance for their knowledge of the area and people, support, and assistance. I am grateful for Carl Kittel and the staff at the A.E. Wood State Fish Hatchery for donating Guadalupe bass fingerlings for this project as well as the entire staff at the Heart of the Hills Fisheries Science Center, specifically Bobby Wienecke and Bob Betsill, for caring for those fingerlings until I was ready to tag and release them. I also thank Tim Birdsong for his involvement and knowledge as well as allowing funding for this project. The completion of this thesis would not have been possible without the assistance of several volunteers. I thank P. Bean, B. Cheek, Q. Chen, C. Craig, C. Holmes, K. Linner, J. Mueller, B. Perkins, B. Skipper, M. Vanlandeghem, and the TTU Bass Club for helping collect Guadalupe bass. I thank the South Llano River landowners for their support and allowance of access during sample collections. I am also thankful to Dijar Lutz-Carrillo at the A.E. Wood State Fish Hatchery for teaching and assisting me in my genetic analysis. Lastly, I am grateful for the support from my family and friends. God has blessed me on this great journey, and your support, motivation, and advice has always helped. Funding was provided by a U.S. Fish and Wildlife Service State Wildlife Grant administered by Texas Parks and Wildlife Department (contract number 415385) and the U.S. Geological Survey (cooperative agreement number G11AC20436). ii Texas Tech University, Jillian Groeschel, December 2013 TABLE OF CONTENTS ACKNOWLEDGMENTS............................................................................................... ii ABSTRACT.................................................................................................................... iv LIST OF TABLES........................................................................................................... v LIST OF FIGURES......................................................................................................... vii I. INTRODUCTION........................................................................................................ 1 II. METHODS.................................................................................................................. 7 Study Area............................................................................................................ 7 Habitat mapping of the South Llano River, Texas............................................... 8 Guadalupe bass PIT-tag telemetry...................................................................... 9 Guadalupe bass age and growth......................................................................... 10 Guadalupe bass genetics...................................................................................... 12 Data Analysis....................................................................................................... 13 III. RESULTS.................................................................................................................. 21 Instream habitat types and composition of the South Llano River, Texas........... 21 Guadalupe bass PIT-tag telemetry...................................................................... 22 Guadalupe bass population demographics-age and growth............................... 22 Guadalupe bass genetics...................................................................................... 23 Relation between habitat and Guadalupe bass growth....................................... 24 Guadalupe bass age-specific habitat associations.............................................. 24 Influence of discharge rate and fragment on Guadalupe bass growth rates....... 27 IV. DISCUSSION........................................................................................................... 44 Habitat mapping of the South Llano River, Texas............................................... 44 Guadalupe bass PIT-tag telemetry...................................................................... 46 Guadalupe bass population demographics-age and growth............................... 48 Guadalupe bass genetics...................................................................................... 50 Relation between habitat and Guadalupe bass growth....................................... 50 Guadalupe bass age-specific habitat associations.............................................. 52 Influence of discharge rate and fragment on Guadalupe bass growth rates....... 54 Conclusions.......................................................................................................... 56 REFERENCES................................................................................................................ 58 iii Texas Tech University, Jillian Groeschel, December 2013 ABSTRACT Guadalupe bass Micropterus treculii is a black bass species endemic to central Texas. Its dependence on undisturbed pool and run habitats with sufficient flow and cover renders it sensitive to habitat alteration. The decline of the species due to habitat alteration/loss and introgressive hybridization with introduced smallmouth bass Micropterus dolomieu has prompted efforts to restore Guadalupe bass habitats. However, detailed data on how the species may respond to these efforts are lacking. I assessed age- specific Guadalupe bass habitat associations and habitat specific growth rates at three different scales (fine, intermediate, and coarse) in the South Llano River. Substrates were classified using side-scan sonar. Scales and otoliths were extracted from Guadalupe bass to determine age and growth. Over 65% of captured Guadalupe bass were age-2 or age-3, but individuals ranged from 0-7 years of age. Overlap in habitat associations was exhibited between age classes 1-3+. Age-0 Guadalupe bass tended to associate with greater proportions of pool and run mesohabitats with submerged aquatic substrates. Finally, low discharge rates appeared to have the greatest influence on Guadalupe bass growth rates with growth exhibiting a negative correlation with the proportion of discharge observations falling in the Q90 range in a given year. My results suggest age- specific Guadalupe bass habitat associations that may increase the effectiveness of restoration efforts directed at the species. Further application of these results may allow the use of the Guadalupe bass population trajectories and habitat occupation rates as an indicator of stream health in Edwards Plateau streams or as a predictor of changes in stream condition. iv Texas Tech University, Jillian Groeschel, December 2013 LIST OF TABLES 1. Classification of substrate type and instream cover (Cummins & Lauff 1969; Minshall 1984; Quinn & Hickey 1990, Snedden 1999, Perkin et al. 2010) used to classify substrates of the South Llano River, Texas based on side scan sonar imagery collected in October 2011.................. 16 2. List of six multiplex polymerase chain reactions (PCRs) used for Guadalupe bass fin clips captured from the South Llano River, Texas in spring 2012 – fall 2012....................................................................................... 17 3. Relocated and recaptured PIT-tagged Guadalupe bass and associated habitat type in the South Llano River, TX from May – August 2012, November 2012, and July........................................................................ 29 4. Mean (±SE) back-calculated total length (TL) at each annulus of Guadalupe bass captured in the South Llano River, Texas from April – November 2012........................................................................................ 30 5. Age-length key based on the total length (TL) at age and age at capture of Guadalupe bass captured in the South Llano River, Texas from April 2012 – November 2012. Numbers in rows give the probability (%) that a Guadalupe bass within the 20-mm length interval is a certain age............................................................................ 31 6. Discriminant analysis of hybrids versus