Exploring Mechanisms Underlying Recruitment of White Crappie in Ohio Reservoirs
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EXPLORING MECHANISMS UNDERLYING RECRUITMENT OF WHITE CRAPPIE IN OHIO RESERVOIRS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By David B. Bunnell, B.S., M.S. * * * * * The Ohio State University 2002 Dissertation Committee: Approved by Professor Roy A. Stein, Advisor Professor Joseph R. Holomuzki _________________________ Advisor Professor Elizabeth A. Marschall Department of Evolution, Ecology, and Organismal Biology Professor Allison A. Snow ABSTRACT Organisms that produce many, small offspring generally exhibit variable population size, owing to variation in production and survival of offspring. Using a life- history approach, we focused on ecological mechanisms underlying the production and survival of white crappie Pomoxis annularis, a popular North American sport fish exhibiting high variability in recruitment to maturity (i.e., age-2). Offspring production begins with adult energy allocation to reproduction. Female white crappies initiate ovary development during autumn, 6 months before spring spawning. To understand why females develop ovaries “early”, we used optimality and simulation models. Results revealed that early ovary development is an adaptation to uncertainty in spring feeding conditions. To investigate how mean condition and egg production of the adult population influence larval density and age-2 catch per effort (CPE), we sampled white crappie from 14 reservoirs. Although mean condition influenced ovary characteristics, only population egg production influenced larval density and age-2 CPE. Thus, population egg production can limit recruitment success. After larvae hatch, numerous mortality events occur before recruitment to age-2. We focused on two periods: between the larval and juvenile stage and during the first ii winter of life. In reservoirs, we evaluated how zooplankton density, water temperature, and larval density influenced larval growth and survival. Growth increased with zooplankton density, whereas survival was unrelated to any measured variable. We then evaluated how food, fish size, and winter severity influenced winter survival in the lab. Winter severity regulated survival with only 47% of the juveniles surviving the severe winter, and 97% surviving the mild winter. Although temperatures < 4ºC caused mortality in the lab, fish may occupy ≥ 4ºC habitat during Ohio winters in the field. Overall, white crappie recruitment is likely set by the egg or larval stage, though considerable winter mortality remains a possibility. With this caveat, we recommend that managers use catch restrictions to increase adult biomass and subsequent egg production to improve poor recruitment. Higher egg production should increase larval density and ultimately the number of fish recruiting to both maturity and the sport fishery. iii ACKNOWLEDGMENTS I am grateful for extraordinary help while completing my degree at Ohio State. First, I want to thank my advisor, Roy Stein. He has a unique combination of intelligence, organization, and vision, and I am grateful to him for providing me with an opportunity to grow as a scientist. I will always appreciate his steadfast support and friendship during my graduate tenure. Special gratitude also is due to Elizabeth Marschall, whose wisdom and advice I was very fortunate to receive over the years. I also want to thank Joe Holomuzki and Allison Snow for improving both the science and presentation of my research. At the Aquatic Ecology Lab, interactions with other graduate students have contributed largely to my intellectual growth. I want to thank Kristi Arend, Matt Fairchild, Grace Kilbane, Stuart Ludsin, Gene Kim, Felix Martinez, Stephanie Micucci, Jeff Spoelstra, Jon Sieber-Denlinger, LeAnn Southward, and Geoff Steinhart. I also was extremely fortunate to overlap briefly with the previous cohort of graduate students, including Mary Bremigan, Jim Garvey, and Mark Kershner. This research depended on a talented and dedicated technical staff that always helped me maintain a positive outlook over the years. Jen Pyzoha was the heart and soul of “Team Crappie” as we later came to be known, and deserves much of the credit for this research. Other full-time employees to whom I am grateful include Julie Fricke, Rick Ginsberg, Dave Gloeckner, Cliff Hutt, Adam Peer, Mike Schmidt, Amy Spencer, iv Sara Thomas, and Jeff Williams. In addition, valuable, part-time assistance was provided by Katie Bauman, Kelly Danczak, Rene Esteves, Aaron Gallagher, David Glover, Mike Haugen, Tony Iarussi, Eric Kohagen, Betsy Lutmerding, Heather McLean, Jim Ritchie, Matt Thomas, and Mark Tomasi. Undergraduates Matt Scantland and Artie McCollum invested considerable time and intellect in their honor’s thesis research projects, which made significant contributions to our understanding of white crappie recruitment. Finally, I would like to thank Melissa Marburger and Beth DeWitt for always providing excellent technical assistance to my research. All AEL students were fortunate to have the two of you on their side! I was extremely fortunate to be supported in numerous ways by the Ohio Department of Natural Resources. Although many individuals contributed countless hours in the field, biologists including Dave Bright, John Golz, Phil Hillman, Ed Lewis, Marty Lundquist, Joel Plott, and Deb Walters were most helpful in coordinating sampling events. I thank Randy Miller, Joe Mion, and Ray Petering for supporting this project, even in the early years when the sample processing dollars seemed unending. I want to especially thank Scott Hale, upon whose advice and insights I have relied upon since the inception of this project. His willingness to think outside the box will improve fisheries management for many years to come. Finally, Craig Billingsley and Freeman Johns, of the Pennsylvania Fish and Boat Commission always supported this research through their annual sampling of Pymatuning Reservoir. v Lastly, I want to thank my family for their continual love and support through the long graduate school years. And to my wife, friend, and colleague, Siri Ibargüen, your love and friendship have enriched my life- thank you. This work was supported by the Ohio Department of Natural Resources, Division of Wildlife, the Department of Evolution, Ecology, and Organismal Biology, and a University Fellowship awarded by The Ohio State University. vi VITA May 3, 1973 ...................................... Born – Lexington, Kentucky 1995 .................................................. B.S. Biology, Centre College, Danville, KY 1997 .................................................. M.S. Clemson University, Clemson, SC 1995 – 1997....................................... Graduate Research Associate Clemson University, Clemson, SC 1997 – 1998....................................... University Fellow The Ohio State University, Columbus, Ohio 1998 – present ................................... Graduate Teaching and Research Associate The Ohio State University, Columbus, Ohio PUBLICATIONS 1. Burrell, K. B., D. L. Van Lear, D. B. Bunnell, J. J. Isely, and C. A. Dolloff. 2000. Seasonal movement of brown trout in the Chattooga River watershed. Transactions of the American Fisheries Society 129:1373-1379. 2. Bunnell, D. B. and J. J. Isely. 1999. Influence of temperature on mortality and retention of simulated transmitters in rainbow trout. North American Journal of Fisheries Management 19:152-154. 3. Bunnell, D. B., J. J. Isely, K. B. Burrell, and D. L. Van Lear. 1998. Diel movement of brown trout in a southern appalachian river. Transactions of the American Fisheries Society 127: 630-636. FIELDS OF STUDY Major Field: Evolution, Ecology, and Organismal Biology vii TABLE OF CONTENTS Page Abstract.....................................................................................................................ii Acknowledgments .................................................................................................... iv Vita ......................................................................................................................... vii List of Tables............................................................................................................ xi List of Figures ........................................................................................................ xiv Chapters: 1. Introduction ...................................................................................................1 Overview of chapters..........................................................................5 Chapter 2................................................................................5 Chapter 3................................................................................6 Chapter 4................................................................................6 Chapter 5................................................................................7 Summary ................................................................................7 2. Optimal energy allocation: when should allocation to ovaries resume after spawning? ...................................................................................................10 Introduction......................................................................................10 Methods ...........................................................................................13 White crappie life history......................................................13