Incorporating Migration and Local Movement Patterns into Management Strategies for Spiny Dogfish (Squalus acanthias) by Jennifer Cudney Director of Dissertation: Roger A. Rulifson, Ph.D Major Department: Coastal Resources Management Ph.D Program December, 2015 ABSTRACT OF DISSERTATION The overall purpose of this dissertation is to increase understanding of migration and movement behaviors associated with a highly migratory elasmobranch species. In particular, I seek to determine whether sufficient evidence exists to warrant the separation of the northwest Atlantic Spiny Dogfish (Squalus acanthias) into separate management units. These management units are not genetically distinct, but rather would be based on unique behaviors adopted by hypothesized groups of dogfish that connect reproductive, feeding, and overwintering grounds (“contingents”). This dissertation includes an introductory chapter that introduces the reader to the Spiny Dogfish resource and recent management actions undertaken, followed by a chapter that provides technical and design recommendations based on a meta-analysis and a case study, which address the challenges of conducting behavioral research in dynamic environments through the use of acoustic telemtry. Approximately 30 percent of papers reviewed had no details on design specifications. Meta-analyses suggest that more fish were redetected when more acoustic equipment was deployed for longer periods of time, exemplifying the need for robust equipment that can withstand the rigors of an offshore, dynamic environment. In particular, we found that a heavy anchor, a subsurface float holding a mooring line, and a highflier-float system produced the best results in our case study. New behavioral information, derived from an analysis of data collected through a long-term conventional mark-recapture program and a multi-year acoustic tagging program, suggest that spiny dogfish tagged off North Carolina in overwintering grounds routinely make seasonal migrations to summer feeding habitats off southern New England (specifically, Massachusetts), but do not necessarily follow the same pathway each year. Sharks were often not detected on acoustic receivers for lengthy periods of time, and mark-recapture data indicated extremely lengthy times at liberty (1,000+ days). Spiny Dogfish were also noted to be locally abundant but exhibit short residency times on the Hatteras Bight acoustic array. An evaluation of potential environmental drivers of localized behavior in the southern extent of the Spiny Dogfish range noted that certain factors (i.e., water temperature and weather) had an effect on the presence and absence of dogfish in the Hatteras Bight. Finally, the dissertation discusses the Spiny Dogfish Contingent Hypothesis, which suggests that the northwestern Atlantic stock could comprise as many as five behaviorally distinct groups of Spiny Dogfish. The work presented in this dissertation identifies predictable behavioral patterns undertaken by individual Spiny Dogfish and inferred from recapture data, which can be used in context with future studies to further evaluate and refine the Spiny Dogfish Contingent Hypothesis. Despite many examples in the literature where Contingent Theory has been applied to describe spatially complex behavior in fish stocks, it is rarely applied in management plans. The current management structure in place for Spiny Dogfish is complex, has evolved to respond to fishery needs over the past 16 years, and involves multiple state and federal agencies, councils and commissions. Future research would likely need to quantify contingent “vital rates” and/or contribution to overall spawning stock biomass or fisheries to fully justify the development of a new management framework. Incorporating Migration and Local Movement Patterns into Management Strategies for Spiny Dogfish (Squalus acanthias) A Dissertation Presented To the Faculty of the Institute for Coastal Science and Policy East Carolina University In Partial Fulfillment of the Requirements for the Degree Doctorate of Philosophy in Coastal Resources Management Primary Concentration in Coastal and Estuarine Ecology Secondary Concentrations in Coastal Geosciences and Social Science & Coastal Policy by Jennifer L. Cudney December, 2015 © Jennifer Cudney 2015 Incorporating Migration and Local Movement Patterns into Management Strategies for Spiny Dogfish (Squalus acanthias) by Jennifer L. Cudney APPROVED BY: DIRECTOR OF DISSERTATION: _____________________________________________________ (Dr. Roger A. Rulifson, Ph.D COMMITTEE MEMBER: ______________________________________________ (Dr. Hans Vogelsong, Ph.D) COMMITTEE MEMBER: ______________________________________________ (Dr R. Wilson Laney, Ph.D) COMMITTEE MEMBER: ______________________________________________ (Dr Thomas Crawford, Ph.D) COMMITTEE MEMBER: ______________________________________________ (Dr. Ryan Mulligan, Ph.D) CHAIR OF THE DEPARTMENT OF COASTAL RESOURCES MANAGEMENT PH.D PROGRAM: _____________________________________ (Dr Siddhartha Mitra, Ph.D) DEAN OF THE GRADUATE SCHOOL: _______________________________________________ Paul J. Gemperline, PhD DEDICATION I dedicate this project, and all of the associated blood, sweat, tears, shark bites, sunburns, and sea-sickness, to my family and friends. And to my sister, because she asked me to do so. ACKNOWLEDGEMENTS Funding for this project was provided through North Carolina Sea Grant’s Fishery Resources Grant Program (08-FEG-11), the U.S. Fish and Wildlife Service, and East Carolina University. I would like to thank my advisor, Dr. Roger Rulifson, and my committee members (Dr. Tom Crawford, Dr. Ryan Mulligan, Dr. Hans Vogelsong, and Dr. R.Wilson Laney) for their guidance, assistance, and support through the development of this dissertation. This project could not have happened without fishermen Dewey Hemilright (Manteo, NC) and Chris Hickman (Hatteras, NC). I am forever grateful to them for welcoming me on their vessels and in their homes, and teaching me about their livelihoods. I am grateful to the faculty and staff in the ECU Institute for Coastal Science and Policy, the Coastal Resources Management Ph.D program, and the Departments of Biology, Geography, Geology and Physics; the ladies on the ECU IACUC that taught me all I needed to know about shark surgeries; and the staff in the Office of Diving and Water Safety, especially Captain Eric Diaddorio, for help with equipment preparation, field trials, and gear deployment. I am thankful for the assistance and friendship of so many of my fellow ECU students. I also thank my colleagues, peers, and supervisors in the federal government, and the National Sea Grant Office staff running the Knauss Fellowship, for giving me the opportunities that have changed my life. I am indebted to my family, friends, dance sisters and teachers, and especially my husband for their support, patience, and love these past eight years. TABLE OF CONTENTS CHAPTER 1: CHALLENGES OF MANAGING ELASMOBRANCH FISHERIES AT THE APPROPRIATE UNIT STOCK – THE CASE OF THE SPINY DOGFISH (SQUALUS ACANTHIAS) .... 1 Introduction ............................................................................................................................................... 1 Unique Challenges in Managing Elasmobranch Fisheries ........................................................................ 1 Elasmobranch Stock Identification. ...................................................................................................... 1 High Volume Elasmobranch Shark Fisheries. ...................................................................................... 4 Atlantic Spiny Dogfish Fisheries .............................................................................................................. 7 Spiny Dogfish Stock Assessments Imply A Stock Collapse and Rebuilding. ...................................... 9 Management Measures Adopted in Response to Spiny Dogfish Stock Assessment Results. ............ 13 Rapid Rebuilding of the Spiny Dogfish Stock. ................................................................................... 17 Research Objective ................................................................................................................................. 19 Dissertation Chapters .............................................................................................................................. 22 Preface/Introduction (Chapter 1): Challenges of Managing Elasmobranch Fisheries at the Appropriate Unit Stock - The Case of the Spiny Dogfish (Squalus acanthias). ................................. 22 Chapter 2: Design Considerations for Offshore Acoustic Arrays to Support Behavioral Research. .. 23 Chapter 3: Migration and Local Movement Patterns of Spiny Dogfish Overwintering in the Southern Mid-Atlantic Bight and off Cape Hatteras, North Carolina. ............................................................... 23 Chapter 4: Influence of Environmental Conditions on Overwintering Spiny Dogfish in the Hatteras Bight, North Carolina. ......................................................................................................................... 24 Chapter 5: The Spiny Dogfish Contingent Hypothesis – Proposed Delineation of Mid-Atlantic and Gulf of Maine Migratory Contingents. ............................................................................................... 25 Literature Cited ......................................................................................................................................