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Resource and Habitat Use of Northern Bottlenose Whales in the Gully: Ecology, Diving and Ranging Behaviour

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Resource and Habitat Use of Northern Bottlenose Whales in the Gully: Ecology, Diving and Ranging Behaviour Resource and habitat use of northern bottlenose whales in the Gully: ecology, diving and ranging behaviour by Sascha K. Hooker Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Dalhousie University Halifax, Nova Scotia Canada August 1999 © Copyright by Sascha K. Hooker, 1999 DALHOUSIE UNIVERSITY FACULTY OF GRADUATE STUDIES The undersigned hereby certify that they have read and recommend to the Faculty of Graduate Studies for acceptance a thesis entitled "Resource and habitat use of northern bottlenose whales in the Gully: ecology, diving and ranging behaviour" by Sascha Hooker in partial fulfillment of the requirements for the degree of Doctor of Philosophy Dated: August 3, 1999 External Examiner Robert D. Kenney Research Supervisor Hal Whitehead Examining Committee Sara Iverson Ron O'Dor Don Bowen ii DALHOUSIE UNIVERSITY 18 August 1999 AUTHOR: Sascha K. Hooker TITLE: Resource and habitat use of northern bottlenose whales in the Gully: ecology, diving and ranging behaviour DEPARTMENT: Biology DEGREE: Ph.D. CONVOCATION: October YEAR: 1999 Permission is herewith granted to Dalhousie University to circulate and to have copied for non-commercial purposes, at its discretion, the above title upon the request of individuals or institutions. Signature of Author The author reserves other publication rights, and neither the thesis nor extensive extracts from it may be printed or otherwise reproduced without the author's written permission. The author attests that permission has been obtained for the use of any copyrighted material appearing in this thesis (other than brief excerpts requiring only proper acknowledgement in scholarly writing), and that all such use is clearly acknowledged. iii TABLE OF CONTENTS LIST OF TABLES ............................................................................................................... vii LIST OF FIGURES............................................................................................................... ix ABSTRACT ........................................................................................................................ xii LIST OF ABBREVIATIONS AND SYMBOLS ................................................................... xiii ACKNOWLEDGEMENTS ................................................................................................. xiv PUBLICATIONS................................................................................................................ xvi CHAPTER ONE INTRODUCTION .................................................................................................................... 1 HABITAT AND RESOURCE USE..................................................................................1 THE NORTHERN BOTTLENOSE WHALE, HYPEROODON AMPULLATUS..................3 Phylogeny and systematics............................................................................................3 General characteristics ..................................................................................................5 The whaling industry ....................................................................................................5 Conservation status .......................................................................................................8 Distribution ..................................................................................................................8 Migration.....................................................................................................................9 Prey...........................................................................................................................13 Predators and parasites................................................................................................13 Population structure....................................................................................................13 Life history.................................................................................................................14 Genetics.....................................................................................................................15 THE GULLY ................................................................................................................15 THE INTER-RELATIONSHIP OF ECOLOGICAL PARAMETERS ...............................17 CHAPTER TWO DIET AND FORAGING ECOLOGY OF NORTHERN BOTTLENOSE WHALES IN THE GULLY: FATTY ACID AND STABLE ISOTOPE ANALYSES OF BIOPSY SAMPLES .................................. 20 ABSTRACT .................................................................................................................20 INTRODUCTION.........................................................................................................21 METHODS...................................................................................................................25 Sample collection .......................................................................................................25 Fatty acid analysis ......................................................................................................27 Stable isotope analysis ................................................................................................29 RESULTS.....................................................................................................................29 Bottlenose whale lipids and fatty acids .........................................................................29 Bottlenose whale stable isotopes..................................................................................33 Bottlenose whale male-female differences....................................................................34 Gonatus fatty acids and stable isotopes.........................................................................36 Comparison of fatty acids in Gonatus to those in bottlenose whale biopsies....................37 DISCUSSION ...............................................................................................................41 Viability of using blubber biopsies for inferring aspects of diet......................................41 Bottlenose whale blubber ............................................................................................41 Gonatus samples ........................................................................................................42 Dietary information from biopsy samples.....................................................................44 Conclusion .................................................................................................................49 iv CHAPTER THREE THE INFLUENCE OF BIOTIC AND ABIOTIC OCEANOGRAPHIC FEATURES ON THE DISTRIBUTION OF NORTHERN BOTTLENOSE WHALES IN A SUBMARINE CANYON ............... 51 ABSTRACT .................................................................................................................51 INTRODUCTION.........................................................................................................52 METHODS...................................................................................................................55 Fieldwork...................................................................................................................55 Analyses ....................................................................................................................57 RESULTS.....................................................................................................................59 Abundance.................................................................................................................61 Distribution ................................................................................................................61 Annual variation in weather conditions.........................................................................75 DISCUSSION ...............................................................................................................77 Conclusion .................................................................................................................81 CHAPTER FOUR DIVING AND RANGING BEHAVIOUR OF ODONTOCETES : A METHODOLOGICAL REVIEW AND CRITIQUE........................................................................................................................... 82 ABSTRACT .................................................................................................................82 INTRODUCTION.........................................................................................................83 DIVING METHODOLOGY ..........................................................................................86 Techniques.................................................................................................................89 Sampling regime.........................................................................................................90 Data retrieval..............................................................................................................92 RANGING STUDIES AND SPATIO-TEMPORAL SCALE............................................94 DEPLOYMENT AND ATTACHMENT TECHNIQUES.................................................97 SUMMARISING DIVING AND RANGING BETWEEN STUDIES ...............................98 Definition of diving behaviour .....................................................................................98
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