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Age and Growth Estimates for the Port Jackson Shark, Heterodontus Portusjacksoni, (Mayer, 1793) from New South Wales, Australia

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Age and Growth Estimates for the Port Jackson Shark, Heterodontus Portusjacksoni, (Mayer, 1793) from New South Wales, Australia AGE AND GROWTH ESTIMATES FOR THE PORT JACKSON SHARK, HETERODONTUS PORTUSJACKSONI, (MAYER, 1793) FROM NEW SOUTH WALES, AUSTRALIA. By ROBERT ØSTLIE RAMOS Cand. mag. Presented for the degree of Doctor of Philosophy School of Environmental and Life Sciences The University of Newcastle Australia May 2007 Declaration of Authorship I hereby certify that the work embodied in this thesis is the result of original research and has not been submitted for a higher degree to any other University or Institution. ----------------------------------- ROBERT ØSTLIE RAMOS 31 May 2007 Cover image: The Port Jackson shark, Heterodontus portusjacksoni, (photo by the author). 2 Acknowledgments It is not an easy task to start acknowledging all the people for their contributions to this thesis. However, if I have to start somewhere and with someone it has to be my supervisor Dr. William Gladstone. I am forever grateful for giving me the great opportunity to fulfil my dreams to pursue this degree and for all the help, advice, encouragement and trust from the beginning. I would not have finished this degree if it was not your support and it has been a great experience working with you. I am also very thankful for all the help and support given by all the staff members and especially Benjamin Brewer and Robert Townsend at Oceanworld Manly Aquarium. You all dedicated your time to helping maintain and respond to all of the different challenges that came by housing my Port Jackson sharks in your facility. I also have to thank Captain Brett Bollinger and his crew on the commercial fishing vessel Avalon Star for many intriguing discussions and giving me the opportunity to observe and collect all the sharks over these years. We all know that without your help and support there would not have been anything to write. A special thanks goes to my fellow researchers Steven Lindfield, Shanti Mors, Jason Morton, David Powter and Mohammad Reza Shokri, and for all their help in the ageing experiment and throughout my time here in Australia. Your friendship and knowledge will for ever be remembered. And I really hope we can meet up again in the future. 3 A special thanks also goes to all my friend back home in Oslo, Norway. Although we have not seen each other for a long time your friendship and encouragement for fulfilling this degree and believing in me has given me the will to finish. Last but not least, I have to thank my family above all, for their huge support and believe in me. Without you I would not have made it this far and finished this Ph.D. Thank you so much for all your help and for being there for me to fulfil my greatest dream and this big achievement. All procedures in this thesis involving the sharks were done under permits from NSW Fisheries, the University of Newcastle’s Animal Care and Ethics Committee, and Oceanworld Manly Aquarium Animal Care and Ethics. I thank you for your support and approval. 4 Table of Contents Declaration of Authorship................................................................................................... 2 Acknowledgments ................................................................................................................ 3 Table of Contents ................................................................................................................. 5 Abstract............................................................................................................................... 13 Chapter 1: General Introduction...................................................................................... 18 1.1 Problem Statement ............................................................................................. 18 1.2 Introduction to the Literature Review.............................................................. 21 1.3 Status and Threats.............................................................................................. 22 1.4 Ageing Techniques.............................................................................................. 26 1.5 Validation ............................................................................................................ 29 1.6 Growth Models ................................................................................................... 34 1.7 Application of Techniques ................................................................................. 37 1.8 Port Jackson Shark ............................................................................................ 38 1.9 Conclusion ........................................................................................................... 40 Chapter 2: Anatomy of the Vertebrae and Dorsal Spine of the Port Jackson Shark (Heterodontus portusjacksoni). .......................................................................................... 43 2.1 Introduction ........................................................................................................ 43 2.2 Materials and Methods....................................................................................... 46 2.2.1 Sampling ...................................................................................................... 46 2.2.2 Preparation of Vertebral Centra............................................................... 47 5 2.2.3 Preparation of Dorsal Spines ..................................................................... 49 2.3 Results.................................................................................................................. 49 2.3.1 Vertebral Centra......................................................................................... 50 2.3.1.1 Number of Vertebrae..................................................................... 50 2.3.1.2 Gross Anatomy............................................................................... 51 2.3.1.3 Relationship to Size........................................................................ 60 2.3.2 Dorsal Spines ............................................................................................... 62 2.3.2.1 Length and Width .......................................................................... 62 2.3.2.2 Gross Anatomy............................................................................... 63 2.3.2.3 Relationship to Size........................................................................ 68 2.4 Discussion ............................................................................................................ 73 2.4.1 Vertebral Centra......................................................................................... 73 2.4.2 Dorsal Spines ............................................................................................... 75 2.5 Conclusion ........................................................................................................... 76 Chapter 3: The Use of Vertebrae for Age Estimating the Port Jackson Shark (Heterodontus portusjacksoni). .......................................................................................... 78 3.1 Introduction ........................................................................................................ 78 3.2 Materials and Methods....................................................................................... 81 3.2.1 Sampling ...................................................................................................... 81 3.2.2 Preparation of Vertebrae ........................................................................... 83 6 3.2.3 Validation..................................................................................................... 85 3.2.3.1 Sampling ......................................................................................... 85 3.2.3.2 Maintenance ................................................................................... 85 3.2.3.3 Chemical Markers.......................................................................... 87 3.2.3.4 Marginal Increment Analysis and Centrum Edge Analysis ...... 89 3.2.4 Ageing........................................................................................................... 91 3.2.4.1 Techniques and Methods............................................................... 92 3.2.4.2 Whole Vertebrae ............................................................................ 93 3.2.4.3 Sectioned Vertebrae....................................................................... 93 3.2.5 Analyses ....................................................................................................... 94 3.2.5.1 Influence of Vertebra Number on Age Estimation..................... 94 3.2.5.2 Comparison of Whole and Sectioned Vertebral Centra............. 94 3.3 Results.................................................................................................................. 96 3.3.1 Relationship Between Length and Vertebral Diameter .......................... 96 3.3.2 Validation..................................................................................................... 96 3.3.3 Whole Vertebrae ....................................................................................... 100 3.3.3.1 Female ........................................................................................... 101 3.3.3.2 Male ............................................................................................... 103 3.3.4 Sectioned Vertebrae.................................................................................. 104 7 3.3.4.1
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