CHONDRICHTHYAN BYCATCH: RISK ASSESSMENT, SPATIOTEMPORAL TRENDS AND CONTRIBUTIONS TO MANAGEMENT MARCELO REIS A thesis submitted in fulfilment for the requirements for the degree of Doctor in Philosophy at the University of Sydney School of Life and Environmental Sciences Coastal and Marine Ecosystems Group Sydney, Australia August 2018 Attribution of authorship for published and collaborative work contained in this thesis The work contained in the body of this thesis, except otherwise acknowledged, is the result of my own investigations. For the four data chapters, I led and undertook the following: study design, field organization, data analysis, and writing of thesis chapters. - Chapter 2 and Chapter 3: I wrote these studies entirely and conducted the analyses based on the database built upon individual fishing logbooks provided by the Australian Fisheries Management Authority – AFMA. The study was designed by me in collaboration with the Co- Author Dr. Will Figueira. - Chapter 4 and Chapter 5: Sample collection was made by the Department of Primary Industries, New South Wales – DPI Fisheries Observer Program under the Animal Research Authority permission ACEC Ref 16/02 provided by the Primary Industries (Fisheries) Animal Care & Ethics Committee. The study was designed by me in collaboration with the Co-Author Dr. Will Figueira. Samples processing and collection of data as well data analyses writing of the study were conducted by me. Marcelo Reis Signature: Date: 23/08/2018 Table of Contents List of Tables .......................................................................................................................................... i List of Figures ...................................................................................................................................... iii Epigraph ............................................................................................................................................... vi Acknowledgements ............................................................................................................................. ix Thesis abstract ..................................................................................................................................... 1 Chapter 1 – General Introduction: Australian chondrichthyans: Diversity, Status, Fisheries and Threats ........................................................................................................................................... 3 IUCN Status of Australian Chondrichthyans ............................................................................ 4 The bycatch threat ....................................................................................................................... 6 Chondrichthyan fisheries in Australia ........................................................................................ 7 Conservation and Management ................................................................................................. 9 Research objectives of this work ............................................................................................. 10 REFERENCES ............................................................................................................................... 13 Chapter 2 – Assessing the relative vulnerability of Chondrichthyes species as bycatch using spatially reported catch data series ................................................................................................. 15 ABSTRACT ..................................................................................................................................... 15 INTRODUCTION ............................................................................................................................ 16 METHODS....................................................................................................................................... 18 The Southern and Eastern Scalefish and Shark Fishery ..................................................... 18 Species Occurrence Database ................................................................................................ 20 Fishery Interaction Index ........................................................................................................... 21 Species resilience ...................................................................................................................... 23 Assessing vulnerability .............................................................................................................. 23 RESULTS ........................................................................................................................................ 26 Catch events ............................................................................................................................... 26 Fishery interaction index ........................................................................................................... 27 Catch-MSY results ..................................................................................................................... 27 Resilience parameters ............................................................................................................... 27 Fishery interaction index and resilience parameters ............................................................ 28 Overall Priorities ......................................................................................................................... 32 DISCUSSION .................................................................................................................................. 35 REFERENCES ............................................................................................................................... 39 iii Chapter 3 – Spatial and temporal trends in bycatch diversity of chondrichthyans in Australia fisheries ................................................................................................................................................ 41 ABSTRACT ..................................................................................................................................... 41 INTRODUCTION ............................................................................................................................ 42 METHODS....................................................................................................................................... 44 Data source ................................................................................................................................. 44 Data analysis ............................................................................................................................... 45 RESULTS ........................................................................................................................................ 49 Frequency of Bycatch ................................................................................................................ 49 Chondrichthyan bycatch ratios ................................................................................................. 49 Chondrichthyan bycatch per unit of effort ............................................................................... 56 Chondrichthyan bycatch diversity ............................................................................................ 64 DISCUSSION .................................................................................................................................. 70 REFERENCES ............................................................................................................................... 75 Chapter 4 – Age, growth and reproductive biology of two endemic demersal bycatch chondrichthyans: Trygonorrhina fasciata & Dipturus australis from Eastern Australia ........... 78 ABSTRACT ..................................................................................................................................... 78 INTRODUCTION ............................................................................................................................ 79 METHODS....................................................................................................................................... 82 Sample source ............................................................................................................................ 82 Body metrics and condition ....................................................................................................... 83 Age and growth ........................................................................................................................... 84 Reproductive capacity ............................................................................................................... 86 RESULTS ........................................................................................................................................ 87 Length and Length-Weight Relationships .............................................................................. 87 Age and Growth .......................................................................................................................... 88 Body condition and reproductive data ..................................................................................... 92 DISCUSSION .................................................................................................................................