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Biology, Fisheries and Status of Longtail Tuna (Thunnus Tonggol), with Special Reference to Recreational Fisheries in Australian Waters

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Biology, Fisheries and Status of Longtail Tuna (Thunnus Tonggol), with Special Reference to Recreational Fisheries in Australian Waters Biology, fisheries and status of longtail tuna (Thunnus tonggol), with special reference to recreational fisheries in Australian waters FRDC Project 2008/058 Final Report 30 July 2010 • Shane Griffiths • Julian Pepperell • Mark Tonks • William Sawynok • Len Olyott • Sharon Tickell • Mitchell Zischke • John Burgess • Evan Jones • Doug Joyner • Judy Lynne • Chris Makepeace • Kane Moyle Biology, fisheries and status of longtail tuna (Thunnus tonggol), with special reference to recreational fisheries in Australian waters Shane Griffiths, Julian Pepperell, Mark Tonks, William Sawynok, Len Olyott, Sharon Tickell, Mitchell Zischke, Judy Lynne, John Burgess, Evan Jones, Doug Joyner, Chris Makepeace, Kane Moyle 30 July 2010 Fisheries Research and Development Corporation Project Number 2008/058 Final Report j0. i Copyright and disclaimer © Fisheries Research and Development Corporation and CSIRO Marine and Atmospheric Research 2010 This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Information may not be stored electronically in any form whatsoever without such permission. The authors do not warrant that the information in this document is free from errors or omissions. The authors do not accept any form of liability, be it contractual, tortious, or otherwise, for the contents of this document or for any consequences arising from its use or any reliance placed upon it. The information, opinions and advice contained in this document may not relate, or be relevant, to a reader’s particular circumstances. Opinions expressed by the authors are the individual opinions expressed by those persons and are not necessarily those of the publisher, research provider or the FRDC. The Fisheries Research and Development Corporation plans, invests in and manages fisheries research and development throughout Australia. It is a statutory authority within the portfolio of the federal Minister for Agriculture, Fisheries and Forestry, jointly funded by the Australian Government and the fishing industry. Title: Biology, fisheries and status of longtail tuna (Thunnus tonggol), with special reference to recreational fisheries in Australian waters ISBN: 9781921605741 (pbk.) Subjects: Tuna fishing—Australia, Fisheries—Australia, Fishery management—Australia. Author: Griffiths, Shane. P., 1975– Other Authors/Contributors: Julian Pepperell, Mark Tonks, William Sawynok, Len Olyott, Sharon Tickell, Mitchell Zischke, Judy Lynne, John Burgess, Evan Jones, Doug Joyner, Chris Makepeace and Kane Moyle Dewey Number: 639.27783 Cover designed by Shane Griffiths, CSIRO Marine and Atmospheric Research, cover photography by Dan Bergamo, Kurt Edwards and Mark Bargenquast. Published by CSIRO Marine and Atmospheric Research Enquiries should be addressed to: Dr Shane Griffiths Ph: 07 3826 7364 or e-mail: [email protected] [Cite as: Griffiths, S., Pepperell, J., Tonks, M., Sawynok, W., Olyott, L., Tickell, S., Zischke, M., Lynne, J., Burgess, J., Jones, E., Joyner, D., Makepeace, C., and Moyle, K. (2010) Biology, fisheries and status of longtail tuna (Thunnus tonggol), with special reference to recreational fisheries in Australian waters. FRDC Final Report 2008/058. 101 pp.] FRDC 2008/058 Final Report ii TABLE OF CONTENTS LIST OF FIGURES ................................................................................................... IV LIST OF TABLES................................................................................................... VIII 1. NON-TECHNICAL SUMMARY ...........................................................................9 2. ACKNOWLEDGEMENTS .................................................................................14 3. BACKGROUND ................................................................................................15 4. NEED.................................................................................................................16 5. OBJECTIVES ....................................................................................................16 6. LITERATURE REVIEW.....................................................................................17 6.1 Distribution................................................................................................17 6.2 Stock structure .........................................................................................18 6.3 Reproduction ............................................................................................18 6.4 Age, growth and longevity.......................................................................21 6.5 Feeding ecology .......................................................................................24 6.6 Movement ..................................................................................................25 6.7 Fisheries ....................................................................................................28 6.7.1 Commercial fisheries............................................................28 6.7.2 Recreational fisheries...........................................................31 7. NATIONAL LONGTAIL TUNA RECREATIONAL CATCH SURVEY ...............32 7.1 Introduction...............................................................................................32 7.2 Methods .....................................................................................................33 7.2.1 Online diary ...........................................................................33 7.2.2 Time-location sampling ........................................................37 7.2.3 Access point survey .............................................................38 7.2.4 Estimating survey costs.......................................................40 7.3 Results.......................................................................................................41 7.3.1 Innovative survey methods..................................................41 7.3.2 Fisher profiles .......................................................................44 7.3.3 Fishing methods ...................................................................45 7.3.4 Effort, catch and size distribution .......................................47 7.3.5 Access point survey .............................................................53 7.3.6 Comparison of survey costs and efficacy ..........................54 7.4 Discussion.................................................................................................57 8. PRELIMINARY STOCK ASSESSMENT...........................................................62 8.1 Background...............................................................................................62 FRDC 2008/058 Final Report iii 8.2 Objectives ................................................................................................. 63 8.3 Methodology............................................................................................. 63 8.3.1 Defining the stock ................................................................ 63 8.3.2 Fishery data used to estimate fishing mortality ................ 64 8.3.3 Estimates of mortality.......................................................... 65 8.3.4 Per-recruit analyses ............................................................. 67 8.4 Results ...................................................................................................... 70 8.4.1 Age structure exploited by fisheries .................................. 70 8.4.2 Age and size selectivity of fisheries ................................... 70 8.4.3 Mortality estimates ............................................................... 70 8.4.4 Per-recruit analyses ............................................................. 73 8.5 Discussion ................................................................................................ 76 9. BENEFITS AND ADOPTION............................................................................ 80 10. FURTHER DEVELOPMENT............................................................................. 81 11. CONCLUSION .................................................................................................. 82 12. REFERENCES.................................................................................................. 86 13. APPENDICES................................................................................................... 92 13.1 Appendix 1 ............................................................................................. 92 Intellectual property.......................................................................... 92 13.2 Appendix 2 ............................................................................................. 92 Project staff ....................................................................................... 92 Website development and graphic design ..................................... 92 Time-location sampling .................................................................... 92 13.3 Appendix 3 ............................................................................................. 93 Peer-reviewed publications arising from the project..................... 93 Newspaper and magazine publications .......................................... 93 Website publications .......................................................................
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