SPATIAL MANAGEMENT OF SOUTHERN GARFISH (HYPORHAMPHUS MELANOCHIR) IN SOUTH AUSTRALIA – STOCK STRUCTURE AND ADULT MOVEMENT MA Steer, AJ Fowler, and BM Gillanders (Editors). Final Report for the Fisheries Research and Development Corporation FRDC Project No. 2007/029 SARDI Aquatic Sciences Publication No. F2009/000018-1 SARDI Research Report Series No. 333 ISBN 9781921563089 October 2009 i Title: Spatial management of southern garfish (Hyporhamphus melanochir) in South Australia – stock structure and adult movement Editors: MA Steer, AJ Fowler, and BM Gillanders. South Australian Research and Development Institute SARDI Aquatic Sciences 2 Hamra Avenue West Beach SA 5024 Telephone: (08) 8207 5400 Facsimile: (08) 8207 5406 http://www.sardi.sa.gov.au DISCLAIMER 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 readers 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. © 2009 Fisheries Research and Development Corporation and SARDI Aquatic Sciences. This work is copyright. Apart from any use as permitted under the Copyright Act 1968 (Cwth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Neither may information be stored electronically in any form whatsoever without such permission. 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. Printed in Adelaide: October 2009 Reviewers: Dr Craig Noell, Dr Milena Fernandes and an anonymous external referee Approved by: Dr Tim Ward, Principal Scientist: Wild Fisheries, SARDI Aquatic Sciences Signed: Date: 12 October 2009 Circulation: Public Domain ii TABLE OF CONTENTS TABLE OF CONTENTS .................................................................................................................... III LIST OF FIGURES ............................................................................................................................... V LIST OF TABLES .............................................................................................................................. VII NON-TECHNICAL SUMMARY: ..................................................................................................... IX LIST OF ACRONYMS ...................................................................................................................... XII 1 GENERAL INTRODUCTION .................................................................................................... 1 1.1 OVERVIEW ............................................................................................................................. 1 1.2 BACKGROUND ........................................................................................................................ 1 1.2.1 South Australia’s garfish fishery ...................................................................................... 1 1.2.2 Stock discrimination ......................................................................................................... 3 1.2.3 South Australia’s physico-chemical oceanography .......................................................... 4 1.3 NEED ...................................................................................................................................... 6 1.4 OBJECTIVES ........................................................................................................................... 7 1.5 REFERENCES .......................................................................................................................... 7 2 AGE-RELATED MOVEMENT PATTERNS AND POPULATION STRUCTURING IN SOUTHERN GARFISH (HYPORHAMPHUS MELANOCHIR) INFERRED FROM OTOLITH CHEMISTRY. ...................................................................................................................................... 11 2.1 INTRODUCTION..................................................................................................................... 11 2.2 MATERIALS AND METHODS ................................................................................................. 12 2.2.1 Sample collection ............................................................................................................ 12 2.2.2 Otolith preparation ......................................................................................................... 12 2.2.3 Trace element analysis ................................................................................................... 13 2.2.4 Relating trace element profile to fish age ....................................................................... 14 2.2.5 Data analyses ................................................................................................................. 15 2.3 RESULTS .............................................................................................................................. 17 2.3.1 Single element analyses .................................................................................................. 17 2.3.2 Multi-element analyses ................................................................................................... 19 2.3.3 Fine-scale spatial discrimination ................................................................................... 19 2.3.4 Broad-scale regional discriminations ............................................................................ 23 2.4 DISCUSSION ......................................................................................................................... 25 2.5 REFERENCES ........................................................................................................................ 29 3 STOCK DISCRIMINATION OF SOUTHERN GARFISH (HYPORHAMPHUS MELANOCHIR) BY STABLE ISOTOPE RATIO ANALYSIS OF OTOLITH CARBONATE. 33 3.1 INTRODUCTION..................................................................................................................... 33 3.2 MATERIALS AND METHODS ................................................................................................. 34 3.2.1 Sample collection ............................................................................................................ 34 3.2.2 Stable isotope analysis .................................................................................................... 35 3.2.3 Data analyses ................................................................................................................. 36 18 3.2.4 Calculation of expected δ O values ............................................................................... 37 3.3 RESULTS .............................................................................................................................. 38 18 3.3.1 Variation in δ O ............................................................................................................ 38 13 3.3.2 Variation in δ C ............................................................................................................ 40 3.3.3 Fine-scale spatial discrimination ................................................................................... 41 3.3.4 Broad-scale regional discrimination .............................................................................. 44 3.4 DISCUSSION ......................................................................................................................... 46 3.5 REFERENCES ........................................................................................................................ 49 4 GEOGRAPHIC VARIATION OF SOUTHERN GARFISH HYPORHAMPHUS MELANOCHIR IN SOUTH AUSTRALIAN WATERS BASED ON OTOLITH MORPHOMETRICS AND SHAPE ANALYSIS. ............................................................................. 53 4.1 INTRODUCTION..................................................................................................................... 53 4.2 MATERIALS AND METHODS ................................................................................................. 54 iii 4.2.1 Sample collection ............................................................................................................ 54 4.2.2 Image and shape analysis ............................................................................................... 54 4.2.3 Data analyses ................................................................................................................. 56 4.3 RESULTS .............................................................................................................................. 57 4.3.1 Spatial variation in otolith shape.................................................................................... 57 4.3.2 Fine-scale spatial discrimination ..................................................................................