FINAL REPORT Determining Blue-eye Trevalla stock structure and improving methods for stock assessment Alan Williams, Paul Hamer, Malcolm Haddon, Simon Robertson, Franziska Althaus, Mark Green, Johnathan Kool January 2017 FRDC Project No 2013/015 © 2017 Fisheries Research and Development Corporation. All rights reserved. ISBN 978-1-4863-0756-2 FRDC report: Determining Blue-eye Trevalla stock structure and improving methods for stock assessment, Hobart, May, 2017. FRDC Project No 2013/015. 123p. Williams, A. Hamer, P, Haddon, M, Robertson, S, Althaus, F, Green, M. and Kool, J. (2016). - Online Determining Blue-eye Trevalla stock structure and improving methods for stock assessment FRDC Project No 2013/015 2017 Ownership of Intellectual property rights Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this publication is owned by the Fisheries Research and Development Corporation and CSIRO Oceans & Atmosphere This publication (and any information sourced from it) should be attributed to Williams, A. Hamer, P, Haddon, M, Robertson, S, Althaus, F, Green, M. and Kool, J. (2016). Determining Blue-eye Trevalla stock structure and improving methods for stock assessment, Hobart, December, 2017. 124p. Creative Commons licence All material in this publication is licensed under a Creative Commons Attribution 3.0 Australia Licence, save for content supplied by third parties, logos and the Commonwealth Coat of Arms. 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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. Researcher Contact Details FRDC Contact Details Name: Alan Williams Address: 25 Geils Court Address: Castray Esplanade Deakin ACT 2600 Hobart TAS 7001 Phone: 02 6285 0400 Phone: 03 6232 5222 Fax: 02 6285 0499 Fax: Email: [email protected] Email: [email protected] Web: www.frdc.com.au In submitting this report, the researcher has agreed to FRDC publishing this material in its edited form. ii Contents Acknowledgments ................................................................................................................................ xii Executive Summary ........................................................................................................................... xiii Introduction ........................................................................................................................................... 1 Objectives ............................................................................................................................................... 3 Method .................................................................................................................................................... 4 Rationale ......................................................................................................................................4 Data sources ................................................................................................................................4 Results and Discussion .......................................................................................................................... 6 1. Data collation and biology ........................................................................................................6 Catch distribution ........................................................................................................................6 Length frequency distribution ...................................................................................................13 Biology and ecology ..................................................................................................................18 2. Otolith ageing .........................................................................................................................23 Daily and annual ageing methods for otoliths of the Blue-eye Trevalla (Hyperoglyphe antarctica) .................................................................................................................................23 Introduction ...............................................................................................................................23 Method ......................................................................................................................................23 Results .......................................................................................................................................29 Discussion .................................................................................................................................36 3. Spatial analysis of age and growth ...............................................................................................38 Spatial variation in age and growth in Blue-eye Trevalla (Hyperoglyphe antarctica) supports the concept of separate populations on seamounts and the continental slope .............38 Introduction ...............................................................................................................................38 Methods .....................................................................................................................................39 Results .......................................................................................................................................45 Discussion .................................................................................................................................58 4. Otolith chemistry .........................................................................................................................60 Application of otolith chemistry life history profiles and stable isotope analysis to resolve population structure of Blue-eye Trevalla (Hyperoglyphe antarctica) .....................................60 Introduction ...............................................................................................................................60 Methodology .............................................................................................................................62 Results .......................................................................................................................................67 Discussion .................................................................................................................................85 5. Ecological dispersal modelling ....................................................................................................89 Quantifying the potential connectivity of Blue-eye Trevalla between spawning areas and fishing grounds to infer species sub-structure (stock structure) across its Australian range .....89 Introduction ...............................................................................................................................89 Materials and Methods ..............................................................................................................90 Results .......................................................................................................................................94 Discussion .................................................................................................................................99 Conclusion .......................................................................................................................................... 102 Stock structure .........................................................................................................................102 Management implications .......................................................................................................104 Implications ........................................................................................................................................ 105 iii Recommendations ............................................................................................................................. 105 Extension and Adoption .................................................................................................................... 106 Project coverage .............................................................................................................................106