Department of Sustainability and Environment Documenting the distribution, biology and ecology of Victoria's only threatened estuarine fish species Arthur Rylah Institute for Environmental Research Technical series No. 2008/89 Documenting the distribution, biology and ecology of Victoria's only threatened estuarine fish species TARMO A. RAADIK JEREMY 5. HINDELL Arthur Rylah Institute for Environmental Research 123 Brown Street, Heidelberg, Victoria 3084 November 2008 In partnership with: rv1elbourne Water Arthur Rylah Institute for Environmental Research Department of Sustainability and Environment Heidelberg, Victoria ill Report produced by: Arthur Rylah lnscirute for Environmental Research Depamm:m of Sustainability and Environment PO Box 137 Heidelberg, Victoria 3084 Phone (03) 9450 8600 Website: www.dse.vic.gov.au/ari ©Slate of Victoria, Department of Sustainability and Environment 2008 This publication is copyright. Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act 1968, no part may be reproduced, copied, transmitted in any form or by any means (electronic, mechanical or graphic) without the p1ior written permission of the St.ate of Victoria, Department of Su~tainability and Environment. All requests and enquires should be directed to the Customer Service Centre, 136 186 or email [email protected] Citation: Raadik, Tarn10 A. and Hindell, Jeremy S. (2008) Documenting the distribulion, biology and ecology of Victoria's only threatened esruarine fish species: the Pale Mangrove Goby (Mugilogobius placynotus Gunther, 1861). Arthur Rylah Institute for Environmental Research Technical Report Series No. 2008189. Department of Sustainability and Environment, Heidelberg, Victoria ISSN 1835-3827 (print) ISSN 1835-3835 (Online) Disclaimer: This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is wi thout flaw of any kind or is wholly appropriate for your panicular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Front cover photo: Mugilogobi•LS platynows (Tanno A. Raadik). Authorised by: Victorian Government, Melbourne Printed by: PRINTROOM. Preston, Melbourne iv v Contents LIST OF TABLES AND FIGURES ..................................................................................... vm ACKNOWLEDGEMENTS ....................................................................................................X S UMMARY ....................................................................................................................... l L"\JTRODUCTION ....................................................................................................... 2 1.1 P ROJECf OBJECTIVES ...................................................................................... 3 2 R EVIEW OF BIOLOGY/ECOLOGY/TAXONOMY ........................................................... 5 2.1 NAME .............................................................................................................. 5 2.2 OTHER COMMON NAMES ................................................................................ 5 2.3 OTHER SCIENTIFICNAMES .............................................................................. 5 2.4 D ISTINGUISHING FEATURES ............................................................................ 5 2.5 COLOUR .......................................................................................................... 5 2.6 SEXUAL DIMORPHlSM ................................ .......... ·········· ................................. 6 2.7 SIZE ................................................................................................................ 6 2.8 SIMil..AR SPECIES ............................................................................................ 6 2.9 D ISTRIBUTION ................................................................................................. 6 2.10 NATURALHISTORY .................................................. .... ................................... 6 2.10.1 Habitat .................................................................................................... 6 2.10.2 Physico-chemical Tolerances ................................................................. 7 2.10.3 Diet. ........................................................................................................ 7 2.10.4 Behaviour ........................................................ ....................................... 7 2.10.5 Age and Growth .............................................. ....................................... 7 2.10.6 Reproduction .......................................................................................... 7 2.10.7 Migration/movements ............................................................................ 8 2.10.8 Parasites and Diseases ............................................................................ 8 2. 11 TRANSLOCA TIONS ........................................................................................... 8 2.12 CONSERVATION STATUS ................................................................................. 8 2.13 TAXONOMY/GENETICS . ................................................................................... 8 2.14 U SAGE .......................................................................... .. ................................ 8 3 REVIEW OF PREVIOUS SAMPLING METHODS ............................................................ 9 4 REVJEW OF THE DISTRIBUTION OF MUGIWGOBJUS PLATYNOTUS IN WESTERN PORT AND PORT P HILLIP BA y ................................................................................................ 11 4.1 D ISTRIBUTION OF KEY HABITAT (A VICENNIA MARINA) ................................... 11 4.2 D OCUMENTED DISTRIBUTION OF MUGIWGOBIUS PLATYNOTUS lN W ESTERN P ORT AND PORT PHILLIP BAY ................................................................................... 17 vi 4.3 PREDICTED DISTRIBUTION OF MUGILOGOBJUS PLATYNOTUS JN W ESTERN PORT AND PORT PHILLIP B Ay ...................................................................... ············ .......... 18 5 REVIEW OF SMALL AND JUVENILE FISH ASSOCIATED WITH MANGROVES ............... 20 5. 1 VALUE OF MANGROVES TO FISH .................................................................... 20 5.2 A V ICTORIAN PERSPECTNE .......................................................................... 20 5.2.1 Bay-wide assessment of fish use of mangroves and mudflats ............. 21 5.2.2 Zonation of fish assemblages within mangroves ................................. 2 1 6 SURVEY OF CURRENT DISTRIBUTION AND BIOLOGY OF M UGILOGOBJUS Pl.ATYNOTUS 26 6.1 INTRODUCTION ............................................................................................. 26 6.2 MATERIALS AND METHODS ........................................................................... 26 6.2.1 Survey .................................................................................................. 26 6.2.2 Size and age structure of Mugilogobius plalynotus ............................. 27 6.2.3 Sex structure and fecundity .................................................................. 27 6.3 REsULTS AND DISCUSSION ............................................................................ 29 6.3.l Distribution of Mugilogobius platynotus ............................................. 29 6.3.2 Biology of Mugilogobius platynotus .......... ......................................... 32 6.3.3 Morphology of Mugilogobius platynotus ............................................ 32 6.3.4 Fish assemblages .................................................................................. 35 7 CONCLUSIONS AND R ECOivlMENDATIONS .............................................................. 38 8 REFERENCES ......................................................................................................... 39 vii List of tables and figures List of tabJes Table 1. Project tasks to review, describe and update the distribution, biology and ecology of the Pale Mangrove Goby in Port Phillip Bay and Western Port.............................................. 4 Table 2. Number of each species collected in each combination of time of year (summer, autumn, winter and spring) and habitat (mangrove - M, mudflat - UV) across Western Port and Corner Inlet. Data were pooled across bays, sites and sampling gears. From Hindell and Jenkins 2004 ....................................................................................................... 23 2 Table 3. Summary of mean abundances (µN - fish m' ) and lengths (µL- mm), total number 2 of samples, mean water depth, total number of species, abundance (fish m· ) and 2 biomass (g m" ) of fishes among habitats (forest, edge, mudflat). Figures in parenthesis represent standard errors. *only 1 fish caught. J juvenile and A adult lifestages (based on sizes given by Gomon et al. 1994). From HindelJ and Jenkins (2005) ............................. 25 Table 4. Summary of sampling locations. ** site sampled, but no mangroves present ................... 29 Table S. Summary of the sex ratio, and average length, weight, number of eggs and percentage gonad to body weight.. ......................................................................................... 35 Table 6. Summary of total numbers of fish species sampled at