Fish communities of the Lower Murray-Darling catchment: Status and trends Dr Dean Gilligan NSW Department of Primary Industries Narrandera Fisheries Centre Buckingbong Road, Narrandera, NSW 2700 Australia Lower Murray-Darling Catchment Management Authority Project No. MD 005.03 December 2005 NSW Department of Primary Industries – Fisheries Final Report Series No. 83 ISSN 1449-9967 Integrated Fish Monitoring Project Fish communities of the Lower Murray-Darling catchment: Status and trends December 2005 Author: Gilligan, D. M. Published By: NSW Department of Primary Industries (now incorporating NSW Fisheries) Postal Address: Cronulla Fisheries Centre, PO Box 21, NSW, 2230 Internet: www.dpi.nsw.gov.au NSW Department of Primary Industries This work is copyright. Except as permitted under the Copyright Act, no part of this reproduction 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. Cover photo credits: Gunther Schmida –golden perch, fly-specked hardyhead, Murray-Darling rainbowfish, Murray cod, Australian smelt, carp-gudgeon, bony herring, silver perch and freshwater catfish. Ian Wooden – common carp. Rob Rolls – river scene. DISCLAIMER The publishers do not warrant that the information in this report is free from errors or omissions. The publishers do not accept any form of liability, be it contractual, tortuous or otherwise, for the contents of this report for any consequences arising from its use or any reliance placed on it. The information, opinions and advice contained in this report may not relate to, or be relevant to, a reader’s particular circumstance. ISSN 1449-9967 (Note: Prior to July 2004, this report series was published as the ‘NSW Fisheries Final Report Series’ with ISSN number 1440-3544) Contents i TABLE OF CONTENTS TABLE OF CONTENTS................................................................................................................I LIST OF TABLES .......................................................................................................................III LIST OF FIGURES ..................................................................................................................... IV ACKNOWLEDGEMENTS......................................................................................................... VI NON-TECHNICAL SUMMARY ..............................................................................................VII 1. INTRODUCTION .................................................................................................................12 1.1. PREVIOUS FISH RESEARCH IN THE LOWER MURRAY-DARLING CMA AREA.......................16 2. SITE SELECTION, SAMPLING PROTOCOL AND DATA MANAGEMENT............19 2.1. SITE SELECTION ...................................................................................................................19 2.1.1. Randomly selected monitoring sites.........................................................................19 2.2. SAMPLING PROCEDURE........................................................................................................24 2.2.1. Riverine sites............................................................................................................24 2.2.2. Lake & Reservoir sites .............................................................................................24 2.2.3. Wetland sites ............................................................................................................25 2.2.4. Habitat assessment...................................................................................................25 2.3. DATA ENTRY AND QUALITY ASSURANCE ............................................................................25 3. STATUS OF FISH COMMUNITIES OF THE LOWER MURRAY-DARLING CATCHMENT IN 2004 ........................................................................................................26 3.1. INTRODUCTION ....................................................................................................................26 3.2. METHODS.............................................................................................................................27 3.3. RESULTS ..............................................................................................................................29 3.3.1. Catch data................................................................................................................29 3.3.2. Analysis of fish communities among zones ..............................................................33 3.3.3. 2004 benchmark of fish communities in the Lower Murray-Darling catchment .....35 3.3.3.1. Species richness...............................................................................................35 3.3.3.2. Total abundance ..............................................................................................35 3.3.3.3. Total biomass ..................................................................................................35 3.3.3.4. Shannon’s Diversity H and evenness J............................................................35 3.3.3.5. Proportion native fish......................................................................................35 3.3.3.6. Proportion of recruits ......................................................................................43 3.3.3.7. Proportion of individuals with a health condition...........................................43 3.3.5.7 Power analyses .......................................................................................................43 3.4. DISCUSSION .........................................................................................................................46 4. STATUS OF INDIVIDUAL SPECIES IN THE LOWER MURRAY-DARLING CATCHMENT IN 2004 ........................................................................................................49 4.1. INTRODUCTION ....................................................................................................................49 4.2. METHODS.............................................................................................................................50 4.3. RESULTS AND DISCUSSION ..................................................................................................50 4.3.1. Proportion of catch ..................................................................................................50 4.3.2. Proportion of biomass..............................................................................................52 4.3.3. Proportion of sites....................................................................................................52 4.3.4. Proportion recruits ..................................................................................................52 Fish in the Lower Murray-Darling, Gilligan ii Contents 5. TRENDS IN FISH COMMUNITIES AND FISH SPECIES IN THE LOWER MURRAY-DARLING CATCHMENT FROM 1994 – 2005: ANALYSIS OF STANDARDISED ELECTROFISHING DATA ............................................................... 55 5.1. INTRODUCTION ................................................................................................................... 55 5.2. METHODS............................................................................................................................ 56 5.2.1. Data......................................................................................................................... 56 5.2.2. Data analysis........................................................................................................... 56 5.3. RESULTS.............................................................................................................................. 56 5.3.1. Fish community parameters.................................................................................... 56 5.3.2. Individual species.................................................................................................... 57 5.4. DISCUSSION ........................................................................................................................ 59 6. TRENDS IN THE HARVEST OF FISH SPECIES FROM THE LOWER MURRAY- DARLING CATCHMENT BETWEEN 1955 AND 2001: THE INLAND COMMERCIAL FISHERY................................................................................................. 61 6.1. INTRODUCTION ................................................................................................................... 61 6.2. DATA ANALYSIS.................................................................................................................. 62 6.3. RESULTS AND DISCUSSION ................................................................................................. 63 6.3.1. Golden perch........................................................................................................... 64 6.3.2. Carp......................................................................................................................... 64 6.3.3. Murray cod.............................................................................................................. 67 6.3.4. Silver perch ............................................................................................................. 68 6.3.5. Redfin perch ...........................................................................................................