Major Fish Kills in the Northern Rivers of NSW in 2001: Causes, Impacts & Responses

Major Fish Kills in the Northern Rivers of NSW in 2001: Causes, Impacts & Responses

Major Fish Kills in the Northern Rivers of NSW in 2001: Causes, Impacts & Responses Simon Walsh, Craig Copeland and Megan Westlake NSW Department of Primary Industries Ballina Fisheries Centre Ballina NSW 2478 Australia. September 2004 NSW Department of Primary Industries - Fisheries Final Report Series No. 68 ISSN 1449-9967 Major Fish Kills in the Northern Rivers of NSW in 2001: Causes, Impacts & Responses Simon Walsh, Craig Copeland and Megan Westlake NSW Department of Primary Industries Ballina Fisheries Centre Ballina NSW 2478 Australia. September 2004 NSW Department of Primary Industries - Fisheries Final Report Series No. 68 ISSN 1449-9967 Major fish kills in the northern rivers of NSW in 2001: Causes, Impacts & Responses September 2004 Authors: Simon Walsh, Craig Copeland and Megan Westlake Published By: NSW Department of Primary Industries (now incorporating NSW Fisheries) Postal Address: Cronulla Fisheries Centre, PO Box 21, NSW, 2230 Internet: www.fisheries.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. 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 ACKNOWLEDGMENTS...............................................................................................................................II EXECUTIVE SUMMARY...........................................................................................................................III 1. BACKGROUND................................................................................................................5 1.1. Richmond .........................................................................................................................7 1.2. Macleay ............................................................................................................................7 1.3. Clarence............................................................................................................................7 1.4. NSW Fisheries initial response and the involvement of others........................................8 2. MONITORING ...............................................................................................................10 2.1. Water Quality .................................................................................................................10 2.2. Richmond River..............................................................................................................10 2.3. Clarence River ................................................................................................................17 2.4. Macleay River.................................................................................................................18 2.5. General trends.................................................................................................................19 3. CAUSES.........................................................................................................................20 3.1. Wollongbar workshop executive summary ....................................................................20 3.1.1. Introduction ..............................................................................................................20 3.1.2. Time line of rainfall, flood, fish kill and black water ............................................... 20 3.1.3. Impacts of the flood on the lower Richmond River................................................... 21 3.1.4. Contributing factors to loss of dissolved oxygen and development of ‘black water’ 21 3.1.5. Implications for land and water management.......................................................... 22 4. NSW FISHERIES SCIENTIFIC SURVEY SUMMARIES ..................................................24 4.1. Research team monitoring ..............................................................................................24 4.2. Prawn trawl survey.........................................................................................................24 4.3. Richmond Scientific Survey...........................................................................................25 4.4. Macleay Scientific Survey..............................................................................................26 4.5. Richmond Recreational Fishing Survey .........................................................................28 4.6. Macleay Recreational Fishing Survey............................................................................30 4.7. Other Wildlife.................................................................................................................33 5. COMMUNICATIONS......................................................................................................34 5.1. External – Media releases / articles ................................................................................34 5.2. River closures / Compliance Strategy.............................................................................34 5.3. Recovery Committees.....................................................................................................36 5.4. Public Submissions.........................................................................................................36 5.5. Richmond River Public Submission Summary...............................................................37 5.6. Macleay River Public Submission Summary .................................................................37 5.7. Compliance / Effectiveness ............................................................................................38 6. POTENTIAL SOLUTIONS TO FUTURE FISH KILL EVENTS ...........................................40 6.1. North Coast Regional Recovery Coordination Committee ............................................40 6.2. Floodplain management .................................................................................................40 6.3. Current Initiatives...........................................................................................................41 6.4. Suggested strategies to minimise future fish kill events.................................................41 7. SUMMARY OF RECOMMENDATIONS ...........................................................................43 Suggested strategies to minimise future fish kill events ............................................................44 8. REFERENCES................................................................................................................45 APPENDIX 1: RIVER CLOSURES............................................................................................................48 Walsh, Copeland & Westlake 2001 Northern Rivers Fish Killi ii Acknowledgements ACKNOWLEDGMENTS The information contained within has been largely derived from a variety of sources including other reports and memos, minutes of key meetings and media releases. Authors of these works include Megan Westlake, Craig Copeland, Anna Tacey, Marcus Riches, Natalie Taffs, Dr Dave Pollard, Dr Aldo Steffe, Marcus Miller, Will Macbeth, Peter Slavich (NSW Agriculture). Bob Creese, Steve Kennelly and Sarah Fairfull provided useful criticism to early drafts of this report. We thank Graeme Plumb (Ballina Shire Council), Michael Wood (Richmond River County Council), Ron Kemsley (Kempsey Shire Council), and Richard Roper (Maclean Shire Council) for water quality data and Al Lyons for fish kill assessments. 2001 Northern Rivers Fish Kill Walsh, Copeland & Westlake Executive Summaryiii EXECUTIVE SUMMARY Following major flooding in early February 2001 in the upper reaches of the Richmond River catchment, a major fish kill occurred in the Richmond River. Fish kills were also recorded at this time in tributaries of the Tweed and Brunswick Rivers. Subsequent flooding in March 2001 resulted in a major fish kill in the Macleay River and minor fish kills in the Clarence River (see Figure 1). The cause of the fish kills was extremely low dissolved oxygen levels in the rivers; most were below 1 mg/L (well below the limit required for survival by fish of approximately 4 mg/L). This most likely resulted from the death of pasture grasses inundated by floods which removes oxygen from the water and the rapid drainage of this floodplain water into the river. Also acid sulphate soil-derived drainage sediments were also a likely contributor of low dissolved oxygen in the water. Key sources of low oxygen to the system were all areas that were formerly important fish habitats primarily Tuckean Swamp, Rocky Mouth Creek and Bungawalbyn Swamp in the Richmond; Everlasting Swamp, Shark Creek and Coldstream wetlands in the Clarence; and Yarrahapinni, Belmore Swamp, Swan Pool

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