Fish communities and migration in the Shoalhaven River – Before construction of a fishway P. C. Gehrke, D. M. Gilligan and M. Barwick NSW Fisheries Office of Conservation Port Stephens Fisheries Centre Taylors Beach, NSW, 2316 Australia January 2001 NSW Fisheries Final Report Series No. 26 ISSN 1440-3544 Contents i TABLE OF CONTENTS TABLE OF CONTENTS................................................................................................................. 1 LIST OF TABLES .........................................................................................................................III LIST OF FIGURES .......................................................................................................................IV ACKNOWLEDGEMENTS...........................................................................................................VI NON-TECHNICAL SUMMARY ............................................................................................... VII CONDITION OF FISH COMMUNITIES WITHIN THE SHOALHAVEN RIVER SYSTEM. ........................VIII MIGRATORY BEHAVIOUR OF AUSTRALIAN BASS AND STRIPED MULLET.......................................IX FINE-SCALE DISTRIBUTIONS OF FISH BELOW TALLOWA DAM AND CONSIDERATIONS FOR FISHWAY DESIGN. ..........................................................................................................................IX RECOMMENDATIONS ...................................................................................................................... X 1. INTRODUCTION.................................................................................................................... 1 1.1. FISHWAYS AND FISH PASSAGE IN NEW SOUTH WALES ...................................................... 2 1.1.1. Definition and ecological significance .......................................................................... 2 1.1.2. Fish migration................................................................................................................ 2 1.1.3. Types of barriers ............................................................................................................ 3 1.1.4. Fishways......................................................................................................................... 3 1.1.5. Current management...................................................................................................... 5 1.1.6. Recent NSW Fisheries research..................................................................................... 5 1.1.7. Future needs................................................................................................................... 6 2. METHODS ............................................................................................................................... 7 2.1. STUDY DESIGN.................................................................................................................... 7 2.2. (I) PRE CONSTRUCTION ASSESSMENT OF FISH COMMUNITIES ............................................ 7 2.2.1. Sampling methods ..........................................................................................................7 2.3. (II) RADIO TELEMETRY METHODS ...................................................................................... 9 2.3.1. Surgical procedures ..................................................................................................... 10 2.3.2. Telemetry procedures................................................................................................... 10 3. CHANGES IN FISH COMMUNITIES OF THE SHOALHAVEN RIVER 20 YEARS AFTER CONSTRUCTION OF TALLOWA DAM, AUSTRALIA. ......................................... 11 3.1.1. Summary....................................................................................................................... 11 3.2. INTRODUCTION ................................................................................................................. 11 3.3. METHODS ......................................................................................................................... 12 3.3.1. Sites .............................................................................................................................. 12 3.3.2. Sampling methods ........................................................................................................ 13 3.3.3. Reconstruction of pre-dam fish assemblages............................................................... 13 3.3.4. Analytical methods....................................................................................................... 13 3.4. RESULTS ........................................................................................................................... 17 3.4.1. Reconstructed fish assemblages................................................................................... 17 3.4.2. Present-day fish assemblages ...................................................................................... 17 3.4.3. Spatial variation among sites....................................................................................... 21 3.4.4. Temporal differences between historical and contemporary assemblages ................. 27 3.5. DISCUSSION ...................................................................................................................... 27 Tallowa Dam High Fishway Project, Gehrke, Gilligan and Barwick Contents ii 4. MOVEMENTS OF AUSTRALIAN BASS (Macquaria novemaculeata) AND STRIPED MULLET (Mugil cephalus) IN THE SHOALHAVEN RIVER, ASSESSED USING RADIO TELEMETRY. ............................................................................................................................... 33 4.1.1. Summary....................................................................................................................... 33 4.2. INTRODUCTION ................................................................................................................. 33 4.3. METHODS ......................................................................................................................... 35 4.3.1. Species selection .......................................................................................................... 35 4.3.2. Telemetry system..........................................................................................................35 4.3.3. Surgical procedures ..................................................................................................... 35 4.3.4. Telemetry procedures................................................................................................... 36 4.3.5. Analytical methods....................................................................................................... 36 4.4. RESULTS ........................................................................................................................... 38 4.5. DISCUSSION ...................................................................................................................... 45 4.5.1. Australian bass............................................................................................................. 46 4.5.2. Striped mullet ............................................................................................................... 46 4.5.3. Implications for future study........................................................................................ 47 4.5.4. Implications for fishway design ................................................................................... 47 5. FINE-SCALE FISH DISTRIBUTIONS BELOW TALLOWA DAM AND CONSIDERATIONS FOR FISHWAY DESIGN. ...................................................................... 49 5.1.1. Summary....................................................................................................................... 49 5.2. INTRODUCTION ................................................................................................................. 49 5.2.1. High Fishways.............................................................................................................. 50 5.2.2. Fishway design considerations .................................................................................... 50 5.3. METHODS ......................................................................................................................... 51 5.3.1. Sites .............................................................................................................................. 51 5.3.2. Sampling....................................................................................................................... 51 5.3.3. Analytical methods....................................................................................................... 51 5.4. RESULTS ........................................................................................................................... 53 5.4.1. Size range of species within the system........................................................................ 53 5.4.2. River flow at Baron Flat (500m downstream of Tallowa Dam). ................................. 53 5.4.3. Water quality................................................................................................................ 53 5.4.4. Distribution of fish below the dam wall....................................................................... 53 5.5. DISCUSSION .....................................................................................................................