The effects of net fishing: addressing biodiversity and bycatch issues in Queensland inshore waters by Ian Halliday1 Janet Ley2, Andrew Tobin3 Rod Garrett4, Neil Gribble4 and David Mayer5 1Queensland Department of Primary Industries, Agency for Food and Fibre Sciences, Fisheries and Aquaculture, Southern Fisheries Centre, PO Box 76, Deception Bay, Qld. 4508, Australia. 2Australain Institute of Marine Sciences, PMB No 3, Townsville Qld 4810. Current Address:Australian Maritime College, Faculty of Fish and Environment, PO Box 21, Beaconsfield TAS 7270 3Queensland Department of Primary Industries, Agency for Food and Fibre Sciences, Fisheries and Aquaculture, Oonoomba Research Centre PO Box 1085 Townsville 4801 Current Address: CRC Reef Centre, James Cook University, Townsville 4812. 4Queensland Department of Primary Industries, Agency for Food and Fibre Sciences, Fisheries and Aquaculture, Northern Fisheries Centre, PO Box 5396 Cairns, 4870. 5Queensland Department of Primary Industries, Agency for Food and Fibre Sciences, Queensland Beef Industry Institute, Locked Mail Bag 4, Yeerongpilly, 4105. FRDC Project No. 97/206 October 2001 ISBN 0 7345 0150 1 ii QO01022 ISSN 0727-6281 AGDEX 475/10 ISBN 0 7345 0150 1 Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries, Queensland, has taken all reasonable steps to ensure that the information contained in this publication is accurate at the time of production. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter. ISBN 0 7345 0150 1 ª The State of Queensland, Department of Primary Industries, and the Fisheries Research and Development Corporation, 2001. Copyright protects this publication. Except for purposes permitted by the Copyright Act, reproduction by whatever means is prohibited without prior written permission of the Department of Primary Industries, Queensland, and the Fisheries Research and Development Corporation. Inquiries should be addressed to: Southern Fisheries Centre Department of Primary Industries PO Box 76 Deception Bay Qld 4508 iii CONTENTS 1. NON-TECHNICAL SUMMARY ................................................................................................................1 2. BACKGROUND...............................................................................................................................................4 3. NEED ...................................................................................................................................................................6 4. OBJECTIVES ...................................................................................................................................................7 5. ACHIEVEMENT OF OBJECTIVES .........................................................................................................8 6. CATCH CHARACTERIS TICS OF QUEENSLAND INSHORE NET FISHERIES ................ 10 6.1 INTRODUCTION.............................................................................................................................................10 6.2 METHODS FOR DETERMINING CATCH COMPOSITION OF QUEENSLAND INSHORE FISHERIES.............10 6.2.1 Logbook program............................................................................................................................ 10 6.2.2 Observer Program........................................................................................................................... 11 6.2.3 Data Analysis................................................................................................................................... 11 6.3 RESULTS OF OBSERVER AND LOGBOOK PROGRAMS..............................................................................11 6.3.1 Southern Logbook Returns............................................................................................................. 11 6.3.2 Sea Mullet Fishery in Southern Queensland.............................................................................. 12 6.3.2.1 Logbook Program in the Sea Mullet Fishery .................................................................................12 6.3.2.2 Observer Program in the Sea Mullet Fishery.................................................................................14 6.3.2.3 Seasonality of catch in Sea Mullet Fishery ....................................................................................16 6.3.3 Whiting Fisheries in Southern Queensland................................................................................. 17 6.3.3.1 Logbook Program in the Whiting Fishery......................................................................................18 6.3.3.2 Observer Program in the Whiting Fishery .....................................................................................19 6.3.3.3 Seasonality of bycatch in the Whiting Fishery...............................................................................21 6.3.4 Small Mackerel Fisheries in Southern Queensland................................................................... 23 6.3.4.1 Logbook Program in the southern Small Mackerel Fishery...........................................................23 6.3.4.2 Observer Program in the southern Small Mackerel Fishery ..........................................................24 6.3.5 Tropical East Coast Barramundi Fishery................................................................................... 26 6.3.5.1 Logbook Program in the East Coast Barramundi Fishery..............................................................26 6.3.5.2 Observer Program in the East Coast Barramundi Fishery .............................................................26 6.3.6 Tropical East Coast “Mixed Estuary” Fishery.......................................................................... 28 6.3.6.1 Logbook Program in the East Coast “Mixed Estuary” Fishery......................................................28 6.3.6.2 Observer Program in the East Coast “Mixed Estuary” Fishery .....................................................29 6.3.6.3 Mesh Effects...................................................................................................................................30 6.3.7 Gulf of Carpentaria Set Net Barramundi and “Mixed Estuary” Fisheries........................... 31 6.3.7.1 Logbook Program in the Gulf of Carpentaria Barramundi Fishery ...............................................32 6.3.7.2 Observer Program in the Gulf of Carpentaria Barramundi Fishery ...............................................33 6.3.7.3 Logbook Program in the Gulf of Carpentaria Mixed Estuary Fishery...........................................34 6.3.7.4 Observer Program in the Gulf of Carpentaria Mixed Estuary Fishery...........................................34 6.3.7.5 Locality and Seasonal Effects in Gulf of Carpentaria Fisheries. ...................................................35 6.4 DISCUSSION OF BYCATCH IN NET FISHERIES..........................................................................................38 7. FATE OF FINFISH DISCARDED FROM NET CATCHES ........................................................... 41 7.1 METHODS FOR DETERMINING THE FATE OF DISCARDED BYCATCH......................................................41 7.2 RESULTS OF FATE OF DISCARDED BYCATCH..........................................................................................42 7.2.1 Southern Fish Species..................................................................................................................... 42 7.2.2 Tropical Inshore Net fisheries....................................................................................................... 43 7.2.2.1 Observed fate of discarded fish from Tropical East Coast Fisheries .............................................43 7.2.2.2 Observed fate of discarded fish in the Gulf of Carpentaria Fisheries ............................................44 8. FISHERY-INDEPENDENT SAMPLING.............................................................................................. 46 8.1 METHODS......................................................................................................................................................46 8.1.1 Site Selection Procedures............................................................................................................... 46 8.1.2 Characteristics of the research nets............................................................................................. 46 8.1.3 Sampling periods............................................................................................................................. 46 8.1.4 Sampling Regime ............................................................................................................................. 47 8.1.5 Checking Nets................................................................................................................................... 49 iv 8.1.6 Fish Removal and Identification................................................................................................... 49 8.1.7 Design of sampling program......................................................................................................... 49 8.1.8 Environmental Parameters...........................................................................................................