Demersal finfish resource assessment survey of the north-west slope of Western Australia Stephen J. Newman and David Evans �\l�M£,v o��I >- c.,�·f/ 0,(\ �--•( < (11� , ::; "';.� -<.�� ��NAU"> Department of Fisheries Project No. 1998/152 December, 2002 ISBN No. 1 877098 23 X FRDC Project 1998/152 FRDC Project 1998/152 – Demersal finfish resource assessment survey of the north- west slope of Western Australia Stephen J. Newman and David Evans Western Australian Marine Research Laboratories PO Box 20, North Beach WA 6920 Phone 9246 8444 Fax 9447 3062 Published by the Department of Fisheries – Research Division, Western Australia ISBN 1 877098 23 X August 2003 © 2002 Fisheries Research and Development Corporation and Department of Fisheries – Research Division, Western Australia This work is copyright. 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Printed by Department of Fisheries – Research Division, Western Australia. 2 FRDC Project 1998/152 Table of Contents Table of Contents ..................................................................................................................... 3 Objectives: ................................................................................................................................ 4 Non-Technical Summary: ....................................................................................................... 4 Outcomes Achieved ............................................................................................................................................ 4 Acknowledgements .................................................................................................................. 8 Background .............................................................................................................................. 9 Need ......................................................................................................................................... 11 Objectives .............................................................................................................................................. 12 Methods ................................................................................................................................... 13 Survey area and restrictions .............................................................................................................................. 13 Survey Permits – Trawlers ............................................................................................................................... 14 Survey Permits – Trap and Line vessels ........................................................................................................... 14 Vessels and Gear .............................................................................................................................................. 15 Trawlers .............................................................................................................................................. 15 Trap and Line vessels ....................................................................................................................................... 16 Fishing Practices .............................................................................................................................................. 17 Catch Recording .............................................................................................................................................. 18 Results ..................................................................................................................................... 21 Survey Effort and Distribution ......................................................................................................................... 21 Trawl Effort .............................................................................................................................................. 22 Trawl Distribution ............................................................................................................................................ 22 Trap and Line Effort ......................................................................................................................................... 22 Trap and Line Distribution ............................................................................................................................... 23 Trawl Catch .............................................................................................................................................. 23 Trap and Line Catch ......................................................................................................................................... 26 Length Frequency Data .................................................................................................................................... 27 Discussion ............................................................................................................................... 30 Benefits .................................................................................................................................... 34 Further Development ............................................................................................................ 34 Planned Outcomes ................................................................................................................. 35 Conclusion .............................................................................................................................. 35 References ............................................................................................................................... 36 Appendices .............................................................................................................................. 37 Appendix 1: Intellectual Property ................................................................................................................... 37 Appendix 2: Staff ........................................................................................................................................... 37 Appendix 3: Provisional species list of the fish fauna from deep slope waters off the north-west coast of Western Australia (includes common names, Australian Aquatic Biota Codes [CAAB] - Yearsley et al., 1997; Rees et al., 1999 and preferred common names if different). ................. 38 3 FRDC Project 1998/152 1998/152 Demersal finfish resource assessment survey of the north-west slope of Western Australia Principal Investigator: Dr. Stephen Newman Address: Department of Fisheries Fisheries Research Division PO Box 20 North Beach, WA, 6920 Telephone: 08 9246 8444 Fax: 08 9447 3062 Objectives: 1. To determine the species distributions and composition of demersal scalefish resources on the NW slope and to examine industry collected catch and effort data to determine an index of relative abundance. 2. To assess the viability of exploiting the demersal scalefish resource of the North-West slope using (a) fish trawls, traps and lines in the western zone (west of 120°E longitude) and; (b) traps and lines in the eastern zone (east of 120°E longitude).. 3. To gather biological information on the major species (e.g. to investigate longevity, natural mortality and aspects of their reproductive biology). Non-Technical Summary: Outcomes Achieved This project was not completed due a limited number of commercial size landings. Given the high cost of undertaking survey work in the deep water regions of north-western Australia, it is advisable that any further development be co-operative joint ventures among fishing companies in order to share both the cost of survey work and the knowledge generated. More importantly funding will be required to cover fuel costs and other overheads when commercial landings are limited. However, one of the outcomes from this project is a proposed developmental zone to be created for deep slope waters to facilitate further development. 4 FRDC Project 1998/152 The nature and extent of demersal finfish resources in deep slope waters (>200m) off the northwest coast of Western Australia are poorly understood. Existing fish trawl, trap and line fishing effort is concentrated in shallower waters (<200m), while trawling in deep slope waters (>200m) exclusively targets crustaceans. Despite significant initial levels of interest in this project, poor commercial catches contributed to fishers returning to grounds in shallower waters on the shelf. As a consequence of the lack of significant commercial catches in the deep