Innovative solutions for aquaculture planning and management: addressing seal interactions in the finfish aquaculture industry SD Goldsworthy, B Page, PD Shaughnessy, D Hamer, KD Peters, RR McIntosh, AMM Baylis, J McKenzie South Australian Research and Development Institute SARDI Aquatic Sciences 2 Hamra Avenue West Beach SA 5024 Telephone: (08) 8207 5400 Facsimile: (08) 8207 5481 http://www.sardi.sa.gov.au/ Disclaimer The authors warrant that they have taken all reasonable care in producing this report. The report has been through the SARDI Aquatic Sciences internal review process, and has been formally approved for release by the Chief Scientist. Although all reasonable efforts have been made to ensure quality, SARDI Aquatic Sciences does not warrant that the information in this report is free from errors or omissions. SARDI Aquatic Sciences does not accept any liability for the contents of this report or for any consequences arising from its use or any reliance placed upon it. Copyright Fisheries Research and Development Corporation and South Australian Research and Development Institute 2009. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the author. Printed in Adelaide, July 2009 SARDI Aquatic Sciences Publication Number F2008/000222–1 SARDI Research Report Series Number 288 ISBN Number: 978–0–7308–5391–6 Authors: SD Goldsworthy, B Page, PD Shaughnessy, D Hamer, KD Peters, RR McIntosh, AMM Baylis, J McKenzie Reviewers: Dr M Loo and Dr M Deveney Approved by: Dr Jason Tanner Signed: Date: 24 July 2009 Distribution: FRDC, PIRSA Aquaculture Circulation: Public domain TABLE OF CONTENTS 3 TABLE OF CONTENTS 1 NON TECHNICAL SUMMARY ........................................................................................................6 2 BACKGROUND .............................................................................................................................10 INNOVATIVE SOLUTIONS FOR AQUACULTURE PLANNING AND MANAGEMENT .......................................10 SEAL FINFISH AQUACULTURE INTERACTIONS......................................................................................10 BACKGROUND TO SEAL SPECIES .......................................................................................................13 Australian sea lions (ASL).........................................................................................................13 New Zealand fur seals (NZFS)..................................................................................................15 PROXIMITY OF SEAL COLONIES TO CURRENT FINFISH AQUACULTURE ZONES........................................18 SCOPE OF THE PROJECT ...................................................................................................................19 3 NEED..............................................................................................................................................19 4 AIMS AND OBJECTIVES ..............................................................................................................20 5 REPORT FORMAT ........................................................................................................................21 6 OPERATIONAL INTERACTIONS BETWEEN SEALS AND THE TUNA FARMING INDUSTRY IN PORT LINCOLN.............................................................................................................................22 INTRODUCTION .................................................................................................................................22 METHODS.........................................................................................................................................26 Protection measures used at tuna farms ..................................................................................26 Questionnaire survey of tuna farm operators............................................................................27 Seal and dolphin interactions at finfish cages ...........................................................................27 Counts of seals and dolphins at cages ..............................................................................27 Attacks by seals on caged tuna .........................................................................................28 Trends in the abundance of seals near finfish aquaculture.......................................................29 RESULTS..........................................................................................................................................29 Protection measures used at tuna farms ..................................................................................29 Questionnaire survey of tuna farm operators............................................................................30 Perceived economic significance.......................................................................................30 Trends over time since tuna farming began ......................................................................31 Nature of operational interactions between seals and farmed tuna...................................31 Typical outcomes of interactions: reduced growth and market value ................................34 Seal species responsible ...................................................................................................35 Mitigation measures no longer used..................................................................................35 Mitigation measures currently used ...................................................................................36 Responsibility for coordinating and assessing seal interaction mitigation strategies.........37 Seal and dolphin interactions at finfish cages ...........................................................................37 Counts of marine mammals at finfish cages......................................................................37 Seal attacks at tuna farms .................................................................................................39 Trends in the abundance of seals near finfish aquaculture.......................................................42 DISCUSSION .....................................................................................................................................43 Protection measures used at tuna farms ..................................................................................43 Questionnaire survey of tuna farm operators............................................................................44 Seal and dolphin interactions at finfish cages ...........................................................................45 Counts of marine mammals...............................................................................................45 Seal attacks .......................................................................................................................46 Trends in the abundance of seals near finfish aquaculture.......................................................47 Summary...................................................................................................................................48 Recommendations ....................................................................................................................49 TABLE OF CONTENTS 4 7 AUSTRALIAN SEA LIONS IN SOUTHERN SPENCER GULF AND ON THE COAST OF EYRE PENINSULA, SOUTH AUSTRALIA: ABUNDANCE IN 2004 AND 2005......................................52 BACKGROUND ..................................................................................................................................52 METHODS.........................................................................................................................................53 Study colonies...........................................................................................................................53 Islands in Spencer Gulf and nearby offshore islands................................................................54 Islands of the Nuyts Archipelago...............................................................................................56 Pup counts ................................................................................................................................57 Pup mortality .............................................................................................................................59 Procedure for estimating pup abundance from counts .............................................................59 Mark-recapture estimation of pup numbers ..............................................................................60 Trends in abundance of pups at Dangerous Reef ....................................................................61 Classification of sites used by ASL ...........................................................................................62 RESULTS..........................................................................................................................................63 Australian sea lion pups at sites in the 2004–05 pupping seasons...........................................63 Mark-recapture estimates of pup numbers and comparison with direct counts ........................70 DISCUSSION .....................................................................................................................................79