Collaborative photo-identification and monitoring of grey nurse sharks (Carcharias taurus) at key aggregation sites along the eastern coast of Australia
Sean M. Barker A B and Jane E. Williamson AA Marine Ecology Group, Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
B Corresponding author. Email: seanmbarker@hotmail.com
Marine and Freshwater Research 61(9) 971-979 https://doi.org/10.1071/MF09215
Submitted: 3 September 2009 Accepted: 1 February 2010 Published: 23 September 2010
Abstract
Before the worldwide decline of the ‘globally vulnerable’ Carcharias taurus may be addressed, an understanding of its migratory patterns and locations, and/or times when sharks may be vulnerable, is required to identify habitats that are critical to its survival. A collaborative framework for photo-identification and monitoring of C. taurus may greatly assist with conservation management initiatives. Images of C. taurus were sourced from public submissions to the www.spotashark.com (verified 12 February 2009) website and during targeted surveys. A computer-assisted program (I3S) was used to match the images of sharks photographically from the database. Research revealed patterns of movement, site utilisation and population structure similar to those in previous tagging studies. With the use of an underwater camera and two laser-scaling devices, 408 individual sharks were identified. Average occupancy times at two locations in New South Wales (NSW), Australia, were 308 days (Fish Rock) and 363 days (Magic Point). Seventeen individuals undertook northward or southward movements, averaging 350 km. The present study showed that a broad-based technique for data acquisition, coupled with rigorous evaluation of photographic identifications can provide support for local research and management programs and may aid with the conservation of the C. taurus species worldwide.
Additional keywords: mark resighting, migration, philopatry, photo-ID, photographic database.
Acknowledgements
We thank Pro Dive Manly, Cardno Ecology Laboratory Pty Ltd, Eco Divers, contributing photographers and dive teams and members of the Marine Ecology Group at Macquarie University for their invaluable assistance in the field. Thanks also go to Vic Peddemors and Marcus Lincoln Smith for advice that greatly improved the quality of our research, and to Andrew Boulton and two anonymous referees who provided invaluable feedback on this manuscript. This research was funded by NSW DPI, a FRC Research Award, an AMSA student Award and Macquarie University. Special thanks go to Peter Simpson for his financial assistance with setting up the www.spotashark.com website. This research was conducted in accordance with the Animal Ethics Committee Research Office at Macquarie University (Reference number: 2006/008) and complies with current occupational diving laws in Australia. Thanks also go to all the contributing photographers involved in the Spot-A-Shark project, with special thanks to Peter and Kevin Hitchins (South West Rocks Dive Centre), Robin Nagy, Anita Roche, Peter McGee and Jeremy Weinman, whose images were used in this publication (see Accessory Publication to this paper). Thanks also go to Mark Gray, Paul Krattiger, Nicci Kershler, Nigel Coombes, Don Silcock, Silke Stuckenbrock, Dave Thomas, Jayne Jenkins, Lynda Clarke, the Underwater Research Group (URG), Eco Divers and the Ryde Underwater Club. We would like to acknowledge Phil Bowman who started an earlier manual spot recognition project to monitor the eastern population of the Australian grey nurse shark in 1987.
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