Retained fishing gear and associated injuries in the east Australian grey nurse sharks (Carcharias taurus): implications for population recovery
C. S. Bansemer A B and M. B. Bennett AA School of Biomedical Sciences, University of Queensland, St Lucia, Qld 4072, Australia.
B Corresponding author. Email: carley.bansemer@uqconnect.uq.edu.au
Marine and Freshwater Research 61(1) 97-103 https://doi.org/10.1071/MF08362
Submitted: 27 December 2008 Accepted: 11 June 2009 Published: 29 January 2010
Abstract
Incidental hooking of Carcharias taurus is a threat to their populations’ recovery on the east coast of Australia. Photo-identification techniques were used to investigate the frequency of hooking at 25 aggregation sites along the east coast of Australia between 2006 and 2008. Of the 673 sharks identified, 113 sharks were identified with signs of 119 incidences of hooking. For sharks with both their left and right flank photographed during a single survey day, up to 29% of females and 52% of males were identified with retained fishing gear or an attributed jaw injury. The largest number of sharks identified (222) were from a year-round aggregation of immature and mature sharks at Fish Rock, New South Wales, Australia. Forty-eight per cent of all sharks identified with retained fishing gear were first identified at this site. Fish Rock, a designated critical habitat for C. taurus, allows most forms of line fishing except fishing with bait or wire trace while anchored or moored. As interactions with fishing gear can result in debilitating disease, morbidity and death, the high incidence of hooked individual C. taurus is considered a key threatening process that is likely to reduce this shark population’s ability to recover.
Acknowledgements
We acknowledge and thank the editor and referees (including Dr C. Huveneers) for their time and constructive comments. We thank A. Kilpatrick, D. Harasti, P. and N. Hitchens, D. Biddulp, P. Heuttner, K. Holzheimer, A. Nel, K. and C. Phillips, A. Walsh, W. Roberts, R. Peterlin, P. Simpson, M. and D. Davey, V. Temple, T. Starr, M. Jordan, D. Arthur, D. Siviero, D. Bowden and the numerous other volunteer divers, dive shops and clubs for their support, field assistance and images of C. taurus. Financial support was provided by the Hermon Slade Foundation and the Queensland Government PhD Smart State Initiative. In-kind support was provided by W. Lancaster of ZSPORTS, R. Peterlin and the Jervis Bay Dive Club, Ron Henry and the ANU Scuba Club, Underwater World (Mooloolaba), and Australia Zoo. This research was conducted in accordance with University of Queensland Ethics Approval SBMS/196/04/DEH, SBMS/228/05/DEH, SBMS/560/06/DEH and SBMS/640/07/HSF.
Bansemer, C. S. , and Bennett, M. B. (2008). Multi-year validation of photographic identification of grey nurse sharks, Carcharias taurus, and applications for non-invasive conservation research. Marine and Freshwater Research 59, 322–331.
| Crossref | GoogleScholarGoogle Scholar |
Borucinska, J. , Martin, J. , and Skomal, G. (2001). Peritonitis and pericarditis associated with gastric perforation by a retained fishing hook in a blue shark. Journal of Aquatic Animal Health 13, 347–354.
| Crossref | GoogleScholarGoogle Scholar |
Dicken, M. L. , Booth, A. J. , and Smale, M. J. (2007). Spatial and seasonal distribution patterns of juvenile and adult raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa. Marine and Freshwater Research 58, 127–134.
| Crossref | GoogleScholarGoogle Scholar |
Ferretti, F. , Myers, R. A. , Serena, F. , and Lotze, H. K. (2008). Loss of large predatory sharks from the Mediterranean Sea. Conservation Biology 22, 952–964.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Lucifora, L. O. , Menni, R. C. , and Escalante, A. H. (2002). Reproductive ecology and abundance of the sand tiger shark, Carcharias taurus, from the southwestern Atlantic. ICES Journal of Marine Science 59, 553–561.
| Crossref | GoogleScholarGoogle Scholar |
Otway, N. M. , Bradshaw, C. J. A. , and Harcourt, R. G. (2004). Estimating the rate of quasi-extinction of the Australian grey nurse shark (Carcharias taurus) population using deterministic age-and stage-classified models. Biological Conservation 119, 341–350.
| Crossref | GoogleScholarGoogle Scholar |
Smale, M. J. (2002). Occurrence of Carcharias taurus in nursery areas of the Eastern and Western Cape, South Africa. Marine and Freshwater Research 53, 551–556.
| Crossref | GoogleScholarGoogle Scholar |