Comparison of deterministic growth models fitted to length-at-age data of the piked spurdog (Squalus megalops) in south-eastern Australia
J. Matías Braccini A B C , Bronwyn M. Gillanders A , Terence I. Walker B and Javier Tovar-Avila BA Southern Seas Ecology Laboratories, Darling Building DP 418, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
B Primary Industries Research Victoria, PO Box 114, Queenscliff, VIC 3225, Australia.
C Corresponding author. Email: matias.braccini@dpi.vic.gov.au
Marine and Freshwater Research 58(1) 24-33 https://doi.org/10.1071/MF06064
Submitted: 20 April 2006 Accepted: 14 September 2006 Published: 30 January 2007
Abstract
Age and growth estimates of Squalus megalops were derived from the first dorsal fin spine of 452 sharks, ranging from 274 to 622 mm total length. Age bias plots and indices of precision indicated that the ageing method was precise and unbiased. Edge analysis of the enameled surface of whole spines and similarities in the banding pattern deposited in the enameled surface of spines and in spine sections supported the hypothesis of annual band formation. Multiple versions of two growth models were fitted to length-at-age data, from which a two-phase von Bertalanffy model produced the best fit. For males, the change in growth rate corresponded with size-at-maturity, whereas for females, the change was slightly before size-at-maturity. Regardless of the growth model used, growth rate of females (0.034 to 0.098 years–1) was very low, making S. megalops highly susceptible to overexploitation by fisheries.
Additional keywords: age, AIC, Gompertz, Squalidae, von Bertalanffy.
Acknowledgements
We are grateful to P. Risley, G. Richardson and the crew of fishing vessel ‘Nungurner’ for assistance with sample collection, to G. A. McFarlane and colleagues from the Pacific Biological Station and to G. Watson and M. J. Smale from Port Elizabeth Museum at Bayworld for reading a sub-sample of spines, to S. Irvine for comments on ageing techniques, and to M. Araya and V. Troynikov for comments on growth models. This research was supported by an International Postgraduate Research Scholarship and a University of Adelaide Postgraduate Research Scholarship to J.M.B. and an Australian Fisheries Research and Development Corporation grant (FRDC 2002/033) to T.I.W. B.M.G. was supported by an Australian Research Council QEII Research Fellowship. Funding for field and laboratory components was provided by Sea World Research and Rescue Foundation, Project Aware, Royal Zoological Society of New South Wales, Nature Foundation SA (Nature Foundation South Australia) and Royal Zoological Society of South Australia.
Beamish, R. J. , and Fournier, D. A. (1981). A method for comparing the precision of a set of age determinations. Canadian Journal of Fisheries and Aquatic Sciences 38, 982–983.
Buckland, S. T. , Burnham, K. P. , and Augustin, N. H. (1997). Model selection: an integral part of inference. Biometrics 53, 603–618.
| Crossref | GoogleScholarGoogle Scholar |
Campana, S. E. (2001). Accuracy, precision and quality control in age determination, including a review of the use and abuse of age validation methods. Journal of Fish Biology 59, 197–242.
| Crossref | GoogleScholarGoogle Scholar |
Cerrato, R. M. (1990). Interpretable statistical tests for growth comparisons using parameters in the von Bertalanffy equation. Canadian Journal of Fisheries and Aquatic Sciences 47, 1416–1426.
Druffel, E. M. , and Linick, T. W. (1978). Radiocarbon in annual coral rings of Florida. Geophysical Research Letters 5, 913–916.
Hoenig, J. M. , Morgan, M. J. , and Brown, C. A. (1995). Analysing differences between two age determination methods by tests of symmetry. Canadian Journal of Fisheries and Aquatic Sciences 52, 364–368.
Ketchen, K. S. (1975). Age and growth of dogfish Squalus acanthias in British Columbia waters. Journal of the Fisheries Research Board of Canada 32, 43–59.
Maisey, J. G. (1979). Finspine morphogenesis in squalid and heterodontid sharks. Zoological Journal of the Linnean Society 66, 161–183.
Mollet, H. F. , Ezcurra, J. M. , and O’Sullivan, J. B. (2002). Captive biology of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832). Marine and Freshwater Research 53, 531–541.
| Crossref | GoogleScholarGoogle Scholar |
Tucker, R. (1985). Age validation studies on the spines of the spurdog (Squalus acanthias) using tetracycline. Journal of the Marine Biological Association of the United Kingdom 65, 641–651.
von Bertalanffy, L. (1938). A quantitative theory of organic growth (inquiries on growth laws. II). Human Biology 10, 181–213.
Vooren, C. M. (1992). Reproductive strategies of eight species of viviparous elasmobranchs from southern Brazil. Bulletin de la Societe Zoologique de France 117, 303–312.
Walker, T. I. , Hudson, R. J. , and Gason, A. S. (2005). Catch evaluation of target, by-product and by-catch species taken by gillnets and longlines in the shark fishery of south-eastern Australia. Journal of Northwest Atlantic Fishery Science 35, 505–530.
Walker, T. I. , Taylor, B. L. , Hudson, R. J. , and Cottier, J. P. (1998). The phenomenon of apparent change of growth rate in gummy shark (Mustelus antarcticus) harvested off southern Australia. Fisheries Research 39, 139–163.
| Crossref | GoogleScholarGoogle Scholar |
Watson, G. , and Smale, M. J. (1999). Age and growth of the shortnose spiny dogfish Squalus megalops from the Agulhas Bank, South Africa. South African Journal of Marine Science 21, 9–18.
Wilson, C. D. , and Seki, M. P. (1994). Biology and population characteristics of Squalus mitsukurii from a seamount in the Central North Pacific Ocean. Fishery Bulletin 92, 851–864.
Wintner, S. P. (2000). Preliminary study of vertebral growth rings in the whale shark, Rhincodon typus, from the east coast of South Africa. Environmental Biology of Fishes 59, 441–451.
| Crossref | GoogleScholarGoogle Scholar |