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Evolutionary, molecular and comparative zoology
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RESEARCH ARTICLE
Contents Vol 54(6)

Growth dynamics of freshwater crocodiles (Crocodylus johnstoni) in the Lynd River, Queensland

Anton D. Tucker A E , Colin J. Limpus B , Keith R. McDonald C and Hamish I. McCallum A D
+ Author Affiliations
- Author Affiliations

A Zoology Department, University of Queensland, Brisbane, Qld 4072, Australia.

B Queensland Parks and Wildlife Service, PO Box 155, Brisbane, Qld 4002, Australia.

C Queensland Department of Environment and Heritage, PO Box 975, Atherton, Qld 4883, Australia.

D Present address: School of Zoology, University of Tasmania, Private Bag 5, Hobart, Tas. 7001, Australia.

E Corresponding author. Present address: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA. Email: tucker@mote.org

Australian Journal of Zoology 54(6) 409-415 https://doi.org/10.1071/ZO06099
Submitted: 27 November 2006  Accepted: 27 November 2006   Published: 9 January 2007

Abstract

We analysed growth models for a population of Australian freshwater crocodiles (Crocodylus johnstoni). Competing growth models were tested with two data sets: individuals of known-age, and growth interval data from capture-recapture records. A von Bertalanffy function provided the best empirical fit of several growth models. The estimated asymptotic lengths (snout–vent length of males = 125.3 cm; females = 97.4 cm) agreed well with average lengths of the ten largest males and females in the population. Sexual size dimorphism in this species resulted from a combination of smaller mean length at maturity for females and a subsequent decline in female growth rate. Size dimorphism may result from individual trade-offs in age v. length at maturity as a consequence of sexual selection.


Acknowledgments

The field study was initiated by the Queensland Parks and Wildlife Service (QPWS). We thank the many volunteers who helped to capture and process crocodiles between 1976 and 1995. Owners of Springfield, Burlington and Amber Stations granted access to the study site. The study received support from the Australian Research Council, the Centre for Conservation Biology at the University of Queensland, and an Overseas Postgraduate Research Scholarship to A. Tucker. Studies were conducted under permits from QPWS and with animal ethics approval from the University of Queensland. G. Webb and B. Magnusson provided constructive criticism on early versions of the manuscript.


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