1. School of Engineering; The University of Newcastle; Callaghan NSW 2308 Australia
2. James Cook University; College of Marine and Environmental Sciences; Smithfield Qld 4870 Australia
3. Sharks and Rays Australia; P. O. Box 575 Bungalow Qld 4870 Australia
4. Freshwater Fish Group & Fish Health Unit, Centre for Fish & Fisheries Research; Murdoch University; Murdoch WA 6150 Australia