KEY POINTS:
A great white shark's record-breaking swim between New Zealand and Australia could be far more impressive than previously thought.
The 4.4m shark, nicknamed Kerri, started its journey at Stewart Island in March.
An electronic tag attached to its dorsal fin came off 3000km away, near the Great Barrier Reef, two weeks ago.
The journey is the longest ever recorded by a shark from New Zealand. But Department of Conservation scientist Clinton Duffy said it could have been thousands of kilometres longer.
"I would say it's unlikely it would have been a direct route with her being at large for nine months. She could have been all over the place."
Duffy said sharks were known to travel up to 1000km a week.
After being tagged, he said Kerri could have gone to the Chatham Islands or the Auckland Islands.
She could have travelled up the east coast of New Zealand and up to New Caledonian waters in search of food, or she could have swum across to Australia and then up and down the coast before the tag detached from her fin.
"A shark can go for one-and-a-half months on a 30kg piece of blubber," said Duffy.
"On one good meal she could go anywhere in the south-west Pacific."
Great whites are protected in Australia and New Zealand, and scientists are keen to learn more about their migratory habits to identify the risks they face - mostly from fishing fleets.
Duffy said there was a "reasonable population" of mostly juvenile great whites in the seas around Auckland, particularly in the Manukau and Kaipara harbours.
He said the work being carried out would increase knowledge of what was a "very, very poorly known animal".
He plans to keep an eye out for Kerri in Stewart Island in March, when he hoped she might return as part of a breeding and feeding cycle.
"She has some distinctive scars, including an old hook mark and big slashes down her back. She should be fairly recognisable."
