At this time of year great white sharks are travelling down the the east coast of the South Island on their way to their summer feeding grounds around Stewart Island.
However, it is not known if the great white, of about 4.5m, spotted by two Coromandel Peninsula fishermen this week will come south as photographs show it is not tagged.
Department of Conservation shark specialist Clinton Duffy said the shark was originally thought to be a tagged shark known as Miranda, but closer inspection of photographs showed that what had been thought to be tags was in fact fishing gear.
Information scientists had gathered on the sharks it had tagged in the past three years around Stewart Island showed a number were expected to head south from their winter feeding grounds in the tropics to the island, he said.
In the three years, researchers had tagged 30 great whites and photographically identified 50.
When migrating, the sharks spent 70% of their time at the surface, but if feeding they spent most of their time at the bottom of the ocean.
Of the 32 seen at Stewart Island during a research trip last year, five had been seen in the area previously, he said.
Already this month, one tagged shark had been tracked from Stewart Island to Fiji and back via the east coast.
Studies had shown the sharks had favoured feeding areas in New Zealand, in particular Chatham or Stewart islands.
As there had been no tagging of the sharks off the coast of Otago such as at the Nuggets, the Catlins or Otago Peninsula, it was not known if there was a population that specifically returned to the area, he said.
"It's possible Otago has its own population or they could just be passing through."
The team would be heading back to Stewart Island in March to continue its research, with the hope of tagging and photographically identifying more sharks.
Any sightings of great white sharks could be reported to the department on 0800 362-468.
