A great white shark. Photo / SkyTV
The hunt for a mega shark believed to be roaming the coast of New Zealand is still on.
Local fishermen have been telling tales of a great white shark larger than a boat - some say up to 9.4m - just off Stewart Island.
Last year terrifying video footage of a mega shark apparently attacking a tiny boat near Picton made waves online.
Now Australian shark expert Dr Jonathan Werry resumes the search for the monsters of the deep in the Discovery Channel's Shark Week series, which kicks off tonight.
In the opening episode Isle of Jaws the marine biologist and his team investigate the strange disappearance of great white sharks from Neptune island, off South Australia.
They set out to find out where the giant creatures have gone, while trying to solve two of the most closely-guarded of all the species' secrets - where they mate and where they have their young.
Werry believes some oversized great white sharks, including the fabled mega shark, could have ended up here as they migrate across vast distances.
What is believed to be the largest great white shark measured reliably was caught off Western Australia, at Ledge Point, in 1984, Werry said. This shark was measured at 6m - but even bigger creatures are thought to be patrolling the freezing waters of the Foveaux Strait.
"It is possible that some white sharks may have migrated to New Zealand from the Neptune Islands," he said. "Shark movements are not random. They know where they are going and they move in relation to specific environmental and social cues.
"It is quite possible that white sharks responded to one of these cues resulting in a prolonged absence of sharks at the Neptune Islands."
Prior to the absence of white sharks, several killer whales cornered and killed a white shark close to the islands, off the coast near Adelaide, he explained.
"Killer whales are the ultimate top level predator in the ocean's surface waters. White sharks may have been responding to this 'life-threatening' cue and fleeing the area."
Werry and his team have been developing techniques to follow the movements of the creatures in the open ocean.
"We know that juvenile and adult white sharks in New Zealand do visit Australia and then return to New Zealand. Likewise, quite a few white sharks tagged in Australia will visit New Zealand.
"Hence there is a constant 'connection' of white sharks between the two countries and there does seem to be patterns where white sharks will visit and return to specific locations or 'hotspots'."
Werry is confident if there is a mega shark lurking out there, new technology will eventually find it and also give people a shark's-eye view of the deep.
"Tracking technologies are advancing quite rapidly," he said. "It won't be long before we have sophisticated satellite tags that can last several years which also have live cameras that stream constant images of what the shark is seeing as it moves."
*Isle of Jaws opens Shark Week on the Discovery Channel at 8.30pm tonight.