Study tracks the secret life of sharks

A ten year study peeking into the private lives of New Zealand sharks has answered some questions about where they travel and what they do, but also raised new ones, say researchers.

The shark tagging and tracking project undertaken by NIWA and the Department of Conservation (DOC) has been running since 2005 and followed the moment of 95 sharks mostly tagged around Stewart Island and the Chathams.

NIWA scientist Malcolm Francis tagging white shark with acoustic tag. [Warrick Lyon/NIWA]
NIWA scientist Malcolm Francis tagging white shark with acoustic tag. [Warrick Lyon/NIWA]

The study, which is entering its final data analysis stage, has revealed some interesting insights into the behaviour of sharks. One of the first discoveries was that most sharks migrate to the warmer tropics during the winter. Three dimensional tracking of the sharks also showed they travel in a remarkably straight line on their migrations,  up to 150km a day. In the afternoons they tend to spend time at the surface but also make regular dives between 200 and 800m – the record depth is 1246m.

“We don’t know why they’re doing that, we assume they’re feeding.” said shark Scientist Malcolm Francis. “We also don’t know how they navigate in a straight line or why. It’s a big puzzle and not one we are likely to work out.

“While we’ve found out some answers to some questions, our work has also raised a series of other questions. We’ve found out about the large scale, and where and when they hang out around northern Stewart Island, but not what they do close to mainland New Zealand.”

You read more about the research programme, and watch video of the sharks on the NIWA website.

The NIWA and DOC shark research has been covered widely in the New Zealand media: Shark study reveals ‘surprising discoveries’
Otago Daily Times: Shark hunt a life-saver
TVNZ News: Decade-long shark study reveals secret lives
Dunedin Television: Great white sharks project coming to an end
The Southland Times: Ten year shark study comes to an end
Radio New Zealand News: Shark tags track great whites to tropics
Newstalk ZB: NZ’s great white sharks only part time Kiwis
MSN NZ News: Sharks prefer tropics over NZ waters
3 News: Great white sharks take tropical holiday