Great white sharks that swim in Australian waters don’t like venturing into the open ocean and tend to stay close to the coast, according to a NZ study.
Great white sharks in waters off the southern Australian coast tend not to venture into the open ocean, instead they prefer to travel up the east or west coasts.
That’s according to a preliminary analysis of 10 years’ worth of data taken from sharks tagged by New Zealand scientists.
Great white sharks in New Zealand waters regularly migrate to the tropics, whereas they found sharks in Australia’s waters don’t like venturing out into the open ocean.
It suggests many sharks spend more time swimming outside of New Zealand’s cold waters than in it.
Other migratory patterns are likely to be revealed when the scientists begin analysing all the data they’ve gathered in the decade they’ve been tagging sharks.
The project is a collaboration between NIWA – the National Institute of Water and Atmospheric Research – and the Department of Conservation.
Since 2005, 95 sharks have been tagged – most in the waters of the Chatham and Stewart Islands.
The tagging shows the sharks travel in a remarkably straight line on their migrations, averaging about 5km/h, or 100km per day, although some have done up to 150km a day.
In the afternoons they also tend to spend time at the surface while making regular dives between 200m and 800m.
“We don’t know why they’re doing that, we assume they’re feeding,” said NIWA fisheries scientist and shark expert 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.”
The aim of the tagging is to find out how mobile the sharks were, how far they travelled and where to, and their habitat requirements.
Dr Francis said they were surprised to discover most sharks migrate to the tropics.
One 3.3m great white named Pip recently entered Queensland’s tropical waters.
Tracking data showing she took 20 days to travel 2020km from the Snares Shelf at the bottom of the South Island to waters near Sydney.