THE incredible travels of a hefty great white shark named Pip are helping scientists rewrite the book on everything we thought we knew about the feared species.
In 15 months, Dr Malcolm Francis and his colleagues at Niwa and the Department of Conservation have tracked the 3.3m female from Stewart Island to the warmer waters of the Queensland coast, and back again.
She is now up to something just as unusual among the great whites that have been observed so far – roaming around the sub-Antarctic Auckland Islands.
If she takes off to Australia again, Pip will become the first great white the team has tracked making more than one migration there using a special Spot tag attached to her dorsal fin.
The tag, which regularly transmits accurate fixes to a satellite, has allowed researchers to plot in detail her path across thousands of kilometres of open ocean since it was attached at Stewart Island in March last year.
The data could prove critical in solving some of the most enduring mysteries around the species, which are fully protected in New Zealand waters and globally considered a threatened species.
It is suspected Pip’s unusual trip to the Auckland Islands is because of food – namely New Zealand sea lions or Southern right whales.
“The information we have on the Auckland Islands is pretty limited, but there are quite a few observations of badly bitten sea lions,” Dr Francis said.
“So it’s almost certain they are feeding on them, but we don’t know about the whales.”
It remained unclear whether the windswept islands had their own population of great whites, or whether they were visiting from Stewart Island, a global hot spot for the predators.
But perhaps the more interesting question was whether Pip would later end up at the same spot off the Queensland coast where she was located in November.
“We know they are able to find their way back to Stewart Island each year, but so far we’ve only been able to track two sharks to the same place overseas, and that was done with a less accurate type of tag,” Dr Francis said.
“The more accurate Spot tag on Pip will tell us not only if she visits the same place, but also whether the route she takes is the same.”
Why she went to Queensland was another open question and, as with the Auckland Islands, a probable reason was prey.
“One of my colleagues is working on a stable isotope analysis that will give some idea about what they’ve been feeding on, but we are still waiting on some results for that.”
While there was still much to learn about great whites, Dr Francis said our understanding had grown immensely in the last decade.
“When we started our tagging programme in 2005 at the Chatham Islands, we thought we had a New Zealand-based population, or a possible New Zealand-Australia population, but we had no idea they went to the tropics – that was a total eye opener,” he said.
His team would keep tracking Pip until she eventually freed herself of her tag.
“It’s fascinating just watching and wondering what we are going to see next.”