Whale-watching by satellite

Part of a major research project involving the University of Auckland and Cawthron Institute, the researchers worked in freezing conditions in the sub-Antarctic where tohorā gather each winter in the sheltered harbour of Port Ross on Auckland Island which serves as a nursery and socialising destination.

This gathering provided scientists with the opportunity to attach the tracking tags and do other research including taking skin samples for genetic and biochemical analysis and to measure the size of individual whales using drone technology.

This latest expedition to Port Ross, which lies more than 400km south of Stewart Island in the Southern Ocean, aimed to find out more about the migration routes and offshore feeding grounds of this population of whales.

Early results from the satellite tracking shows the whales already leaving Port Ross for the summer but so far they have defied predictions of where they might head to.

“We had expected they would travel north to the warmer waters nearer New Zealand and Australia where we assume their traditional feeding grounds are,” says lead researcher Dr Emma Carroll, a Royal Society of New Zealand Te Apārangi Rutherford Discovery Fellow at the University of Auckland.

“But so far they have swum even further south towards Antarctica so whether they will turn back to the north at some point we don’t yet know. They have also spent longer in the general region of the Islands than we thought they would, so that’s a clear indication of just how important this area is to these amazing animals.”

Dr Carroll said the expedition of eight scientists into the wild Southern Ocean aboard the yacht Evohe posed some major challenges.

“It was freezing cold with snow and sleet, so working in those conditions is really hard but we went prepared. Sailing into Port Ross and seeing so many whales was a wonderful moment.”

Cawthron Institute marine ecologist Dr Simon Childerhouse who was also involved in the expedition says this particular population of tohorā have recovered well from whaling from the early 1800s when numbers plummeted to as low as 40 from an estimated 30,000. By 2009, the population had recovered to around 2000 whales.

But one of the biggest potential remaining threats to tohorā is climate change and the effect it might be having on marine species the whales rely on for food once they reach summer feeding grounds.

"Other tohorā populations in the Southern Hemisphere are not faring that well and there is ongoing concern about how climate change may be affecting the amount of food available to them.

"We need to do more to whether these impacts have had the same effect on New Zealand's population to date, and learn from what has happened elsewhere so that we can protect New Zealand's tohora now and in the future."

The research is made possible by private equity leader, philanthropist and New Zealand proprietor Brian Sheth; the Royal Society of New Zealand Te Apārangi; the University of Auckland; Live Ocean and the Lou & Iris Fisher Charitable Trust.

You can follow the voyages of the whales and support the work at: www.tohoravoyages.ac.nz and www.liveocean.com