A Sentinel Species For Climate Change Decimated by whaling, the now recovering species faces a new threat, the changing ocean
Photo credit: Richard Robinson © 2021
The return of the tohorā/southern right whale is one of Aotearoa’s best conservation success stories. They were decimated by whalers in the 19th century, from estimates of 30,000 of these great whales to around only 40 left by 1920. They were called the ‘right’ whale to hunt because of their slow moving, curious and docile natures. An international hunting ban and a marine reserve located in the Maungahuka/Auckland Islands allowed the whales to recover, by 2009 there were approximately 2,000. The reserve provides a refuge and safe breeding/nursery ground for the whales during winter, vital to the success of their recovery. Scientists have counted between 150-200 of these gentle giants in a single day in the Auckland Islands, while the closely related population of north Atlantic right whales is in serious decline, with only 366 left in 2021.
The IMF estimates that each great whale sequesters 33 tons of CO2, on average, taking that carbon out of the atmosphere for centuries. They also help produce phytoplankton. Even a 1% increase in phytoplankton productivity thanks to whale activity would capture hundreds of millions of tons of additional CO2 a year, equivalent to the sudden appearance of 2 billion mature trees.
Very little is known about where these whales go once they leave the safety of their winter grounds and where they spend the other nine months of the year before returning home to the Maungahuka/Auckland Islands. Scientists need to find out where they’re going ahead of a major new challenge to their recovery, climate change. International trends are showing these whales are breeding less often and it’s thought they’re either getting less food or food is shifting from regions where they’ve traditionally visited. Without enough food, whales cannot breed or nurse their calf.
Over the course of three consecutive winters between 2020 and 2022, Associate Professor Emma Carroll from the University of Auckland and her research team put satellite trackers on 25 tohorā/southern right whales. Follow this year’s tracks as these playful giants migrate from Maungahuka/Auckland Islands to their chosen feeding grounds. The 2020 and 2021 tracking data astounded scientists, unexpectedly showing that the most of the whales travelled west under Australia, rather than to the east of New Zealand as whaling records indicated.
The research is now progressing to analysing 135 individual biopsies with pioneering genomics approaches and state of the art reading of micro-chemical markers that reveals where whales have been travelling through stable isotope analysis. This data will then be publicised to inform regulatory authorities and policy makers of the estimates of the New Zealand southern right whale population, their significance and the importance of keeping shipping away from their seasonal migratory routes.
Through our donors, Live Ocean Foundation provided pivotal funding for all three voyages to obtain this vital information.
The images on this page were taken on assignment by New Zealand Geographic photographer Richard Robinson at Port Ross in the subantarctic Auckland Islands. Coverage taken under New Zealand Department of Conservation permit.
This year we will be following the journeys of eight more of these amazing ocean voyagers as they head offshore to their summer feeding grounds.
As of August 2022, five of the whales tagged in July had started migrating south and west, and several, including two mums with calves, were still around the Auckland Islands.
Follow the journeys of these curious travellers here and for more information on the tohorā satellite tracking program, check out https://tohoravoyages.ac.nz/
TEKAU mĀ WHITU
Tagged on 7 July 2022 and started migrating south soon after.
TEKAU MĀ IWA
Tagged on 8 July 2022 and a few days later started migrating west from the Auckland Islands.
RUA TEKAU MĀ TAHI
Rua tekau mā tahi is the first female tohorā the research team have tagged. She was hanging out with other adult whales and her calf when she was tagged on 10 July 2022.
RUA TEKAU MĀ TORU
Rua tekau mā toru was hanging out alone when tagged on 11 July. He then spent two weeks around the Auckland Islands travelling down to Carnley Harbour from Port Ross.
Photo credit: Richard Robinson © 2021
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