‘It really blew our minds’: rare whale insight gained
WELLINGTON: A new study tracking the movement of the world’s largest mammal has found a special New Zealand connection.
By using hydrophones,researchers from the University of Auckland and Niwa pooled international resources to understand how Antarctic blue whales move around the Pacific Ocean.
One of the researchers tracking the whales was Associate Prof Rochelle Constantine.
She said the researchers laid hydrophones throughout central New Zealand, including in Cook Strait, to record all sounds in the spaces.
‘‘Within the study, we collected data on all different kinds of whales, but this particular study focused on the blue whales that pass through New Zealand waters.’’
The hydrophones were deployed for about six months each, with the hope of capturing pygmy blue whales and Antarctic blue whales.
‘‘It really blew our mind what we found.’’
New Zealand was a great migration path for whales because it was a long and slim country, Prof Constantine said.
Until commercial whaling decimated their numbers, blue whales had been regularly sited in New Zealand waters, she said.
‘‘It’s exciting to get a handle on how they’re coming back, migrating through our waters.’’
There had been comprehensive studies on the pygmy blue whale, but the Antarctic blue whale, the largest whale on Earth, was much more elusive.
‘‘They’re more of an enigma, we virtually never see them. But, in this study, we hear them. We mainly hear them during the winter months when they’re migrating north — heading from their Antarctic feeding grounds up to breeding grounds unknown in the tropics.’’
The researchers suspected the Antarctic blue whales bred somewhere in the waters off Tonga and Samoa.
‘‘Then we hear them again later in spring as they’re swimming south again back down to feed in the Antarctic.’’
Prof Constantine said Antarctic blue whales, which were one of the most critically endangered whales, seldom came near shore and were rarely spotted.
‘‘We rely quite heavily on whale watch companies and oil and gas explorations telling us what they see. So, we rarely ever see them, but here they are in our waters. It’s an exciting thing.’’
Antarctic blue whales were hunted so severely their numbers dropped to less than 1% of their former population.
‘‘Today, after 55 years of protection, our estimate is that they’ve recovered to about 3% of their preexploitation numbers. The estimate is around 10,000 whales in the whole of the Southern Ocean.’’
The researchers found the whales moved up the east coast of New Zealand through Taranaki, where there is a lot of oil and gas exploration. While there had already been talk of protecting the pygmy whales in the area, Prof Constantine says there was now the most critically endangered whale to worry about.
‘‘I think there’s a role for New Zealand to play in ocean protection. There’s nothing more magnificent than watching an Antarctic blue whale, it’s like watching an island swim through the water.’’
❛ So we rarely ever see them, but here they are in our waters. It’s an exciting thing