TO A loud bang breaks the winter calm of Port Ross, in the remote Auckland Islands of New Zealand, and the small inflatable boat is tossed by the whirlpool of a 40-ton whale that is swallowed by the cold, dark water.
When it reappears, the team of scientists are happy to see its $ 3,200 satellite tag securely attached to its side. The whale, whom they have nicknamed “Bill”, glides into the ocean, the tag transmits its movements. A few days later, the researchers observe how it begins to head west, towards Australia.
Over a year later, they are still watching. The team, from the University of Auckland and the Cawthron Institute, satellite-tagged six whales in Port Ross in August 2020. They expected the tags to last for six months, the typical lifespan of these devices. Bill’s label, however, has continued to pass, giving scientists the first glimpse into a full year in the life of a right whale.
It has now recorded the longest southern right whale migration ever recorded, a journey that covers more than 15,000 km (9,300 miles) and crosses three of the world’s great oceans.
Southern right whales were nearly wiped out by 19th century whaling. In the 1980s, a remnant population was found breeding on the uninhabited Auckland Islands, 500 km south of New Zealand. Since then, their numbers, on the Auckland Islands and elsewhere in the southern hemisphere, have increased steadily.
At the time Bill was tagged, almost nothing was known about where New Zealand’s whales went outside of breeding season. The best information available, perversely, was the records of the old whaling ships, which showed frequent deaths in the waters north and east of New Zealand.
Therefore, lead scientist Emma Carroll was surprised when Bill and the other tracked whales headed in the opposite direction, towards Australia.
“It has changed the way we think about whale ecology,” he says. “It suggests that the northeastern feeding zone is not as heavily utilized as historically.”
Right whales feed on copepods and krill, tiny crustaceans that filter out of the water with their baleen mouths. After leaving the Auckland Islands, the tagged whales spent a month foraging for food in waters off southern western Australia. Four of the labels stopped broadcasting at this point.
Bill and another whale, Tahi, made their way into the Indian Ocean, almost halfway to Africa. Tahi turned and headed back toward New Zealand, while Bill headed south, swimming thousands of miles more in the krill-rich waters of the Southern Ocean. It then slowly headed east along the edge of the Antarctic ice.
In 1840, the explorer James Clark Ross witnessed large numbers of “black” whales in polar waters south of New Zealand. Their report is believed to have referred to southern right whales, but the species was never re-recorded there, perhaps because they had been heavily hunted in their breeding grounds.
Bill’s trip is the first modern evidence that New Zealand’s right whales are frequenting Antarctica once again.
By winter, Bill had returned to the Auckland Islands, having traveled a third of the way around the world.
The researchers hope that Bill’s tracks, and those of later tagged whales, will help identify food-rich areas in the poorly studied expanse of sea that whales visit. Once identified, these areas can be protected.
Elsewhere in the southern hemisphere, the recovery of populations on the southern right appears to have been hit by warming oceans. The whales in South Africa have been forced to change their foraging grounds and, as a result, their breeding success has declined.
New Zealand whales, by contrast, are among the fattest and healthiest on the planet. The key to your success may be the apparent adaptability of your eating strategies.
“Bill was feeding in two completely different regions of the ocean,” says Carroll. “It shows that if one feeding area is not very productive, the whales can move to other areas.”
“Hopefully these whales will be able to adapt to changes in the oceans,” he says, “but we must also give them a chance. These whales live 70 years, maybe longer. The amount of change over your lifetime will be incredible if we don’t slow down climate change. “
Carroll and his team returned to the Auckland Islands in July 2021, deploying satellite tags on 12 more whales. Most of them headed down a path similar to that of the whales of the previous year. Unbelievably, Bill’s label, at the time of writing, is still running. He’s heading west again, on another grand tour of the world’s southernmost oceans.
Bill’s journey and the voyages of other tagged whales this year can be followed at www.tohoravoyages.ac.nz
George is Digismak’s reported cum editor with 13 years of experience in Journalism