A new study published on June 27 in Marine Ecology Progress Series shows that, for the first time, a small population of southern right whales is finding its way back to the ancestral calving grounds of mainland New Zealand.
More than a century ago, these whales were hunted to local extinction–so thoroughly that they didn’t remember their original calving grounds. This population, located around remote, sub-Antarctic islands is the first group to venture back home, according to the new study by researchers from Oregon State University, the University of Auckland and other institutions.
Before 19th century whaling, an estimated 30,000 of these whales migrated every winter to New Zealand’s well-protected bays to raise their calves.
“We used DNA profiling to confirm that seven whales are now migrating between the sub-Antarctic islands and mainland New Zealand,” said Scott Baker, associate director of the Marine Mammal Institute at OSU who initiated a study of these whales in 1995.
“These are probably just the first pioneers,” Baker said. “The protected bays of New Zealand are excellent breeding grounds, and I suspect that we may soon see a pulse of new whales following the pioneers, to colonize their former habitat.”
Southern right whales are particularly playful and tend to swim close to shore. This behavior has allowed them to become a popular tourist attraction in South Africa and Argentina, according to Baker.
Adult southern right whales can grow up to 50-60 feet long and weigh over 60 tons. Right whales earned their name from whalers because they are the “right” whale to kill. They swim slowly and close to the surface so they were easliy hunted by small boats. In addition, they float when killed because of their large stores of blubber.
In New Zealand and Australia, hunting peaked in the 1830s and 40s and none were seen around mainland New Zealand for entire decades of the 20th century. Right whales have a strong “maternal fidelity” which means that calving grounds and migration routes are passed from mother to calf.
The researchers explain that “fidelity to calving grounds can be viewed as a type of cultural memory, and it seems the memory of the suitable calving ground can be lost along with the whales that formerly inhabited such areas.”
“This maternal fidelity contributed to the vulnerability of these local populations, which were quickly hunted to extinction using only open boats and hand-held harpoons,” said Emma Carroll, lead author on the study and a doctoral student working with Baker.
In just the past few years, some right whales are returning home. In 2005 there were fewer than a dozen reproductive females near the mainland and today there are only a few dozen more. Of these few, many are coming from the sub-Antarctic islands and hopefully more will follow.
“The right whale is remarkably graceful, very spectacular to watch,” Baker said. “There used to be thousands of them in New Zealand and they are now re-discovering their ancestral home. It will be interesting to see what develops.”
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC