The beluga also have a strange habit of dining in single-sex restaurants. Tiny tracking devices developed by British scientists are helping to shed light on the extraordinary and hitherto unknown roamings of this small, pure white whale.
Dr Tony Martin, of the Sea Mammal Research Unit at St Andrews University, told the British Association's annual Festival of Science in Leeds that the new technology had transformed their understanding of the fish-eating beluga.
It was thought to be a coastal, shallow-water species. It turns out that it can travel thousands of miles each year, dive to more than half a mile in depth and navigate long distances under ice, finding tiny, thinly scattered patches of unfrozen water where it must surface to breathe.
With his research partly funded by the Canadian government, Dr Martin is studying a group of belugas which migrates each year to the Mackenzie Delta on Canada's north coast, near the Alaskan border. There, they shed their skin over three weeks, scraping it off on the bottom before moving on.
Dr Martin's team has attached tracking devices to dozens of the whales. The devices continuously record the depth of the whales. Whenever the animal surfaces to breathe, the device, about the same size as a mobile phone, rapidly beams its record of time and depth up to a satellite in a burst of electronic data, simultaneously registering the exact location of the whale.
From such data he has found that the whales follow "invisible motorways" as they head to sea, all following the same track. Mature males, weighing up to two tons, were found to head north, seeking out "the deepest trench for hundreds of miles around".
There they dived repeatedly to a depth of 500m, spending many minutes at the bottom. Dr Martin believes they were feeding on polar cod. "There must be fantastic food resources there," he said.
Only males ever go to this single-sex restaurant. Females and the young head for shallower feeding grounds. He believes this is because they cannot dive for as long or to the same depth.
He also found another sort of dive, in which the males go as deep as 700m, then immediately return to the surface instead of spending time looking for food. Dr Martin believes they do this because it helps them locate air holes in the ice many miles away, probably using sound. "We found that, far from being coastal, they have access to the entire Artic ocean," he said.
As a result, he thinks their population may be more than twice as high as official estimates of 40,000 to 80,000. More than 2,000 are killed for food each year by native peoples living in the high Artic. Being small, they are not covered by the International Whaling Commission's moratorium on killing great whales.
Research by Professor Mike Fedak, another member of the Sea Mammal Research Unit, suggests that elephant seals living in the Antarctic appear to have some as yet unknown means of communication to tell each other where the best food sources are.
"Mothers dump their pups on the shoreline, leaving them with about one month's worth of fat to live off," said Prof Fedak. "They have to survive or die. In fact, about 50 per cent of pups die in their first year."
But those which survive seem to travel, alone, along the same routes and converge on the same feeding grounds. "They can navigate to places that they haven't been to before," such as tiny islands, Prof Fedak said.
"There is no evidence yet that they make loud calls. But nobody knows, down there.
Leading article, page 13
Commentators, page 15Reuse content