COURTESY ROBIN W. BAIRD
Adult male Blainville's beaked whale shown. Blainville's beaked whales regnularly dive to depths of 2,624 feetaccording to research published online in the Canadian Journal of Zoology today .
Obscure whale species like to dive deeper
Beaked whales can stay submerged 45-80 minutes at a time
Two of Hawaii's least-known whales are "extreme" divers that sometimes plummet to depths seven times deeper than the more familiar humpback whale, says the lead author of a new study.
Cuvier's and Blainville's beaked whales regularly dive to depths of 2,624 feet, and the Cuvier's species was recorded going to 4,757 feet, according to research published online today in the Canadian Journal of Zoology.
That compares with typical dives of 350-650 feet for humpback whales in Hawaii waters, said Robin Baird, of the Cascadia Research Collective in Olympia, Wash.
And the beaked whales stay underwater from 45 to 80 minutes at a time, Baird said. By comparison, pilot whales dive for about 27 minutes at a time, he said.
"For such a small whale, they are diving incredibly deep and staying down incredibly long," Baird said. "They are extreme divers, pushing their physiological limits."
Hawaii's beaked whale species are much harder to spot than humpbacks because they are much smaller (15 to 19 feet long) and do not have a high-spouting blowhole, Baird said.
One reason Baird wanted to study the Cuvier's and Blainville's beaked whales was because beaked whales have been most commonly associated with mass strandings linked to the use of high-intensity naval sonar, he said.
There are 21 species of beaked whales worldwide, but little is known about them, Baird said yesterday by cell phone from a boat following killer whales along the Washington coast.
After searching around all the major Hawaiian islands, Baird's group -- which includes Big Island researcher Dan McSweeney -- found its best chances of spotting the Cuvier's and Blainville's beaked whales was off the Big Island's Kona Coast.
When they could get close enough, the researchers attached depth-finder recorders to the whales with suction cups. The devices stayed on from a few hours to 64 hours, Baird said yesterday, providing the group with a second-by-second look at how deep the whales would go.
Though the researchers saw both species of whale with about the same frequency, they had much better luck approaching the Blainville's beaked whale, which accounted for 150 of the 160 hours of dive data collected over the five-year study period, Baird said.
A key finding of the research was that the beaked whales ascend from their deep dives at a slower rate than they descend, Baird said.
That could be a clue as to why beaked whales have been involved in strandings after sonar use, Baird said. The unfamiliar sounds could startle the animals into rising more rapidly than normally.
"This may be a mechanism to cope with gas bubble formation associated with such regular long and deep dives," Baird said in a release from the Cascadia Research Collective.