Scientists Enlist Nature's Divers to Sample Icy Sea
Monday, April 16, 2007
For years, scientists have been trying to get a sense of the ocean north of Greenland but have been deterred by the harsh weather there. Now they have finally found deep-diving oceanographers willing to do their work for them: narwhals.
Narwhals -- whales that got their name because the Norse thought their skin resembled that of a drowned sailor -- used to be coveted for their 9-foot spiral tusks. In the 1500s, Queen Elizabeth I of England bought a narwhal tusk for a price supposedly equal to a castle, and other royals sought the tusk for medicinal purposes.
But researchers from the United States and Greenland are using them to analyze a part of the ocean crucial for regulating climate. The narwhals' wintering territory is near the northern Labrador Sea, where warm, salty water is moving north and cold, fresh water is moving south.
The mixing of these elements is of particular interest because it helps regulate the weather in northern Europe. Although scientists have measured ocean temperatures during the region's two warmest months of the year, no one has gauged the water during the winter.
"That's just a huge data hole there," said Michael Steele, a senior oceanographer at the University of Washington Applied Physics Laboratory's Polar Science Center.
The two lead scientists -- Kristin Laidre at the Polar Science Center and Mads Peter Heide-Jorgensen at the Greenland Institute of Natural Resources -- hope to attach satellite tags to as many as 10 narwhals over the course of a year. The tags have time, depth and temperature recorders that will allow researchers to track whale movements and diving behavior and ocean temperatures in Baffin Bay. Narwhals dive more than a mile below the ocean's surface.
"They basically collect data all the way down on their dive profile, and on the way back," Laidre said last month before she left for Greenland. "Nobody has done any research on narwhals out there, and this will be really interesting."
Laidre and Heide-Jorgensen completed the first part of their expedition last summer, when they tagged three whales along the coast of Greenland's Melville Bay. Late last month, they traveled to Baffin Bay for the more arduous part of the experiment, which involves venturing out onto sea ice to collect samples from narwhals hundreds of miles offshore. Another scientist from the University of Washington, along with an Inuit hunter from North Greenland and a filmmaker who is producing an educational film on the topic, joined them out on the pack ice.
Tagging narwhals -- even in the summer-- poses a challenge for researchers. "You can't drive a boat up to a narwhal -- they would never let you," Laidre said. "You kind of need to sneak up on them."
When a narwhal comes close, the scientists -- who wear bright-orange "survival suits" for protection if they fall into icy water -- wrap the whale in a net laid out for it. The net is suspended by small floats. When the narwhal gets caught in it, researchers drive out in inflatable boats to pull the whale to the surface and restrain it in what resembles a giant hammock. Often the whale starts "bucking around like it's in a rodeo," Laidre said, but it calms down once it gets a few breaths.
The researchers then attach the satellite tag to the narwhals' dorsal ridge and release it. The entire process takes about 45 minutes. "It's a very rapid-action moment," Laidre added.
Despite the chilliness this time of year -- it's about 25 degrees below zero with the wind chill-- the researchers have seen bowhead whales, polar bears and bearded seals in the region since arriving on March 29.