By Sandi Doughton

Seattle Times science reporter

Researchers who study climate change get their data any way they can: from weather balloons and satellites to deep-sea submersibles and ice-drilling rigs.

Now, a University of Washington biologist has devised one of the strangest methods yet: attaching instruments to the backs of narwhals.

Best known for their unicorn-like tusks, these marine mammals thrive in ice-choked seas where humans can rarely venture, said Kristin Laidre, of the Polar Science Center at the UW's Applied Physics Laboratory.

Laidre and her colleagues have tagged three of the whales with satellite transmitters that not only track the animals' movements but also measure water temperatures in a region of the globe where rapid warming seems to be under way.

"We've converted these animals into oceanographers," she said Wednesday by phone from Greenland.

The whales, which dive up to one mile deep to feed on bottom fish, already have provided the first winter temperature measurements in Baffin Bay between Canada and Greenland.

The region is part of the global "conveyor belt" of currents that brings warmer waters north, moderating the weather in northern Europe. An international science panel recently predicted global warming will slow those currents.

"Any weakening of the Gulf Stream because of climate change will immediately show up in this area," said Laidre's collaborator, Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources.

Global climate models have basically been "faking it" when it comes to the ocean west of Greenland, said Michael Steele, a senior oceanographer at the Polar Science Center.

"There's just a huge data hole in this part of the world ocean in the winter," he said.

After expanding for several years, the sea ice west of Greenland is declining rapidly. When the scientists flew over central Baffin Bay earlier this month, they found nothing but open water.

"This is a very sensitive region in terms of climate change," said Andrew Weaver, a climate expert at the University of Victoria in British Columbia who is not involved in the narwhal project.

"Using narwhals to get measurements is a totally fascinating approach," he said.

Long the subject of myth and misrepresentation, narwhals seem an unlikely animal to recruit for data-gathering, because they are so difficult to study. Not only do they inhabit the world's iciest oceans, they're also skittish and tough to trap, Laidre said.

Medieval traders passed narwhal tusks off as unicorn horns, which were believed to possess magical powers. Queen Elizabeth I of England reportedly laid out enough money to build a castle to acquire one of the spiraled tusks.

To trap the beasts, which weigh a ton or more, the scientists string long nets perpendicular to shore. They then mount a 24-hour watch, waiting for a narwhal (pronounced NAR-wall) to swim into the nets.

"You can sit for many weeks with your net in the water and never see them," Laidre said.

When a narwhal does get entangled, it fights furiously until the scientists wrestle it into a kind of hammock strung between two inflatable boats. Then they clip the transmitter, smaller than a deck of cards, to the animal's small dorsal fin.

The three narwhals the scientists are tracking now were trapped last summer.

During the second phase of the project, which just ended, the researchers used a helicopter to venture into the whales' icy wintering grounds. While the biologists scouted for narwhals, physicist Wendy Ermold from the Polar Science Center looked for thin ice where she could chip holes and lower a portable oceanographic instrument.

The instrument picks up more detail than the narwhal-mounted sensors, including water salinity. But the more conventional tool only provides a snapshot in time, while each narwhal transmits more than 400 temperature and depth measurements daily.

The narwhal project is funded by the National Oceanic and Atmospheric Administration's Office of Ocean Exploration and the Greenland Institute of Natural Resources.

In addition to oceanographic data, the studies are adding new insight to the narwhal's life, like Laidre's observation that the whales create what look like mole hills by pushing through thin ice to create breathing holes.

But the project didn't address the question that has long vexed narwhal-watchers: What is the purpose of the tusk (actually an elongated tooth)?

Researchers who recently found millions of nerve channels on the tusk surface concluded that it must be a sensory organ, used by males to detect changes in temperature or air pressure.

Laidre and Heide-Jørgensen scoff at that idea.

Females lack tusks, yet live longer on average than males, they point out. So the tusk can't be critical for survival.

Watching males gently cross tusks has convinced the scientists that the lance-like appendages provide narwhals a peaceful way to establish social stature.

"It's like a ballet," Laidre said. "They very gently and slowly interact."

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Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com

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