Three underwater robots spent weeks listening to grey whales off the west coast of Vancouver Island last month, so scientists can learn more about what the whales are doing in northern waters.

The two-metre long yellow gliders travelled together in underwater canyons over the continental shelf near Clayoquot Sound.

"They're like torpedoes with little wings," said Richard Dewey, Associate Director of Science Services for Ocean Networks Canada.

"They're measuring sea water temperature, but they had some special sensors on them as well," Dewey explained to guest host Megan Thomas on All Points West.

"There was one configured with a hydrophone that was listening for whale calls and another one had an echosounder on it, specially tuned to look for krill and zooplankton, which is what the whales are feeding on."

Researchers used underwater gliders to learn more about why grey whales hang out off the west coast of Vancouver Island. (Craig Hayslip/Oregon State University Marine Mammal Institute)

Looking for whale hotspots

Glider pilots talked to the robots through satellites several times a day and gave them commands on where to go next.

Researchers are now using the data to figure out what the whales are encountering in our waters as they migrate up the coast from their winter habitat off California, to their rich feeding grounds in the Bering Sea off Alaska.

"Sometimes they pause and they hang around certain hotspots," said Dewey.

"Are they finding lots of food there? Do they take a break and socialize? The goal is to map out critical whale habitat and find why are the whales hanging out in some areas more than others."

Map of glider tracks off Clayoquot Sound. (Ocean Networks Canada)

Ships vs. whales?

A similar project took place on Canada's East Coast. Researchers there found that some whale habitats were crossing shipping lanes. They used the results to have the shipping lanes adjusted to minimize encounters between whales and ships. Dewey said that could be the case on the West Coast as well.

"As the ships come out of Juan de Fuca Strait, they head off on their transpacific shipping lanes," said Dewey. "They don't worry about where they're going as far as the marine habitat goes. But if we find there's some critical whale habitat for humpbacks or killer whales or the grey whales, then we might put a policy in place that would minimize ship whale interactions."

This is the first time three underwater robots have been used to map out whale habitat off the B.C. coast.

The gliders were provided by Ocean Networks Canada, the University of British Columbia and Dalhousie's Ocean Tracking Network. After several weeks underwater, all three gliders were successfully recovered on Feb. 18.