Narwhals “see” with sound better than any other species: study

An aerial view of a narwhal in open water. New research finds narwhals may have the most directional sonar signal of any species. (PHOTO BY KRISTIN LAIDRE)

Scientists have long known that the narwhal navigates through its environment with sound, but a recent study shows just how well the Arctic whale does it.

Research published Nov. 9 in the online scientific journal PLOS ONE argues that narwhals have the most directional sonar signal of any species, which helps the whales eke out a living in the often ice-packed waters of the Arctic.

Because narwhals live year-round in Arctic regions—largely Baffin Bay, Davis Strait and western Greenland—the whales live a more secretive life than many other animals.

But researchers have determined that narwhals, like bats and other toothed whales, use echolocation, that is, emitting sound waves to determine their surroundings and to find breathing holes in ice-choked Arctic waters.

They do that by sending out clicks of sounds that bounce off objects.

The clicks are inaudible to the human ear, but can be picked up by hydrophones —underwater microphones —which researchers from BioAcoustics Network in Germany and the University of Washington placed at sites in Baffin Bay and western Greenland in 2013.

Those clicks create a snapshot from sound, and narwhals use that data to create a larger acoustic image of their environment.

Narwhals appear to use highly directional signals, researchers say, focusing those clicks in a distant and forward direction to reduce “clutter” from the environment around them.

“The data collected in a most challenging environment show that the narwhal emits echolocation clicks with the most directional beam of all echolocators,” said Jens Koblitz of BioAcoustics Network.

Understanding how the narwhal’s sensitivity to sound could help predict future impacts as the Arctic environment changes, notably in regions such as Lancaster Sound, where the whales spend their summers, the study said.

That’s also the site of a proposed marine park and also a year-round shipping route for the Baffinland Iron Mine Corp. mine at Mary River.

The study cited other research which reported that narwhals demonstrated a “freeze response” to the presence of ice-breaking ships.

An upcoming Supreme Court appeal will argue against proposed seismic blasting in Baffin Bay and Davis Strait which Inuit groups say could have a major impact on marine mammals, particularly narwhals.

Research continues to consider the purpose of the narwhals’ spiraled tusk, the ivory tooth that grows from the left side of the male’s jaw and through the lip.

Some research has suggested the tusk is used as a sensory device.

But Kristin Laidre, an ecologist at the University of Washington, has found that males and tuskless females appear to be equally-skilled as echolocators, speculating the tusk is simply a sexual display.