Last updated June 14, 2018 at 2:08 pm
Scientists record the sounds of the Arctic’s ‘unicorn whale’.
US and Danish scientists have gone right to the source in a bid to start monitoring how human activity affects one of the Arctic’s most mysterious creatures – the narwhal or “unicorn whale” with the large protruding tusk.
They captured 533 hours of audio recordings that revealed three distinct types of sound – clicks, buzzes and calls – used in specific ways.
Clicks and buzzes were produced during echolocation for feeding, with calls more likely being for communication. Calls were typically produced at depths of less than 100 metres, with more than half being produced less than 7 metres from the surface. Buzzes were produced at 350-650 metres.
The researchers even identified a likely preferred feeding area: a particular fjord which had especially high buzzing rates. They also noted a possible stress response to capture and tagging; the narwhals were silent afterwards for around a day, reinforcing the need to record over larger timespans.
The team, which was led by Susanna Blackwell from Greeneridge Sciences in the US, captured six narwhals in East Greenland and tagged them with acoustic and satellite instruments.
Previous studies have mostly relied on underwater microphones, which are limited in their ability to record spatial and temporal variations.
As such, little is known about the narwhal’s acoustic behaviour or its reactions to anthropogenic sounds. The researchers hope their recent work will provide new insights into where and when narwhals produce sound and establish a baseline to help assess future impacts of climate and anthropogenic changes.
“Wide-scale changes are taking place in the Arctic, with warmer temperatures leading to shrinking summer ice coverage,” Blackwell said. “More ice-free water means easier access for vessels and industrial operations, such as exploration for oil and gas.
“The inhospitable pack-ice environment that is narwhals’ home for much of the year has for millennia kept them in relative isolation, even from biologists. Now new amazing tools allow us to take a multi-day, virtual ride on the back of a narwhal.”
The paper published in PLOS ONE. You can hear the sounds of the narwahl through the link here.