With the help of Inuit Eskimos, scientists have managed to get close to shy narwhals, to record their sounds under the waters of a Greenland fjord. This is how they have discovered the whistles they emit to communicate and the clicks with which they echolocate the fish, which they end up surrounding with a chainsaw buzz.
The elusive and mysterious narwhal (Monodon monoceros), sometimes called a sea unicorn because of the characteristic horn of the males, is a cetacean that spends most of its time in the depths of the Arctic Ocean. In summer it usually comes close to the coasts, but it is difficult to study because it is very scary.
Two researchers from the University of Hokkaido (Japan) participated in the stealth hunts organized by the Inuit with their kayaks to be able to record the sounds of these cetaceans in a remote fjord in northwestern Greenland, obtaining very valuable information to know the behavior of these shy and mysterious creatures.
Using underwater microphones attached to small boats, the scientists got within 25 meters of the narwhals and managed to capture both their social calls and the sounds they make to search for food: schools of fish.
The vocalizations to communicate with their peers resemble whistling. However, they use clicks for echolocation, that biological sonar that dolphins, bats, whales and other animals use to navigate and locate their prey.
The closer the narwhals get to their food, the faster they click, and there comes a point where the noise resembles that of a chainsaw, a final buzz that helps identify the location of the food. "If you approach and point to these fast fish, you better know precisely where they are, and for this you need to gather the information more often“Explains Evgeny Podolskiy, the principal investigator.
To listen and visualize how narwhals use their different sounds, the authors, in collaboration with the American Geophysical Union (AGU), have published a video on YouTube with the different scenarios.
“Many studies have characterized ocean noise in various parts of the world, including the Arctic, but in glacial fjords this is difficult and dangerous as you approach the glacial front, where large chunks of ice break apart and there may be tsunamis due to the collapse of ice. icebergs”Podolskiy explains.
“But nevertheless -go on- Just this environment serves as a summer home for animals as little known as narwhals. Knowing the soundscape that surrounds them will help us understand them better. Our work characterizes this environment and shows how noisy it is, due to the fractures of the ice and the bubbles that bubble under the water, something that the animals that live here do not seem to have many problems with.”.
“I realized that we were working in this area without paying attention to the 'elephant in the room' in front of us, the legendary Arctic unicorn moving around our glacier”Acknowledges the scientist, who realized his mistake and in July 2019 decided to join several expeditions of Inuit hunters who, with their ancestral knowledge and their harpoons, left the village of Qaanaaq in search of this and other marine animals .
“The locals know, see and hear the whales much better than any stranger, so going with them was a very fruitful collaboration to characterize the animal, environmental and anthropogenic sounds of the fjord”Says Podolskiy, who had previously considered other alternatives.
“We could have captured the records with moored instruments (rather than in kayaks or boats with the engine off), but we would have had little idea of what is going on, how many animals are there and where they are -the researcher points out-, and we could also have caught specimens to put tape recorders on, but this is very difficult and stresses them”.
Sustainable hunting of the Inuit
Regarding the hunting of narwhals by the Inuit, the scientist clarifies that it is controlled by official government licenses and quotas: “98 narwhals are allowed to be killed per year, an activity considered sustainable that affects 1 or 2% of this subpopulation, although the information on the abundance of these cetaceans is really poor and more studies are needed”.
The geophysicist also highlights that this research is motivated by the threat posed to fauna by the unprecedented changes suffered by the Arctic: “Disappearance of sea ice, retreat of glaciers with consequent discharge of sleet and sediment, arrival of predatory invasive species (such as killer whales) and anthropogenic activities such as marine traffic and seismic air guns, which seem to really stress narwhals”.
“However,” he concludes, “it is difficult to know how these factors affect when scientists are not even sure where these animals come from, when exactly they arrive and how many there are. We hope that its acoustic monitoring in a typical habitat is a first step that can be repeated in many other places to get to know the narwhals better ”.
Source: European Space Agency