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Why Scientists Are Firing Air Guns at Narwhals

Growing evidence indicates that underwater air guns used to detect oil and gas deposits affect the behavior of marine mammals. Arctic biologist Eva Garde talks about her research into the impact of air guns on elusive narwhals

Written by Ian Evans Published on Read time Approx. 5 minutes
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Narwhals can be especially sensitive to humans and human noise. Photo by Kristin Laidre/NOAA

Every summer, as Arctic sea ice melts, narwhals swim into Greenland’s Scoresby Sound to feed and breed. Known as unicorns of the sea for the long tusk-like tooth that spirals from their heads, they are notoriously shy around humans – and noise from companies searching for fossil fuels in the Arctic may threaten the migrating whales.

Fossil fuel companies fire underwater seismic air guns that send blasts of sound waves to the ocean floor. When the sound waves bounce back, they create images that can indicate the likely location of oil and natural gas deposits.

For wildlife, the sounds can be disruptive and even deadly. Many marine mammals, including narwhals, depend on sound to hunt and communicate with each other. Evidence suggests that these seismic explorations can confuse the animals, drive them away from migratory routes and even rupture their eardrums.

Yet to date there has been little research on air guns’ impact on marine mammals. Whales can be difficult to study, and elusive species like narwhals doubly so. So four years ago, a group of researchers at the Greenland Institute of Natural Resources (GINR) got together to figure out how they could study the nation’s endangered narwhals. The result was a series of projects that took place this summer to study the narwhals of Scoresby Sound.

Eva Garde, an Arctic biologist at GINR, traveled aboard the Pamiut, a research vessel equipped with small air guns. By firing these relatively quieter guns, Garde and other researchers were able to observe how narwhals reacted, and predict how the animals might be impacted by oil and gas exploration.

Oceans Deeply spoke with Garde about narwhals, how they use sound and what Garde was able to learn from the preliminary results of the research.

Eva Garde on board the Pamiut (courtesy of Eva Garde)

Oceans Deeply: I think that many people are familiar with how other marine mammals use sound – humpback whales and dolphins, for example. Why are narwhals so sensitive to sound, what do they use sound for?

Eva Garde: Narwhals use sound for navigating and communicating and hunting prey. Many [toothed whales] use echolocation to navigate in their surroundings. To be able to hear each other in the ocean is crucial for whales and narwhals.

They have been hunted extensively in Greenland, so they’re sensitive to human noise – anthropogenic noise. Another reason could also be that narwhals are occasionally hunted by killer whales. They are naturally more alert than perhaps some of the bigger whales that have no natural enemies once they reach adulthood.

Actually, there is a lot of noise in their environment. Out at sea or in fjords the ice is making a lot of sound. When the ice is slipping around or cracking, it sounds like gunshots and you can also hear the glaciers. So, there must be noise in their environment, but not as extensively as when you come with a seismic ship and shoot for days in a row with a seismic air gun.

Oceans Deeply: Can you tell me a bit more about these seismic air guns and your use of them?

Garde: The seismic equipment that we had with us was at least one-tenth of what the commercial operations are using for their seismic investigations. We didn’t want to use big air guns that create a lot of noise in this fairly closed [fjord].

We wanted to test the short-term effects of seismic testing on narwhals. When are they responding to the ship? We could test this because three narwhals had previously been tagged, so we knew where these narwhals were at all times, with a small time delay.

We could see where the narwhals were and see their reactions when we start the air gun. Now with the analysis that we will do, we will see the speed of the narwhals, the distance of the ship from them, if they stopped some behaviors that they were doing when they hear the ship – maybe they were feeding or migrating. We can see if they change directions. All sorts of things that we can now begin to analyze.

Oceans Deeply: So when ships with air guns do come through, you’ll know what the impact will be?

Garde: Yeah, then we can say, “Is there any short-term effect on narwhals when the commercial ships are there?” If a commercial ship is doing a seismic survey in an area where narwhals, for instance, feed or have their calf or something like that, then it is kind of vital behavior that we need to protect in some way. If we can see during this experiment that the seismic survey is indeed changing the behaviors of narwhals, then of course we need to make some kind of restrictions or some kind of management to protect narwhals during, maybe, certain periods of time when we know that they have these behaviors that are crucial.

Also, they migrate in certain patterns each year. They are up north in the summer, and then when the ice is forming in the fall, then they [swim] south. In the spring, when the ice is breaking, the narwhals follow the ice as it retreats north in Greenland. This is a very rigid behavior – they have this southward and northward migration each year. But if, say, there is a seismic ship blocking their way on their migration route, you can imagine that maybe they stop their migration and wait in an area that will be covered in ice in the fall. That could be one of the scenarios that we don’t want to see.

The Pamiut traveling through the Scoresby Sound in Greenland. (Photo courtesy of Eva Garde)

Oceans Deeply: What were you able to tell about the narwhals’ behavior from these seismic tests?

Garde: These are very preliminary results, and only what I saw from the vessel itself. Five times, we had the air gun on, and then we stopped for a period, and then we turned it on again. At least in the beginning, they were really fleeing the vessel – it seemed like. It was not real-time data – [the narwhals] were always at least 40 minutes ahead of [what we saw]. So, from the ship it could be difficult to really interpret data. But it seemed like they [fled from] the ship.

And then, maybe there was some habituation to the ship at the end of our trip. Or maybe it was because they were tired – I don’t know, and these are really preliminary results and we need to go further into the data.

Oceans Deeply: You say that you were unable to get real-time data, but you were using drones to try to spot them, right?

Garde: We used the drone for live pictures of the equipment and the seismic area. Sure, it would have been nice to be so close to the narwhals that we could actually get narwhal behavior on the drone, but that was not possible. Maybe for future operations we can get some nice drone footage of narwhal behavior, which is kind of rare at the moment.

There are places in Greenland where, you know that they’re there, you can see them from a distance if you stand on land. With a drone, you have the possibility to fly up to them and follow them. If we used drones for footage of narwhal calf/mother interactions, social behaviors within groups of narwhals or even (if we were so lucky) to observe mating behavior, we would learn so much more of these amazing animals.

A compilation video of the Pamiut’s trip, set to an ironic song.

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