What Happened When Scientists Dropped a Hydrophone into an Arctic Fjord

追加: 2026-05-05

[00:00:00]Scientists dropped a series of microphones to the Arctic seabed to listen in on the animals that live there. And then the unicorns appeared.

[00:00:08]Welcome back to Tea of the Sea. And if we want to get an idea of what our oceans are like and how the animals that inhabit them are living their daily lives, it's very difficult to directly observe their behaviors without impacting the animals we're observing in some way. Most of the time, the act of us observing wildlife, especially in the oceans, can cause a degree of disturbance. Either we are there diving alongside the animals or the noise that we make getting to the animals by our boats and whatnot can disrupt their overall behavior. More recently, some studies have been coming out with a lot of information gained from acoustical monitoring, which is the act of just dropping a microphone down to the seabed and just listening in on the ocean conversation. Through acoustical monitoring, we can listen in on conversations and learn how animals are communicating to each other uh as a species, as a group, as an individual.

[00:01:06]But we can also gain information through sounds about where animals are congregating in and where they're moving to and from if they're more migratory in nature like whales are. Alongside all that, acoustical monitoring can help us better understand how our activities are affecting ocean ecosystems through the noise that we produce and what we can do to reduce that impact overall. And this is what a team of researchers from Japan set out to do when they went into the Breading Fjord in Greenland and dropped several hydrophones between depths of 190 and 400 m below the surface.

[00:01:40]Throughout this 2-year study, though, the scientists recorded something a lot more interesting than just the overall noise of the fjord and the animals that live in it. They also recorded sounds of a unique behavior being produced by the unicorns of the north, the narwhal.

[00:01:57]Narwhals are a small species of citation and are one of three species that are endemic to the Arctic alongside the beluga whale and the boowhead whale. And of course, they're called the unicorns of the north because they are the whales that have the 3 m long tusk that protrudes out of the upper jaw of most males and some females. Historically, we don't know a whole lot about narwhal behavior compared to other citations because of a couple things. First and foremost, they live in the Arctic. They live in cold, remote areas that are really difficult to get to. And two, they're actually pretty shy. They're not very friendly whales when it comes to human interaction. They generally keep to themselves. So, it came as a surprise to the scientists of this 2-year Arctic acoustical study where they found that they had recorded 247 incidents of the local narwhals of the breadning fjord actually approaching the hydrophone and bumping the devices and rubbing up alongside them. During these incidents, the narwhals, like I said, were bumping the hydrophones. They were rubbing against them. They were bashing them.

[00:03:04]And as they approached the hydrophones, they were making echolocation clicks as well as a buzzing noise that is associated with narwhal foraging habits.

[00:03:14]The scientists believe that the reason for this behavior is one of two things, at least in terms of how it started.

[00:03:23]First and foremost, they think the narwhals were overall curious about this strange device that was in their normal feeding areas. But they also think that the narwhals may have been actually confusing the hydrophones with the fish like cod that the whales are known to feed on. But that second idea was actually kind of thrown to the side because of the behavior that the hydrophones were recording. They were recording the whales approaching the hydrophone making that buzzing noise associated with foraging. And then afterwards they were actually rubbing up alongside the hydrophones indicating that the whales probably knew that those hydrophones were not actually fish. at least later on in the recorded incidents that they have. Maybe the whales had an itch and they were just using the hydrophone as an opportune scratching post. Other whale species like orcas are known to actually scratch themselves along rocks. And some other species like boheads will scratch along ice to rid themselves of parasites and dead skin.

[00:04:17]But because of the depth of the hydrophones and the cost of energy that it takes to make those kind of deep dives, the scientists believe that that's not really what the narwhals were up to. Overall, it appears that those this behavior stems just from an overarching curiosity as narwhals in that area don't really observe a lot of man-made objects just sitting at the bottom of the seabed. So maybe they were just kind of curious and just kind of pressing up against the hydrophone just to get an idea of what it was. Maybe they were playing with it. We'll have to do more studies like this to really understand further. The coolest part about this study for me is that although they have 247 instances recorded of this rubbing behavior, because the hydrophones weren't recording 24/7 for 2 years, the scientists believe that there were hundreds more encounters like this that the hydrophones had with the narwhals. The scientists estimate that the whales had knocked those hydrophones anywhere between 10 to 12 times on a daily basis, indicating to me that maybe they were just playing with this new interesting thing in their water. For now though, the reasoning behind this behavior from these narwhals is kind of left up in the air. For me, it seems as though they were just kind of playing and we're just overall curious about the hydrophones. And more studies like this will need to be done in the future for us to better understand how the unicorns of the sea go about their day and what they do to entertain themselves as they're moving around their cold water world.