Non-invasive monitoring equipment is incredibly important for underwater scientific discovery. Placed in hard-to-observe areas, these devices silently and discreetly record sounds to help scientists understand and protect marine life.
Narwhals—the elusive Arctic whales with unicorn tusks—may not be as oblivious to these monitoring devices as researchers previously thought. In a new study published in Communication biologyScientists have recorded hundreds of narwhal interactions with underwater monitoring devices, showing that acoustic recording may not be as contactless as it seems.
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Curious narwhals love underwater exploration gear
Underwater microphones or hydrophonesused in the study are designed to listen quietly and not interfere with surrounding marine life.
“Using passive acoustic monitoring to detect acoustically active animals helps conduct biodiversity inventories, understand animal behavior and habitat use, and reduce the negative impacts of anthropogenic noise,” explained Evgeniy A. Podolsky of the Arctic Research Center at Hokkaido University in his paper. press release.
Although hydrophones must remain undetected, local NaryWals there were other plans.
During a two-year study in the Inglefield-Bredning fjord in northwestern Greenland, researchers working with local Inuguit hunters installed three hydrophones at depths ranging from 623 to 1,312 feet (190 to 400 meters). They were able to capture not only the beauty of Arctic soundscapes, but also the distinct “thumping” and “humming” of narwhals as they repeatedly explored the equipment.
In more than 4,000 hours of audio, the team counted 247 instances of narwhals striking devices. Given the gaps in recording time, the researchers estimated that there could have been as many as 600 hits, with an average of 10 to 11 per day, and usually during daylight hours.
Why are scientists interested in narwhals?
NaryWals are known for their long spiral tusks and are one of the most mysterious marine mammals on Earth. Living year-round in the icy waters of the Arctic, they use echolocation to navigate and hunt in the dark.
Although they remain a scientific mystery, the Inuguit hunters who helped deploy and retrieve the hydrophones used in the study are well acquainted with the curious nature of these whales.
“The Inuguit hunters were not surprised by the observed interaction: they are familiar with narwhal entanglement in unattended gear,” Podolsky said. “They also believe that narwhals love to play, and their parents tell them so, and they joke that narwhals can scratch their backs like cats.”
To understand why the whales were so attracted to these devices, the researchers also analyzed the stomach contents of 16 narwhals caught in the community fishery. They found a diet rich in cod, shrimp and squid. The team suspects that the narwhals may have mistaken the listening devices for prey, although it is also possible that they were simply too curious.
Why the narwhal's curiosity is important for Arctic research
For scientists studying life under ice, passive acoustic monitoring is a critical tool. These microphones can record for months, offering insight into animal communication, migration and the soundscape of a rapidly changing Arctic ecosystem.
But if the animals being studied are drawn to the instruments, this complicates the idea that this research method is truly non-intrusive. The results suggest that scientific infrastructure can subtly influence animal behavior, even when it is designed for quiet observation.
“Understanding the interactions of animals with industrial and scientific infrastructure can help reduce impacts on wildlife and improve our ability to conduct and interpret autonomous field observations,” Podolsky concluded.
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