Scientists have been “eavesdropping” on whales in the Arctic using fiber-optic cables. In July, a group of scientists published a to study who took a practical method typically used to monitor cables and used it to monitor baleen whale activity in the Arctic. The researchers say similar studies could transform the way scientists collect data on marine life.
Under the oceans, fiber optic cables carry Internet traffic around the world. They have also become a popular tool for scientists in the field who want to collect and access data in real time. It should be noted that they can be used to detect earthquakesincluded replicas that go unnoticed by traditional seismic stations. In this case, those cables were used to detect whale sounds. It is the first instance of wildlife monitoring to be done through a technique called distributed acoustic sensing, the study notes.
“[With] distributed acoustic sensing, we can potentially have better coverage,” said Léa Bouffaut, co-author of the study as a student at the Norwegian University of Science and Technology. the edge. “This can open up new possibilities in places that were too difficult to access or in regions where governments can’t fund new projects like this,” said Bouffaut, now a research fellow at the University’s K. Lisa Yang Center for Conservation Bioacoustics. from Cornell.
Fiber optic cables traverse huge areas of the seabed
Whale researchers like Bouffaut typically use hydrophones to monitor whale activity underwater. Although the hydrophone provides good quality data, it can only cover part of the ground. Hydrophones are typically deployed between 10 and 20 kilometers away, Bouffaut explained. This relatively close proximity gives scientists a good idea of where the whales might be located, a method similar to using cell phone tower triangulation to detect the location of where a phone call was made. But the oceans are huge, and even a large network of hydrophones can only observe a small area. Fiber optic cables, by contrast, traverse large areas of the seabed.
Distributed Acoustic Detection is already used to check the status of undersea cables and can alert communications companies to problems, such as a line outage. It works because a fiber in the cable is connected to something called an interrogator, a device that measures whether a fiber-optic cable is working, Bouffaut explains. The interrogator sends pulses of light down the fiber optic cable at regular intervals. Sounds or vibrations can disrupt the cable and the pulses passing through it. By looking at changes in the light reaching the interrogator, the researchers can determine what’s happening near the cable, whether it’s an anchor dropped near a cable or a whale singing nearby.
Bouffaut calls the result “virtual hydrophones”. During the experiment, the researchers placed these “virtual hydrophones” about four meters apart. Received data can be interpreted audibly, but can also be displayed.
Similar to how fiber optic cables pick up vibrations from an earthquake, the cable can pick up sounds through seismic vibrations that bounce off the fins of male whales. Yes, fins. Apparently, male whale fins can make fin whale songs through a “series of repeated short, low-frequency pulses that share similarities with airgun blasts,” according to the study.
More data on baleen whales in particular could help fill major gaps in our understanding of whale species, especially in the warming Arctic where this research took place. Although they are some of the largest animals on the planet, researchers don’t have enough information on some whale species to know if they are threatened or endangered.
“We need to have scientific evidence of what they are doing and how they are doing it”
“We need to have scientific evidence of what they are doing and how they are doing it,” Bouffaut explained to the edge. Using fiber optic cables, researchers can tell when whales are being hit by ships, caught in fishing gear, have migrated in a different direction and, as mentioned above, whether they are present in a specific region. The information collected is also essential for monitoring the whales as they recover and cope with a commercial whaling industry.
Now that the researchers have collected the data for their study, Bouffaut is looking at other uses for the recording technology. Some curiosities that Bouffaut wants to consider are whether they can only record at low frequencies, how many different species can be recorded, and how far researchers can record a whale.
“One of my hopes is that we can exploit the idea that since we can receive the data in real time, we can handle the data in real time,” Bouffaut said. “This is something that I think can be useful for the bioacoustics community because there are a lot of conservation issues that require real-time monitoring.”