Scientists are “hearing” on whales in the Arctic using fiber-optic cables. In July, a group of scientists published a study that took a practical method commonly used to monitor cables and used it to monitor the activity of baleen whales in the Arctic. Researchers say similar studies could change how scientists collect data on marine life.
Under the oceans, fiber-optic cables carry Internet traffic around the world. They have also become a common tool for scientists in the field who want to collect and access data in real time. In particular, they can be used to detect earthquakes, including aftershocks that are not detected by conventional seismic stations. In this case, those cables were used to detect the sounds of the whales. This is the first example of wildlife monitoring through a technique called distributed acoustic sensing, the study notes.
,[With] With distributed acoustic sensing, we can potentially get better coverage,” Leia Bouffot, who co-authored the study as a student at the Norwegian University of Science and Technology, explained ledge, “This could open up new possibilities in places that were either too complex to access or in areas where governments are willing to fund new projects like this,” said Bouffaut, a researcher at Cornell University’s K Lisa Yang Center for Conservation Bioacoustics. are not able to.”
Fiber-optic cables traverse vast areas of ocean floor
Whale researchers such as Bouffot commonly use hydrophones to monitor whale activity under water. Although Hydrophone provides good quality data, it can only cover so much ground. Boufft explained that hydrophones are typically positioned about 10 to 20 kilometers from each other. This relatively close proximity gives scientists a good idea of where the whale may have been located, a method similar to using cellphone tower triangulation where a phone call was made. But the oceans are vast, and even a large network of hydrophones can only observe a small area. Fiber-optic cables, in contrast, traverse vast areas of the ocean floor.
Distributed acoustic sensing is already used to check the health of undersea cables and can alert communications companies to problems such as line breaks. 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 functional, Boufaut explains. The interrogator sends light pulses over the fiber-optic cable at regular intervals. Sound or vibration can disrupt the cable and the pulses passing through it. By observing changes in the light reaching the interrogator, researchers can determine what is happening near the cable, whether the anchor is dropped near the cable or the whale is singing nearby.
Here is the sound of a whale caught by a virtual hydrophone.
Here is the sound of a whale caught by a virtual hydrophone. (opens a new window)
Boufft calls the result a “virtual hydrophone”. During the experiment, the researchers placed these “virtual hydrophones” at a distance of about four meters. The received data can be interpreted audibly, but it can also be visualized.
Similar to how fiber-optic cables pick up on vibrations from earthquakes, cables can pick up sounds via seismic vibrations that bounce off the fins of male whales. Yes, Finn. Apparently, according to the study, male whale fins can “make fin whale songs through a series of repeated short and low-frequency pulses that share similarities with airgun explosions”.
More data on baleen whales in particular could help fill in major gaps in our understanding of whale species, particularly in the warming Arctic where this research took place. Even though they are some of the largest animals on the planet, researchers don’t have enough information about some species of whales that they are threatened or endangered.
“We need to have scientific proof 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. ledge, Using fiber-optic cables, researchers can tell when whales are hitting boats, getting stuck in fishing gear, migrating in a different direction, and, as noted above, whether they are present in a specific area. The information collected is also essential for whale watchers as they recover and tackle a commercial whaling industry.
Now that the researchers have gathered the data for their study, Bouffot is exploring other uses for the recording technology. Some of the curiosities that Bouffot wants to take into account are whether they can only record at low frequencies, how many different species can be recorded, and how far researchers can record whales.
“One of my hopes is that we can exploit the idea that because we can get to the data in real time, we can deal with the data in real time,” Bouffaut said. “This is something that I believe can be helpful to the bioacoustic community because there are so many conservation issues that require real-time monitoring.”
