Madrid, 5 (European press)
So far, this type of study has been carried out combining satellite tracking, atmospheric studies, viewing operations and the deployment of individual hydrophones to listen for the calls of cetaceans.
The new technology, called Distributed Acoustic Sensing, or DAS, uses a tool called an interrogator to access a fiber-optic system, converting the extra, unused fibers in the cable into a long virtual array of hydrophones. The research was conducted in the archipelago of Svalbard, in an area called Isfjorden, where baleen whales, like blue whales, are known to feed during the summer.
“I think this could change the field of marine bioacoustics,” Leah Bofo, first author of a research paper just published in Frontiers in Marine Sciences, said in a statement. Boffo was a postdoctoral student at NTNU, the Norwegian University of Science and Technology, when she worked on this research and is now at the K.
The beauty of the new system, Buffo said, is that it can allow researchers to take advantage of an existing global network. “The installation of hydrophone systems is very expensive. But fiber-optic cables are scattered all over the world and are accessible,” he said. “This might be a lot like how satellite imaging coverage of the Earth has allowed scientists in many different fields to do many different kinds of studies of the Earth. For me, this system could become ocean satellites.”
Other types of sound-based whale watching often provide information only from one location or from a few points on a water pistol, Buffo said. Point locations provide limited coverage of an area and are of course not evenly distributed across oceans, which can make it difficult for researchers to study migration routes, for example.
In contrast, DAS not only allows researchers to detect whale sounds, but they can also use the fiber network to determine where whales are in both space and time, with unprecedented spatial accuracy.
“With this system, which is what we would essentially call a hydraulic array, we have the opportunity to cover a much larger area of observation. And because we receive sound from multiple angles, we can even tell where the animal is: the position of the animal. That is a huge advantage. And if we take it further than However, which still requires a little extra work, this could happen in real time, which would really be a game-changer for acoustic whale monitoring,” said Hannah Joy Kressel, one of the paper’s co-authors.
Martin Landru, a geophysicist at NTNU and one of the authors of the paper, said the technology also allows researchers to “hear” other water-borne sounds, from large tropical storms to earthquakes and passing ships. Landro is also the director of the Geophysical Prediction Center, a research-based innovation center funded by the Norwegian Research Council.
We discovered at least four or five different big storms that had occurred and were able to go back to the weather data and identify them by name.
“If something moves near those fibers buried in the sea floor or makes acoustic noise, we can measure that,” he said. “What we saw was a lot of ship movement, of course a lot of earthquakes, and we were also able to detect storms in the distance. And last but not least, whales. We detected at least 830 whale sounds in total.”
The researchers worked with Sikt, the Norwegian Agency for Joint Services in Education and Research, which provided access to 250 kilometers of fiber-optic cable in Svalbard, buried on the sea floor between the archipelago’s main city, Longyearbyen, and Ny-Alesund, a research settlement on a peninsula to the northwest . The cable runs from a sheltered fjord called Isfjorden to the open sea.
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