{"id":804374,"date":"2026-07-15T22:25:25","date_gmt":"2026-07-15T22:25:25","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/804374\/"},"modified":"2026-07-15T22:25:25","modified_gmt":"2026-07-15T22:25:25","slug":"stalking-silence-in-svalbard-norse-scientists-unveil-new-method-for-tracking-silently-moving-objects-in-the-water","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/804374\/","title":{"rendered":"Stalking Silence in Svalbard: Norse Scientists Unveil New Method for Tracking Silently Moving Objects in the Water"},"content":{"rendered":"

Scientists from the Norwegian University of Science and Technology<\/a> have unveiled a method for tracking silently moving underwater and surface objects<\/a> by using existing fiber-optic cables<\/a> to measure water displacement<\/a>.<\/p>\n

The scientists behind the novel detection approach, which was designed to detect whales<\/a> even when they aren\u2019t vocalizing<\/a>, also demonstrated the method\u2019s ability to track surface ships<\/a> and potentially underwater vessels, such as submarines<\/a>, that traditionally rely on silence for stealth<\/a>.<\/p>\n

Tracking Silently Moving Whales and Other Objects<\/p>\n

In the research team\u2019s study<\/a>, the authors explain that it is already possible to record and reconstruct marine<\/a> mammal vocalizations, including those of whales, using seabed fiber-optic cables. They note that the current method, called distributed acoustic sensing<\/a> (DAS), allows scientists to passively monitor whale behavior, \u201cenabling both the detection of vocalizations and the simultaneous tracking of multiple individuals.\u201d<\/p>\n

However, they add, although this data can prove valuable in tracking these increasingly endangered<\/a> animals, \u201cit has not been possible to track marine mammals when they are silent.\u201d<\/p>\n

\u201cA fundamental limitation of passive acoustic monitoring is that most methods rely on acoustic data, which is only available when whales vocalize,\u201d the study authors explain, adding that this limitation \u201cclearly demonstrates the need for new sensing methods that can detect silent whales.\u201d<\/p>\n

Although the researchers propose several methods, including combining DAS data with satellite<\/a> and observational data to paint a more complete picture, they also note a \u201csecond path\u201d that involves exploring current datasets to discover new, valuable acoustic signatures<\/a> even when the animals are silent.<\/p>\n

Detecting Hydrodynamic Pressure Changes Caused by Ships and Animals<\/p>\n

When exploring new ways to interpret DAS data collected by seabed fiber-optic cables, the team explained how low-frequency strain variations may arise from \u201ca range of physical mechanisms.\u201d These include hydrodynamic processes \u201cassociated with moving objects.\u201d<\/p>\n

For example, the authors explain, when a ship moves across the ocean surface, it pushes water ahead of it and draws water along in its wake. This motion through the water medium generates a strain on the surrounding water described as a hydrodynamic pressure field. According to the team, this motion-induced pressure field \u00a0\u201cextends downward through the water column.\u201d<\/p>\n

\u201cThe displacement of water generated by moving whales and ships induces a moving hydrodynamic pressure field that extends through the water column, dynamically loading and unloading the seafloor,\u201d they explain.<\/p>\n

Changes in this pressure field caused by moving objects cause sediments on the ocean floor to deform laterally and vertically. In areas of the seafloor with fiberoptic cables buried underneath, the DAS system records this \u201clateral deformation\u201d of the sediments, which \u201ctranslates into strain that can be observed in the DAS data.\u201d<\/p>\n

\u201cThis means that no acoustic signal is involved, and we can \u2018listen\u2019 to silent whales,\u201d they write.<\/p>\n

Tests Demonstrate Tracking Surface Ships and Submerged Whales<\/p>\n

To calibrate their approach, the team used surface ships as \u201cproxies\u201d in a series of field experiments. According to their study, the four interrogator units (IU) were installed \u201cduring the DAS experiment on Svalbard in 2022.\u201d Then, another unit was installed in Longyearbyen in March 2025. Although the study focuses on the newer IUs, the team notes that all the experimental data \u201cwas used to analyze how coupling affects the detectability of hydrodynamic pressure field signatures and how the signal characteristics change with increasing source-receiver distance.\u201d<\/p>\n

In those experiments, the team investigated four ships of different sizes. Notably, all ships were observed at a depth of 70 to 80 meters and were traveling at roughly the same speed. Critically, ship size, speed, and route data can be verified externally, providing a check on the study\u2019s results.<\/p>\n

\u201cShips are observed in the DAS data year-round, and the AIS is available to confirm which ship is sailing above the fiber and at what time,\u201d they explain.<\/p>\n

As expected, they found that the DAS signal amplitude \u201cscales with the size of the ship.\u201d For example, the smallest ship they observed barely registered above the background noise, making it the hardest to track. Conversely, the largest vessel tracked by the team, an icebreaker, left the clearest signal.<\/p>\n

The researchers also demonstrated the ability to observe hydrodynamic pressure and velocity signals from a cruise ship at a water depth of 413 m, \u201cand up to 550 m from the fiber cable.\u201d However, when the team searched for whales, the range was much more limited.<\/p>\n

\u201cThe smaller blue whales can be observed when diving within 40 m of the fiber-optical cable,\u201d they explain.<\/p>\n

During a dedicated test segment, the team monitored what they interpreted as several silently moving whales traversing through the detection zone. Although they were unable to independently confirm they were whales in the same way they could confirm the ships, the team notes that \u201cmultiple lines of analysis support the interpretation that whales are\u00a0responsible for the observed signals.\u201d<\/p>\n

The team also notes that AIS data confirmed that no acoustic ship signatures were present \u201cin the time window studied.\u201d They add that this result \u201creduces the likelihood that the observed low-frequency signals originate from vessels.\u201d<\/p>\n

The Signal Amplitude Decreases with Increasing Distance From the Fiber<\/p>\n

When discussing the implications of their findings, the team said their data shows that the observed low-frequency response captured by the fiber-optic cables \u201cis consistent with translating hydrodynamic pressure fields generated by the displacement of water by moving ships and other large bodies such as whales.\u201d<\/p>\n

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\u201cThis sensing method enables an approach to monitoring one of the world\u2019s most endangered species,\u201d they explain, adding that it is even more effective at detecting submerged objects than at detecting surface ships.<\/p>\n

\u201cA fully submerged object generates a more symmetric pressure field, while a surface-bound ship produces a truncated field due to the air\u2013water interface, which limits the downward extent of the pressure field,\u201d the study authors write.<\/p>\n

When discussing the limitations of their innovative, silent, object-tracking approach, the team notes that it is only effective for tracking smaller ships and whales at close range.<\/p>\n

\u201cKvitungen is the smallest ship investigated in this work and is barely observed above the noise floor for a water depth of \u223c75 m,\u201d they write. \u201cBlue whales are even smaller and are unlikely to be detected at distances greater than approximately 30 to 40 m from the fiber.\u201d<\/p>\n

The team also notes that although larger ships generate stronger signals than smaller ones, \u201cthe signal amplitude decreases with increasing distance from the fiber.\u201d<\/p>\n

Other limitations involved data returns suggesting whales that were either \u201cabnormally long or surprisingly small.\u201d The team said this seemingly impossible result \u201cunderlines that our simple model needs further development to obtain more precise results.\u201d<\/p>\n

The study \u201cDetecting silent whales using seabed fiber-optic cables<\/a>\u201d was published in the Proceedings of the National Academy of Sciences (PNAS).\u00a0<\/p>\n

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X<\/a>, learn about his books at plainfiction.com<\/a>, or email him directly at christopher@thedebrief.org<\/a>.<\/p>\n

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