Submarine Internet Cables Become "Ears" to Protect Whales — The Unexpected Potential of Communication Cables

One of the infrastructures supporting communications when watching overseas videos or exchanging messages with distant parties is the submarine cable.

The cable laid to carry human information might also play a role in alerting the presence of whales swimming in the sea.

The sounds emitted by whales travel through the sea and cause minute deformations in the submarine cable. By interpreting these changes, it is possible to detect the calls and, under the right conditions, estimate their location and movement. This concept utilizes communication infrastructure as an observation system to monitor marine life.

Introduced by ZME Science on November 12, 2026, the potential of this technology and the challenges in advancing from research to practical application are highlighted. The background includes the accumulated research by Cornell University's bioacoustics researcher, Lea Buffo, and a review published in the academic journal "Methods in Ecology and Evolution."

A system to constantly track whales worldwide is not yet complete. However, by changing the way we use existing submarine infrastructure, a path has opened to listen to the sea, which has been difficult to observe until now.

Why can sound be detected with "just a cable"?

This technology is called "Distributed Acoustic Sensing," abbreviated as DAS.

Typically, to study underwater sounds, hydrophones, which are equivalent to underwater microphones, are used. However, installing numerous observation devices in the vast ocean and continuously inspecting and retrieving them requires ships, manpower, and costs.

In DAS, laser pulses are sent into the optical fiber. A portion of the light is scattered by minute irregularities within the fiber and returns to the device.

When vibrations from whale calls and other sources are added, the fiber slightly stretches and contracts, changing the properties of the returning light. By analyzing these differences, it is possible to determine where along the cable the changes occurred.

In other words, instead of emitting sound into the water to locate whales, the system reads the impact of the received sound through light.

While conventional underwater microphones primarily measure sound pressure at the installation point, DAS measures changes in strain at numerous points along a long fiber. Therefore, a single cable functions like a "long ear" with multiple observation points.

It should be noted that the research uses spare fibers within communication cables that are not in use. It is not a technology that analyzes the content of users' emails or videos to locate whales.

A 120-kilometer cable becomes about 30,000 observation points

A study published in 2022 utilized an existing submarine communication cable off the coast of the Svalbard Islands in Norway.

The research team used a section of about 120 kilometers as approximately 30,000 measurement points at 4-meter intervals, detecting low-frequency calls of blue whales and fin whales.

Even just knowing that "whales are near the cable" is valuable. However, if the same call can be captured at multiple points, even more information can be obtained.

The time it takes for sound to reach each point on the cable varies slightly depending on the distance from the sound source. By examining these time differences, it is possible to estimate where the sound originated.

Especially if there are two cables, it becomes easier to narrow down the left-right positional relationship, which is difficult to discern with just one. The equipment for recording sound evolves into equipment for studying movement.

1,808 calls in 5 hours, tracking the movement of 8 whales

A study published in 2023 analyzed 5 hours of data obtained from two fiber optic cables in the Arctic, detecting 1,808 calls of fin whales.

The research team used part of this data to track the movement of 8 whales, being able to simultaneously follow up to 4 whales. Calls from locations up to about 9.4 kilometers away from the cable were also detected.

Here, the number 1,808 does not represent the number of whales. Since the same individual may call repeatedly, the number of calls cannot be directly translated into population size.

Additionally, the "approximately 100-meter positional accuracy" demonstrated in the study has conditions. This result was obtained using test sounds emitted from a ship with known positions to verify the estimation method. It does not mean that the position of any whale can always be determined with the same accuracy anywhere in the ocean.

Nonetheless, reconstructing the movement of multiple whales from existing submarine infrastructure is a significant achievement in expanding the observation range.

By 2026, also detecting the calls of bowhead whales

Until now, DAS using communication cables has mainly focused on capturing the large, low calls of blue whales and fin whales.

On the other hand, detecting higher frequency or weaker calls has been a challenge.

According to Cornell University's announcement in November 2026, Buffo collaborated with local whaling groups and wildlife management departments in Utqiaġvik, northern Alaska, in the spring of the same year. By analyzing DAS data obtained from Quintillion's cables, the calls of bowhead whales were detected for the first time.

This result indicates the potential to expand the range of observation targets. However, it does not mean that all baleen whales can be detected in the same way in all sea areas.

The goal of researchers is not to replace all conventional underwater microphones. It is to complement areas lacking marine information by combining different observation methods.

A future where whale calls lead to warnings for ships

One reason for the anticipation of this technology is its application in preventing ship-whale collisions.

For example, detecting calls near shipping routes and estimating their location. By combining this information with the ship's location data, it can alert approaching ships and navigation managers. If this leads to decisions such as slowing down when necessary, it could potentially reduce the risk of accidents.

However, there is still a gap between research on detecting whales and the operational systems that actually reduce accidents.

Is the time until a warning is issued short enough? Can detection occur even in noisy areas with ship sounds? What is the extent of false alarms or missed detections? Can the recipients of the information actually respond?

In monitoring using calls, the absence of detected calls alone cannot be used to conclude that "there are no whales."

The expectation is not to entrust the safety of the sea to a single device but to add a new information source to visual and conventional acoustic observations.

Surprised reactions on social media, but distinguish from reactions to this article

The idea of using submarine cables for whale observation has also garnered interest on social media.

As an example, science writer Ryan Green introduced related coverage he wrote on LinkedIn. He explained that he deepened his coverage after learning about the interest in the world of submarine cables and research on detecting when whales are not calling.

The post received short comments such as "very impressive" and "interesting article," indicating that the unexpectedness of gaining insights into animal behavior from submarine communication equipment piqued readers' interest.

However, this post introduces another related study dealing with the detection of non-calling whales. It cannot be treated as a direct reaction to the current ZME Science article or the November review.

Within the scope confirmed this time, there was not enough material to gather numerous reactions to the latest article and determine trends in public opinion. While surprising and favorable reactions seen on social media can be introduced, it is not appropriate to expand this to "praised worldwide."

What determines practical application is "conditions" rather than cables

Hearing that existing infrastructure can be used might make it seem like simply connecting devices completes the observation network. In reality, several conditions need to be met.

First, the data volume is large. Recording numerous points at fine time intervals can generate information on the scale of several terabytes per day, depending on the settings. A method where humans check everything makes continuous monitoring difficult.

The accuracy of automatic analysis to distinguish whale calls from ship noise and earthquake signals is crucial.

Next, there are differences in sensitivity for each cable. The way they are structured, how they contact the seabed, and the surrounding environment can change how the same sound is captured. A successful setting in one sea area cannot necessarily be applied directly to another.

Furthermore, there are restrictions on access to usable fibers and optical relay devices. Not all sections of cables laid worldwide can be used for observation simultaneously.

In terms of costs, having existing cables does not mean that observation can continue for free. Measurement devices, analysis infrastructure, data storage, and personnel for operation are needed.

To expand the technology, cooperation with not only researchers but also communication operators, the marine industry, and related organizations is essential.

Points of contact between communication and marine observation to consider in Japan

The significance of reading this research in Japan is not limited to "an interesting experiment conducted overseas."

In Japan, surrounded by the sea, if communication infrastructure can also be utilized to understand the marine environment, it becomes an option to expand the value of existing infrastructure.

As future considerations, it is possible to use the system to understand the timing of whale appearances in areas with heavy ship traffic or to examine changes in underwater sound before and after coastal development. However, these are application examples that can be considered from the results introduced this time and do not mean that the same system is already in practical use in Japan.

When considering implementation, it is necessary to confirm the types of animals and the frequency of their calls to be observed, as well as the location and usage conditions of the cables. It is also essential to design from the beginning who will receive the obtained information and what decisions it will be used for.

The important thing is not just converting cables into observation devices. It is about what we can learn about the sea and what actions can be taken as a result.

Submarine cables laid for human connection are beginning to convey the previously unreachable calls of whales to us. This potential is already being demonstrated in experiments.

Sources and References

1. ZME Science: Introduction to DAS mechanism, past experiments, and challenges for practical application.
   https://www.zmescience.com/science/oceanography/the-internets-underwater-cables-could-double-as-a-whale-monitoring-network/

2. Cornell University: Introduction of 2026 research. Detection of bowhead whale calls, publication of review, and complementary relationship with conventional observations.
   https://news.cornell.edu/index.php/stories/2026/11/repurposing-internets-backbone-advance-whale-monitoring Cornell Chronicle

3. Frontiers in Marine Science, 2022 paper: Research detecting baleen whale calls using submarine optical fibers around the Svalbard Islands.
   https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.901348/full frontiersin.org

4. Frontiers in Marine Science, 2023 paper: Detection of 1,808 calls, tracking of 8 whales, maximum detection distance of about 9.4 km, verification conditions of position estimation method.
   https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1130898/full frontiersin.org

5. Cornell University, 2022 explanation: Differences between DAS and underwater microphones, utilization of unused fibers, challenges of processing large amounts of data.
   https://news.cornell.edu/stories/2022/07/existing-fiber-optic-cables-can-monitor-whales Cornell Chronicle

6. Ryan Green's LinkedIn post: Introduction of another related report dealing with whale detection using submarine cables and reader comments. Not a direct reaction to the latest article. Comments summarized in Japanese.
   https://www.linkedin.com/posts/ryan-green-15b423195_the-global-web-of-subsea-cables-that-connects-activity-7493723128406106112-c_VG