San Juan Island, Wash. — At dawn over San Juan Island, a team of scientists stood on the deck of a barge and unrolled more than a mile of fiber optic cable into the cold waters of the Salish Sea. Working with headlamps, they fed the line from the rocky coast to the seafloor, home to the region’s orcas.
The bet is that the same hair-thin strands that carry internet signals could be transformed into a continuous underwater microphone to capture the clicks, calls and whistles of passing whales, information that could reveal how they respond to shipping traffic, food shortages and climate change. If the experiment works, the thousands of miles of fiber optic cables already crisscrossing the ocean floor could become a vast listening network that could inform conservation efforts around the world.
The technology, called Distributed Acoustic Sensing, or DAS, was developed to monitor pipelines and detect infrastructure problems. Now, scientists at the University of Washington are adapting it to listen to the ocean. Unlike traditional hydrophones that listen from a single point, DAS turns the entire cable into a sensor, allowing it to identify an animal’s exact location and determine the direction it is heading.
“We can imagine that we have thousands of hydrophones along the cable continuously recording data,” said Shima Abadi, a professor at the University of Washington Bothell School of STEM and the University of Washington School of Oceanography. “We can know where animals are and learn about their migration patterns much better than with hydrophones.”
Researchers have already shown that the technology works with large baleen whales. In a test off the Oregon coast, they recorded the low-frequency rumbles of fin whales and blue whales using existing telecommunications cables.
But killer whales present a bigger challenge: Their clicks and calls operate at high frequencies where the technology has not yet been tested.
Fighting for survival
There is a lot at stake. The southern resident killer whales that frequent the Salish Sea are endangered, with a population of around 75 individuals. Whales face a triple threat: underwater noise pollution, toxic pollutants and food shortages.
“We have an endangered orca trying to eat an endangered species of salmon,” said Scott Veirs, president of Beam Reach Marine Science and Sustainability, an organization that develops open-source acoustic systems for whale conservation.
The Chinook salmon that orcas depend on have declined dramatically. Since the Pacific Salmon Commission began tracking numbers in 1984, populations have declined by 60% due to habitat loss, overfishing, dams and climate change.
Orcas use echolocation, rapid clicks that bounce off objects, to find salmon in murky waters. Boat noise can mask those clicks, making them difficult to hunt.
If DAS works as expected, it could give conservationists real-time information to protect whales. For example, if the system detects orcas heading south toward Seattle and calculates their travel speed, scientists could alert Washington state ferries to postpone noisy activities or slow down until the whales pass.
“It will surely help with dynamic management and long-term policy that will have real benefits for the whales,” Veirs said.
The technology would also answer basic questions about orca behavior that have eluded scientists, such as determining whether their communication changes when they are in different behavioral states and how they hunt together. It could even allow researchers to identify which sound is coming from a particular whale, a sort of voice recognition for orcas.
1 / 23 | Wonders of the sea: an intimate look at whales and dolphins in their natural habitat. Every year on July 23, World Whale and Dolphin Day is celebrated. – Alberto Ortiz
Beyond the Salish Sea
The implications extend far beyond the Salish Sea. With some 1.4 million kilometers of fiber optic cables already installed underwater globally, the infrastructure for ocean monitoring largely exists. It just needs to be taken advantage of.
“One of the biggest challenges for wildlife management, biodiversity conservation and combating climate change is that there is simply a lack of data in general,” said Yuta Masuda, chief science officer at Allen Family Philanthropies, which helped fund the project.
The moment is critical. The High Seas Treaty will come into force in January, allowing for new marine protected areas in international waters. But scientists still don’t understand how human activities affect most ocean species or where protections are most needed. A data set as vast as the global undersea cable network could provide could help determine which areas should be prioritized for protection.
“We think this has a lot of promise for filling those key data gaps,” Masuda said.
Back on the barge, the team faced a delicate task: fusing two fibers above the surf. They struggled to align the strands in a fusion splicer, a device that precisely positions the ends of the fiber before fusing them with an electric current. The ship rocked. They steadied their hands and tried again, and again. Finally, the weld held.
Soon, data began flowing to a computer on shore, appearing as waterfall charts, cascading visualizations that show sound frequencies over time. Nearby, cameras focused on the water were ready so that if a vocalization was detected, researchers could link a behavior to a specific call.
All that was left was to sit and wait for the orcas.