The fiber optic cables delivering your Netflix might help monitor endangered species

Fiber optic cables crisscross the world’s ocean like a spiderweb, transmitting vast amounts of data as pulses of light. What if they could also be used to listen in on life below the waves? An experiment just launched in coastal waters on the northwestern edge of the United States could soon provide answers. In mid-October, a team of scientists at the University of Washington laid nearly two kilometers of fiber optic cable onto the seafloor in the San Juan islands, clustered near the Canadian border.

Now they are waiting to see if they can listen in on the movements of endangered whales. “This innovative approach could be a breakthrough in conservation efforts,” said Shima Abadi, an oceanographer at the University of Washington’s Bothell campus, who is leading the research.

The Salish Sea, a small extension of the Pacific Ocean, is frequented by a group of 74 orcas protected under the Endangered Species Act. The rarity of the Southern Residents, as they are known, and their proximity to major population centers including Seattle and Vancouver, British Columbia make them a major subject for study by scientists.

Much about the whales remains a mystery, however, partly because they spend much of their time out of sight underwater. Researchers have already tapped into underwater microphones to monitor the orcas, part of a growing movement to monitor wildlife using sounds. But there are major gaps in coverage from these hydrophones. Fiber optic cables, by contrast, are ubiquitous, totaling 1.4 million kilometers strung at the bottom of the ocean.

In recent years, scientists have shown they can tap into this network to monitor for earthquakes. Researchers in Norway have reported being able to detect ships, storms, quakes and whales with these cables. This new initiative is focused on tracking the movements of a species based on the sounds they make distinctive clicking produced for echolocation. “We hope to show that fiber optic cables can detect Southern Resident orca vocalizations, enabling us to triangulate the orcas’ locations and better track them—allowing earlier warnings to vessels to reduce speed or avoid the area,” said Abadi.

The approach works by tapping into what might seem like a weakness. Vibrations can cause deformations in the hair-thin filaments that make up the core of a fiber optic cable, disrupting light as it passes down the cable.

To watch for these disturbances, scientists attach a device that transmits pulses of light down the cable and detects subtle changes that reflect some of the light back to its source. Those reflections can be analyzed to pinpoint the location and the distinctive vibration signature of, say, a whale’s call. The method is known as distributed acoustic sensing, or DAS. While two kilometers of cable isn’t much and these orcas are just one species, scientists involved in the work are thinking much bigger.

“Our hope is that this distributed acoustic sensing trial will lead to the creation of a global monitoring network that protects endangered species like the Southern Resident orca,” said Yuta Masuda, director of science for Allen Family Philanthropies, which contributed $1.5 million to fund the project. Photo: ©University of Washington