SAN JUAN ISLAND, Wash. (AP) — At dawn, a group of scientists initiated an innovative experiment by unspooling over a mile of fiber-optic cable into the icy depths of the Salish Sea. This project aims to create a continuous underwater microphone system capable of capturing the vocalizations of local whale populations, particularly the endangered Southern Resident orcas. The research is driven by the urgency to understand how these marine mammals cope with challenges such as ship traffic, food availability, and the effects of climate change.
The technology being utilized is known as Distributed Acoustic Sensing (DAS), traditionally used to monitor pipelines for structural issues. Researchers from the University of Washington are now adapting this technology to enhance our understanding of oceanic ecosystems. Unlike conventional hydrophones that only capture sounds from fixed points, DAS transforms the entire length of the fiber-optic cable into an extensive sensor capable of accurately pinpointing an animal's location and direction as it swims.
Shima Abadi, a professor at the University of Washington Bothell School of STEM, emphasized the potential of this technology: “We can imagine that we have thousands of hydrophones along the cable recording data continuously,” he stated. The preliminary tests have demonstrated promising results with large baleen whales, as evidenced by recent recordings of fin and blue whales along the Oregon coast, using existing telecommunication networks. However, the vocalizations of orcas pose a significant challenge due to their high-frequency sounds, which have yet to be captured using this method.
The Southern Resident orcas are critically endangered, with a population that currently numbers around 75 individuals. These orcas are facing formidable threats, including noise pollution from maritime activities, toxic contaminations, and a marked decline in their primary food source—the Chinook salmon. Data from the Pacific Salmon Commission shows that Chinook populations have plummeted by 60% since tracking began in 1984, largely due to habitat destruction, overfishing, damming, and climate change.
Orcas rely on echolocation—rapid clicks that bounce off objects—to locate their prey in the often murky waters of the Salish Sea. Unfortunately, the noise produced by passing ships can disrupt these clicks, making hunting increasingly difficult. The successful implementation of DAS technology could offer conservationists invaluable real-time data. For instance, if orcas are detected traveling towards Seattle, authorities could be alerted to minimize vessel noise, thus facilitating a safer environment for the whales.
Moreover, this technology holds the promise of answering foundational questions regarding orca behavior. Researchers hope to uncover insights into how orcas communicate across different social contexts and how their hunting strategies may vary during cooperative behaviors. Furthermore, the system could develop a form of acoustic recognition, identifying distinct calls from individual whales.
The potential applications of this technology reach beyond the Salish Sea. With approximately 870,000 miles (1.4 million kilometers) of fiber-optic cables already laid across the ocean floor globally, the infrastructure necessary for a wide-reaching oceanic monitoring system is largely in place. “One of the most critical challenges for managing wildlife is the profound lack of data available,” stated Yuta Masuda, director of science at Allen Family Philanthropies, which supports the project.
The timing of this research is significant, particularly as the High Seas Treaty is set to come into force in January. This legislation will enable the establishment of new marine protected areas in international waters. However, current scientific understanding of human impact on numerous ocean species remains insufficient. A comprehensive dataset gleaned from the global network of submarine cables could help determine priority areas for conservation efforts.
As the team on the barge engaged in the meticulous task of fusing fiber strands while facing challenging marine conditions, they successfully created a functioning connection. Data began transmitting back to shore, visualized as cascading waterfall plots that record sound frequencies over time, with cameras on standby to correlate specific vocalizations with observed behaviors of the orcas. All that remained was for the researchers to monitor the waters for their elusive subjects.
