Scientists have captured a rare view of one of the ocean's least understood whales—without ever seeing it. By listening to the sounds beaked whales naturally produce, researchers have reconstructed a three-dimensional picture of their deep-diving behavior in the Gulf of Mexico.
The study provides the first detailed description of the deep-diving behavior of a Gervais' beaked whale (Mesoplodon europaeus) anywhere in the world. Using passive acoustic data alone, the research offers a unique window into how this elusive species moves and forages far below the ocean's surface.
Beaked whales spend most of their lives at extreme depths and surface only briefly, making them exceptionally difficult to study using traditional visual surveys or animal-borne tags. Instead, the research team relied on passive acoustics—underwater listening systems that record whales' species-specific echolocation clicks—to track their movements during deep foraging dives. The approach provides a scalable, non-invasive way to study deep-diving whales and collect data critical for conservation and management.
"These findings come at a critical time for beaked whales in this heavily industrialized region," said Héloïse Frouin-Mouy, Ph.D., lead author of the study and a bioacoustics scientist at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science's Cooperative Institute for Marine and Atmospheric Studies . "There is an urgent need for reliable data on the populations and behavior of these whales, which are believed to be in decline."
Previous research has shown that beaked whale populations in the Gulf of Mexico may have declined by as much as 83% since the 2010 Deepwater Horizon oil spill, underscoring the need to better understand these hard-to-study species and the threats they face.
For the new study, researchers deployed specialized underwater listening systems on the seafloor off the coast of Louisiana at a depth of approximately 1,100 meters (3,600 feet). Two High-Frequency Acoustic Recording Packages, or HARPs, equipped with multiple time-synchronized sensors, recorded echolocation clicks from beaked whales during 50 deep foraging dives. By measuring tiny differences in the time it took each click to reach individual sensors, scientists were able to estimate the direction of the sound. Combining data from both systems allowed them to reconstruct the whales' three-dimensional underwater movements.
The team tracked the dive behavior of three species—goose-beaked, Gervais', and Blainville's beaked whales—and found that goose-beaked whales were detectable for longer periods and tended to make deeper foraging dives than the other species, often approaching the seafloor.
The study marks the first time this acoustic tracking technology has been used to generate detailed dive behavior and movement data for beaked whales in the Gulf of Mexico. The results demonstrate the power of passive acoustics to study some of the ocean's most elusive mammals in regions where traditional research methods are difficult or impractical.
The work was conducted as part of the LISTEN (Long-term Investigations into Soundscapes, Trends, Ecosystems, and Noise) project, an ongoing collaboration led by NOAA's Southeast Fisheries Science Center , Scripps Institution of Oceanography at the University of California San Diego, and other partners.
The study, titled " Beaked whale dive behavior and acoustic detection range off Louisiana using three-dimensional acoustic tracking ," was published February 4, 2026, in the journal PLOS One
This research was funded by NOAA's RESTORE Science Program under a grant to the Southeast Fisheries Science Center for the project "Assessing long-term trends and processes driving variability in cetacean density throughout the Gulf of America (2019–2029)." Additional support came from the Deepwater Horizon Open Ocean Trustee Implementation Group's "Reduce Impacts of Anthropogenic Noise on Cetaceans" project, which aims to restore natural resources injured by the 2010 oil spill.
The authors include Héloïse Frouin-Mouy1, Kaitlin E. Frasier2, John A. Hildebrand2, Eric R. Snyder2, Sean M.Wiggins2, Lance P. Garrison3, Melissa S. Soldevilla3
1Cooperative Institute for Marine and Atmospheric Studies (CIMAS), University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, FL, USA, 2 Scripps Institution of Oceanography, UCSD, San Diego, CA, USA,3 NOAA Southeast Fisheries Science Center, Miami, FL, USA
