NEWS RELEASE
Northern elephant seals were repeatedly captured on camera in the deep Pacific Ocean using sonar from an Ocean Networks Canada (ONC) observatory as a dinner bell to forage for their next fish feast, according to a new study by a University of Victoria visiting scientist.
The research study published in the peer-reviewed PLOS ONE journal provides a unique first-ever visual glimpse into the elusive mammal’s deep sea underwater behaviours, with a focus on their sophisticated feeding strategies, prey preferences as well as resting habits.
Altogether, at least eight male elephant seals, ages four to seven, were observed on camera and detected by hydrophones during multiple visits to the 645-metre-deep research site at Barkley Canyon along ONC’s subsea cabled observatory NEPTUNE off the British Columbia west coast between 2022 and 2023.
The findings came almost by chance; a team led by ONC senior scientist Fabio De Leo that involved researchers from UVic and the Instituto de Ciencias del Mar, a Barcelona-based research institute, was studying the effects of light and bait on fish and invertebrate behaviour at Barkley Canyon, using a high-definition camera, acoustic imaging sonar, hydrophone, pair of LED lights, and automatic bait release. But a review of the camera, acoustic images and sound data revealed the surprise visitors.
“We suspect the seals have learned to associate sonar noise from the research instrument with the presence of food — a phenomenon known as the “dinner bell” effect. The seals appeared to use this sound to locate an area with prey and may take advantage of fish disturbed by the camera lights, particularly targeting sablefish, their preferred meal as seen in the video footage,” says Héloïse Frouin-Mouy, lead author of the publication.
Frouin-Mouy, a visiting scientist at UVic in the department of biology and assistant scientist at the University of Miami, collaborated on this research with Francis Juanes, UVic biology professor and Liber Ero Chair for Fisheries Research, and adjunct professor Rodney Rountree. ICM-CSIC’s Jacopo Aguzzi and ONC’s Fabio De Leo Cabrera are also co-authors on the paper.
In one instance, the repeated visits over 10 days by four of the identified seals to the research site also demonstrates that they quickly learnt to use the infrastructure to forage for food more efficiently, adds Dr. Frouin-Mouy.
“We became familiar with the mammals and ended up naming them in the paper after members of The Beach Boys to differentiate between the frequency of visits and observed habits,” she says.
The frequent seal visitors, named after The Beach Boys. Credit: Ocean Networks Canada
The adolescent males visiting the site predominantly targeted actively swimming sablefish, ignoring the over dozen other stationary or drifting prey options. Several individuals were interestingly recorded on camera and hydrophone bobbing their heads and producing low frequency sounds while chasing prey.
Sonar videos also revealed seals power-napping on the seafloor at Barkley Canyon, another new and never before seen behaviour from the adolescent male northern elephant seal.
A rare visual glimpse of a sleeping northern elephant seal on seafloor at Barkley Canyon. Credit: Ocean Networks Canada.
NEPTUNE’s real-time monitoring capacity allowed the researchers to adapt the use of ONC’s subsea instruments deployed at the research site for fish study to pick up on the presence of the seals and observe them for nearly a year.
Dr. De Leo says this experiment was the first of its kind in the deep-sea, and it aimed to observe and listen to the sounds produced by any species that visited the site.
“It took us a lot of time to design the perfect geometry of the instrument platform in order to make the sonar and the video camera field of views to nearly precisely overlap to record the same area of the seafloor,” he explains. “One other very tricky and laborious element of this project was the development of a piece of software (driver) to control all the recording settings of the imaging sonar. Remember, we are remotely controlling an instrument that’s nearly 100 km offshore and nearly a kilometre deep in the ocean!”
Although northern elephant seal colonies are found as far north as Alaska and southern towards Baja Peninsula, they are typically studied using biotags to track movement, or found primarily on land.
More data from the fish acoustics experiment are still being analyzed by the whole team, but the video imagery itself has already contributed to four publications; this one on elephant seals and three others which helped to develop machine learning algorithms to automatically detect sablefish and some of its striking behaviours.
This research aligns with UVic’s commitment to the United Nations Sustainable Development Goals, and with its strengths in climate action, life below water, life on land, and sustainable cities and communities. Learn more about UVic’s climate traction.
Ocean Networks Canada
Ocean Networks Canada (ONC) operates world-leading observatories in the deep ocean and coastal waters of the Pacific, Atlantic, and Arctic coasts of Canada as well as the Southern Ocean, collecting ocean data that accelerates scientific discovery and makes possible services and solutions for a resilient planet. ONC’s cabled observatories supply continuous power and Internet connectivity to scientific instruments, cameras, and 12,000-plus ocean sensors. ONC also operates mobile and land-based assets, including coastal radar. ONC is an initiative of the University of Victoria and is funded by the Canada Foundation for Innovation and the Government of Canada.
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A media kit containing high-resolution photos, audio clips, and video is available here.
Media Contacts
Mike Gregory (Ocean Networks Canada) at 672-974-7202 or mikegregory@uvic.ca
Jennifer Kwan (University Communications and Marketing) at uvicnews@uvic.ca
About the University of Victoria
UVic is one of Canada’s leading research-intensive universities, offering life-changing, hands-on learning experiences to more than 22,000 students on the edge of the spectacular BC coast. As a hub of transformational research, UVic faculty, staff and students make a critical difference on issues that matter to people, places and the planet. UVic consistently publishes a higher proportion of research based on international collaborations than any other university in North America, and our community and organizational partnerships play a key role in generating vital impact, from scientific and business breakthroughs to achievements in culture and creativity. Find out more at uvic.ca. Territory acknowledgement.
