Thermal IR cameras "see" whales by measuring the apparent temperature differences between the mammals and the surrounding water and air when they surface and exhale.
(Images by Dan Zitterbart and Craig LaPlante, Woods Hole Oceanographic Institution)
For ferry-goers gliding through the calm and sometimes narrow channels of British Columbia’s Gulf Islands, the views can be idyllic: craggy coastlines and placid inlets set against lush forested mountains. But for endangered Southern Resident Killer Whales (SRKWs), of which fewer than 80 remain, the area has become increasingly dangerous.
Whales there face a range of threats, including potential contamination from oil spills from commercial ship accidents, and Persistent Organic Pollutants (POPs) which infiltrate ocean sediments and accumulate in Chinook and Chum salmon—important food sources for resident killer whales.
Noise pollution is another problem for these mammals. According to a report published by the Canadian government, noise from ships drowns out whale communications, which in turn affects their ability to find mates and also reduces the distance over which they can detect food using echolocation clicks. In fact, these killer whales may lose up several hours of foraging time per day from noise-related disturbances.
A growing concern
Vessel traffic in the region has increased significantly in recent decades, making whales more vulnerable to ship strikes along these quaint marine highways. Depending on the severity, collisions can seriously injure or kill whales, and may also knock passengers on smaller vessels off their feet or throw them into the air.
“Some of the passages are very narrow, which increases the chance of vessel strikes since whales and boats share the same waterways for travel,” said Dan Zitterbart, an assistant scientist at Woods Hole Oceanographic Institution. “This not only applies to killer whales, but to humpback whales as well, which are growing in population in this area.”
Vessel traffic in British Columbia’s Gulf Islands has increased significantly in recent decades, making whales there more vulnerable to lethal vessel strikes along these narrow marine highways. Researchers are testing the effectiveness of thermal IR cameras for automated whale detection, which could help prevent collisions. (Photo on left by Dan Zitterbart, Woods Hole Oceanographic Institution. Photo on right by Harald Yurk.)
A surveillance system for whales
To help mitigate the potential for collisions, Zitterbart, who received a 2019 Young Investigator Program (YIP) award from the Office of Naval Research for his work in developing next-generation whale detection systems, is working with British Columbia Ferry Services, Inc. and Transport Canada to install and test thermal IR (infrared) cameras to monitor inlets for the presence of whales. The cameras are being installed at a ferry terminal on Galiano Island on a test basis and will scan the mile-wide entrance of Active Pass for whale blows for the next year and beyond.
Thermal imaging cameras detect whales by measuring the apparent temperature differences between the animals and the surrounding water and air when they surface and exhale. And, they work independent of daylight, so unlike other whale detection methods such as human observation from planes and boats, they can spot whales around the clock. This is important since commercial vessel traffic operates during non-daylight hours.
“Testing thermal imaging as a whale detection tool and comparing its efficiency with that of other detection technologies, such as acoustic detection, will allow us to determine how often whales travel through a waterway without vocalizing,” said Harald Yurk, a scientist with DFO. “At the end of the test, we will be able to determine if a single detection method will be sufficient to reliably detect whales in these waterways and potentially lower the risk of ship strikes, or if a combination of systems will be more advantageous.”
For the cameras to work reliably, it’s important that they’re able to distinguish between whales and boats in a congested channel. Out of the box, a thermal IR camera wouldn’t know the difference, so the cameras are linked to a computer running in the background that has been “trained” on model images of vessels and whales. This helps minimize the number of falsely-identified “whales” that are reported by the cameras.
“We’ve made these detection algorithms more robust so they can perform reliably in an environment where some of the objects that come into view may look similar from afar,” he said.
Acoustic monitoring is already used in the narrow waterway, but adding a dedicated optical whale surveillance system is a proactive step that may help reduce the risk of a possible strike even further. The technology is not without its limitations—dense fog and rainfall can impair camera accuracy—but if the initial testing goes well, Zitterbart may try expanding the application.
“This work is only one part of the overall solution to preventing vessel strikes,” he said. “But if the detection is effective enough, we could eventually think about mounting infrared cameras directly on the bow of ferry ships and having a real-time feedback loop where mariners are alerted to slow down if whales are present.”
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit www.whoi.edu.