UAF graduate student monitors orcas communications with underwater microphones
In the deep blue ocean just off the coast of Alaska, killer whales communicate with each other with clicks and whistles. Scientists hear them.
Hannah Myers listened to many hours of killer whale calls in the Gulf of Alaska. The University of Alaska Fairbanks graduate student often knows a killer whale’s family group after hearing a few syllables of its call.
Using hydrophones (underwater microphones) lowered into the saltwater inlets of a few iconic Alaskan bays, Myers discovered that killer whales are present even in winter, something scientists previously ignored.
Listening to Myers year-round complements decades of work by Dan Olsen and Craig Matkin of the Homer-based nonprofit North Gulf Oceanic Society. Olsen and Matkin have long studied killer whales’ diets, identified individuals with photos, and documented damage from a leaking tanker.
After joining Olsen and Matkin’s team in 2019, Myers has developed a great appreciation for the creatures whose echoes and squeaks she hears in her headphones. Killer whales look a bit like humans in several ways:
â¢ Orcas live about the same age as humans, with females living longer than males.
â¢ Their body temperature is the same as yours and mine.
â¢ Female killer whales go through menopause.
â¢ Killer whales often form groups, family groups led by mother whales which may include their babies, the babies of these babies and even the great great great whales.
Scientists describe killer whales as “cosmopolitan,” meaning they can be found in just about any ice-free ocean on Earth, although most live in cooler waters. At least 50,000 of the elegant black and white mammals enter the salt water today.
Off the south coast of Alaska, there are three distinct groups of killer whales that are almost identical to the naked eye, but likely have not reproduced for hundreds of thousands of years.
Scientists call the first of these killer whales a resident. They mainly eat salmon, preferring chinooks. The residents are the orcas in stable social groups headed by females.
Transient killer whales feed on seals, sea lions, porpoises and other marine mammals. Myers’ sound recordings included the voices of seven transient killer whales who are the only surviving whales of a group devastated by the effects of crude oil released by the Exxon Valdez in 1989. The other seven are from a group of at least 22 members. before this event.
Offshore Killer Whales, found in the deep ocean far from the coast, eat sharks, especially Pacific Dungeness Sharks, with a fondness for their livers.
To learn more about the distribution of these three groups of killer whales throughout the year, Myers deployed hydrophones to three locations in the northern Gulf of Alaska: at the head of Resurrection Bay, which leads to Seward. ; at the entrance to Montague Strait in western Prince William Sound and at the Hinchinbrook entrance, further east in Prince William Sound.
The hydrophones, which Myers and the North Gulf Oceanic Society team retrieve once a year with a grappling hook or by diving for them, are suspended about 10 feet above the seabed. The instruments can detect the vocalizations of a killer whale up to 15 miles away. Whales use clicks for echolocation much like bats do, whistles for close range communications, and repeated calls that are unique to a group.
She also heard strange calls from humpback whales, rain splashing on the ocean surface, waves crashing during storms, and the sound of our species.
âBoat engines are extremely loud, even in a relatively pristine environment like Prince William Sound and Kenai Fjords,â Myers said.
The roar of an oil tanker engine can interfere with the ability of killer whales to communicate or echolocate. The Myers team’s findings may help people help federally protected killer whales, for example by forcing ship captains to cut throttle to reduce engine noise.
Myers’ fieldwork, performed on a 34-foot ship leaving Seward, sheds light on the underwater world off the south coast of Alaska. She listens below the surface to help protect the world’s largest ocean predator.
âWe need to at least know where they are,â she said.