A seal pup on St. Paul Island
Pup counts of northern fur seals on St. Paul Island in the Bering Sea have been crashing, and one knows why.
Certain types of killer whale — those silent, secretive marine-mammal eaters known as “transients” — have been prowling off shore. But what are they doing?
Could they be scarfing down seals when no one’s looking? How do you spy on predators and prey hidden within the green-dark Bering Sea?
You eavesdrop.
University of Alaska Fairbanks grad student Kelly Newman has been using a special undersea recording device to capture the bumps, whistles, cries and clicks of transient killer whales off a seal rookery in St. Paul Island.
Newman played a middle-of-the-night recording at a recent science conference in Anchorage: There was a whomp or two, then an otherworldly vocalization by a killer whale.
Was it a kill followed by a call to dinner? Perhaps.
The project, which ran for 22 days last June and July, produced intriguing evidence that killer whales are munching on northern fur seals in the dark, when human researchers sleep snug in their beds. Newman, working with UAF oceanographer Alan Springer, hopes to return next summer for another listen.
In the opague universe beneath the waves, marine mammals navigate and find prey with sound. Tracking what they do and where they go by using special underwater recording devices has become one of the neatest tricks in scientists’ kits.
The North Gulf Oceanic Society has monitored killer whale activity in Resurrection Bay for years with a listening phone deployed at Thumb Cove. Pioneering research that pinpointed critical habitat and late-summer migrations of the endangered North Pacific right whale hinged on data gathered by listening phones planted on the ocean floor.
AP writer Dan Joling described Newman’s research in a story published Tuesday in the Anchorage Daily News.
With limits on what her eyes could contribute to her research, Newman turned to her ears.
Using a sophisticated hydrophone, the graduate student last summer captured the distinctive sound of orcas killing — pouncing on seals or ramming them like freight trains, often at night, then calling in their companions to share in feeding.Newman says her work, so far just a pilot project, affirms that visual observations are limited in determining behavior of marine mammals, especially if the animals don’t want to be seen.
“You may see a killer whale, and you may see a fur seal, and you may see something going and maybe think there might be predation, but you can’t be sure,” she said.