The research team of Graeme Ellis and Michael Wetklo of the Pacific Biological Station, Lance Barrett-Lennard of the Vancouver Aquarium, and Craig Matkin of the Alaska's North Gulf Oceanic Society have made an interesting discovery.
Orcas routinely snack on regional sharks, with Pacific sleeper sharks (Somniosus pacificus) being the main prey item.
The team have been focusing on tooth wear found on dead animals, a wear pattern that suggested a rough skinned prey. Unfortunately the wear pattern is causing enamel loss and tooth infection found in many animals.
"This represents the first confirmed prey species of offshore killer whales based on field observations of foraging and the first record" of Pacific sleeper sharks as the prey of killer whales anywhere, the study said.