I was just standing on researcher Ken Balcomb’s kitchen porch looking out at Haro Strait, from Washington toward Vancouver Island, Canada, watching killer whales going by.
Cool enough, but these were not the usual “residents” who hunt salmon. They were “transients;” mammal eaters. One way we knew: We’d been listening to the nearby hydrophones set up by orcasound.net (you can eavesdrop too, on the Web) but we heard nothing when we noticed the whales coming around the corner. The fish-eaters are chatterboxes, very vocal. The transients are silent stalkers, hunting with their sonar but being quiet about it, so they don’t give their location away to mammals they hunt.
Ken saw a seal pop its head up and go down. Ken said the seal wasn’t reacting evasively, adding, “reaction right now is crucial.”
Suddenly several male killer whales were surging through a spreading slick under and a couple of dipping gulls.
Then I saw one of the whales surface momentarily with a piece of the seal.
The 3 males that were in on that kill are about 27 feet long and weigh about 17,000 pounds. The seal they ate weighed about 250 pounds and was gone in under a minute.
The so-called transient, mammal-eating killer whales have been showing up increasingly in recent years. They continue to benefit from the increasing seal numbers following the Marine Mammal Protection Act of 1972. In such slow growing, long-lived creatures as killer whales, their recovery, following the lengthy recovery of the seals they hunt for food, is a decades-long proposition.
That’s the good news. The situation is more difficult for the fish-eating killer whales, whose food—salmon—have been severely depleted. The whales’ fate follows the fate of their food.