Killer whales leave porpoises for dead

Scientists are grasping for answers to explain why southern resident killer whales — a group of fish eaters that prefer chinook salmon — have also been observed toying with harbour porpoises before leaving them dead, including two cases in the past month in Washington state and B.C.’s Strait of Georgia.
Joe Gaydos, staff scientist with the SeaDoc Society, speculated in an interview Tuesday that killer whales might see the porpoises as an opportunity for a playful “cat and mouse” game — albeit with deadly consequences.
“The thing we forget about wildlife is that they don’t really have a consciousness like we have, that this is okay and this is not okay,” he said from his office in Washington’s San Juan Islands.
A 2005 paper co-authored by Gaydos reported the discovery of 13 dead harbour seal pups in the San Juan Islands. It found evidence of a “novel pattern of killing without intent to eat” by “one or more transient killer whales” — a separate group that targets marine mammals and not fish — although resident killer whales could not be completely exonerated in connection with the seal deaths.