Killer whales kill and then abandon a harbor porpoise off San Juan Island

On September 9, 2009, researchers who were tracking southern resident killer whales in Haro Strait noticed whales from J- and K-pods interacting with a harbor porpoise.

Three specific whales (J31, J36 and J39) spent the most of the time with the porpoise and J-31 was seen using its head to throw the harbor porpoise in air on two occasions. The entire interaction lasted over 30 minutes.

The whales continued interacting with the carcass after the porpoise had died then finally left the carcass floating at the surface. After the whales left the area the porpoise was collected with authorization of the San Juan County Marine Mammal Stranding Network and delivered it to Friday Harbor Laboratories.

We necropsied the porpoise and found numerous "rake" marks (from killer whale teeth) on the porpoise, but most were superficial and did not even penetrate through the blubber. There was evidence of hemorrhage (bleeding or bruising) in the lungs, likely from being hit into the air several times by J-31.

This is the 4th porpoise necropsied by SeaDoc and the San Juan County Marine Mammal Stranding Network that has been killed by resident fish-eating killer whales. All of them were left floating once the porpoise died.

For great pictures taken by Robin Baird during the event, see: http://www.cascadiaresearch.org/robin/kwseptember09.htm