Saturday, August 25, 2007

Did a Killer Whale take a bite out of this Humpback Whale's tail?

What do you think? Sure looks like something tried to dine on this close-call Humpback. If the missing chunk of tail isn't clue enough, check out those teeth marks! My guess is that a Killer Whale (Orca) may have attacked this whale in a prior year as it migrated to its Arctic feeding grounds. Likely, it was a juvenile at the time and somehow its mother was able to shield it from an organized attack by “transient” Killer Whales.

Transients are just what the name implies, roving opportunists with no particular home base, who follow food sources across great distances. Unlike the “resident” pods of Killer Whales from Washington state and British Columbia who mostly eat fish, the transients prey on marine mammals including Gray Whales and Humpback Whales (generally vulnerable juveniles).

A few years ago The San Francisco Chronicle reported on the pod of transient Killer Whales that was picking off baby Gray Whales near Monterey Bay. It seems the transients consider Monterey Bay a stop on their tour - spring means whale meat followed by seal season in the summer. Last winter individuals from Washington’s resident pod came all the way down to the Farallones but surely these salmon eaters didn’t mistake a Humpback for a Coho. The third photo is another recently spotted example of a Humpback who may be another Killer Whale predation survivor.

Researchers identify individual Humpbacks through photo identification, gathering data on migration, population size, health, and human impact. A whale’s tail, or fluke, at 10 or more feet wide, and no two alike, is ideal as a photo ID. Cascadia Research of Olympia, Washington has been coordinating this effort. Their linked study also mentions entanglement and boat strikes as causes for some of the disfiguring irregularities they see in photo records of Humpbacks.

The perfect images of a whale fluke that we all admire have as much to do with the whales’ good luck as the photographers’.

Photos by Ed Estes. Text by Kathleen Jacques.

No comments: