I'm A Bad Man

CNN has one of their user-submitted "news" stories on the site right now.

Beached Pilot Whales Euthanized

It's got a few pictures of people trying to "return the whales to the water".

"About 35 whales that had stranded themselves on Kommetjie beach have been euthanized after efforts to rescue them failed.
[...]
As we were walking away, we heard the shots - a sound that will stay with me for a long time."


So ... what's an appropriate caliber for whales? (According to Wikipedia, adult males are up to 20ft and 3 tons.)

I'm thinking rifle caliber starting with .3 or higher...