Protect the young

On my last whale watch trip, right at sun set tonight, I witnessed two orca bulls trying to kill a humpback whale calf.  The calf was surrounded by 4 to 6 adult humpbacks, though, and I think they may have been on all sides of the calf and even underneath it.  The orcas were driving all around the group of humpbacks.  I had to leave to get my group back to the dock before it was settled, but I never saw any blood and think the humpbacks were successful in protecting the calf.