Killer whales go on 'unprecedented' killing spree off California

FILE 2015: A female killer whale and her newborn calf are seen in this handout photo. (Reuters)

Killer whales off the coast of Monterey Bay have reportedly chalked up their fourth kill since last Thursday after separating a helpless gray whale calf from its mother.

Scientists called the killing spree in the area “unprecedented.” In the case of the gray whale calf, sightseers on a whale watching tour had front-row seats during the hunt. The San Francisco Chronicle reported that whale watchers have been able to see, firsthand, hunts that are usually only seen in productions.

“This has never happened in my thirty years," Nancy Black, a marine biologist with Monterey Bay Whale Watch, told The Chronicle. "Just to witness that out in nature when you usually see that kind of thing on television is really spectacular."

Monterey Bay historically is a favorite spot for orcas to intercept migrating gray whales.

The most recent killing occurred on Wednesday. Although it usually takes hours for killer whales to kill a grey whale calf—due in part to the fact that these calfs’ mothers usually give a valiant effort to protect their young, using their massive tails to strike at the orcas and-- at times -- roll over with the calf on their bellies—the killing on Wednesday took only 20 minutes.

Black told the paper that the mother and calf in this case appeared to be thinner than usual, hence may have given up a lesser fight. She said it may be a record how fast the pod of nine whales killed the calf.

Young orcas swam nearby to observe how the females approach the kill.

"Mothers and calves are last to migrate because they stay in Mexico longer so their calves can grow up and gain weight before they make that long migration," Black told the paper.