There have been a record number of sightings of so-called "transient" orca whales this year in the Puget Sound area of Washington.

The mammal-eating orcas have been putting on quite a show for whale watchers as they hunt and capture their prey. But, while the transient orcas are thriving, the fish-eating resident orcas in the area are struggling to survive.

Ken Balcomb, a whale biologist and the director of the Center for Whale Research, explains one theory for the uptick in transient whale sightings is that they've been called in by the resident orcas to get rid of some of seals who are competing with the orcas over a dwindling supply of fish.