If you've seen Humpback Whales hunt schools of fish the same thing happens. The whales drive the fish to the surface and surround them with bubbles and then they all swim toward the surface in unison (the same way every time, btw - they always emerge in the same pattern), mouths open, and eat as much as they can. Sometimes birds go after the fish at the same time and get swallowed. There was a thing on "Nature" where a cameraman caught a whale swallowing a bird and then it spit it out a minute later, it was "fine" but probably a bit confused.