This was taken probably 20 yards (18 m) off shore, there is a steep drop off here.
The Dolphin was quickly circling and slapping his tail to confuse the fish. Next step could be to push these fish on shore for the Dolphin to follow for a quick grab.
Instead the whirlpool did the work and the Dolphin was able to feed right there, no herding to the beach needed.
Click, or double tap, any image to view the gallery.