I have a theory. My theory is that dolphins don't fish. Dolphins don't hunt for fish. What they do is play. Play with each other, in the wakes of boats and anywhere else they want. While doing this they incidentally come across fish and eat them which satisfies their need for food. But they never go out looking for food.
Of course, when you watch documentaries about how they "heard" schools of fish into shallow waters or into columns of confusion you might think that this theory is not true or a bit wacky. But consider this. When they are herding and controlling these fish are they hunting or are they playing? Are they like the modern man when he goes hunting? The man who hunts for sport and not the need to eat. The enjoyment of the hunt and not the necessity of the hunt.
So do dolphins fish for food? Or are they just playing?