Dolphins are trained to carry out these tricks by a reward based system, they are fed a fish every time they successfully perform a trick.
This means to ensure the dolphins will perform they must be maintained hungry. They are fed an adequate amount of food throughout the day but the food is staggered so the dolphins are desperate enough to perform the trick.
Staff in interactive marine parks will tell tourists the dolphins carry out the tricks voluntarily but really they are just obeying an order so they can eat.
Captive dolphins are kept in a state of perpetual hunger !
Exposure to Noise
Dolphins have been scientifically proven to have extremely sensitive hearing. No dolphinaria park takes this into consideration and dolphins and other marine mammals are exposed to extremely loud noises from morning till evening. They are exposed to loud music, constant whistling, people laughing, shouting, children screaming, etc.