I spent the first half of my twenties working in marine biology, in research, education, and entertainment. That was several decades ago and one of the facilities no longer exists. In research, I worked in the lab across the hall from David and Melba Caldwell. They were very interesting people (She told me she couldn't stand Mozart... "all tinkle, tinkle, tinkle sounds"

).
Once in a while, after my work day was done, I would go play catch with the dolphins. They had basket balls to play with and enjoyed playing with people. I always ended up soaking wet after one of those sessions... They would make sure to gulp a big mouthful of water before hurling the ball and the water to me. Then they would tail dance on the water making sounds that sure sounded like laughter to me.
The complex I worked for was dedicated to marine mammal protection and had stopped capturing, buying, or otherwise acquiring wild dolphins by the time I worked there. Any new dolphins were acquired from birth. The complex put a lot of time, expense, and effort into rescuing stranded dolphins, porpoises, and small whales (pilot, pygmy sperm whales, etc.). Most of the time, by the time these whales and dolphins beached themselves, they were too sick to save despite all efforts to do so. But when they were able to be saved, they were rehabilitated and released back into the ocean.
I visited Sea World after working in the smaller complex for a while, and I immediately hated it. It was slick and polished; the showmanship was impressive. The tourists were treated like cattle and there was minimal, if any, attempt to educate them about marine mammals. While I'm sure that the individuals who worked with the marine mammals developed a caring relationship with them, one did not get the feeling that those up the corporate ladder, or even those who worked in the park, but away from the whales and dolphins, had the same. Pretty much the opposite of the complex I worked in where the top brass (under the Board of Directors) all had worked their way up from the bottom rungs of the complex, and those who worked in the park could do as I did after their work hours.
I learned the history of the complex, which, for many years was the expert, first and last word, in dolphin research and knowledge. In the early days, dolphins were not considered much more than exotic fish. The early research (several decades before my time there) was horrific (in my opinion -- they were not tortured, but they were killed so dissection could be done). in light of what we now know about them now. It was not long before knowledge of dolphins and smaller whales evolved -- and with it standards of treatment toward dolphins and whales at this facility.
From history, I have come to believe that marine parks should not keep marine mammals. Marine mammals that have been born in captivity, and who have never lived in the wild present a problem. I don't know if they can be taught how to survive in the open ocean. They are very intelligent, but it seems to me it would be like taking an undocumented person who was brought to the US as a baby being deported, without the language, the knowledge of customs or culture, and without a support system, to the land of their birth. That person might survive and thrive. And might not.
I came across this article regarding what we have learned from dolphins in captivity. I guess the question is, could we humancentrics have learned to love and respect dolphins and whales without this knowledge. And how do we put a stop to putting all animals in captivity?
The author plans to "confront the ethical arguments related to captive research" in future articles.
http://www.awesomeocean.com/2015/09/30/awesome-research-captive-bottlenose-dolphins-taught-us-part-1-introduction-early-history-study-dolphin-communication/
Introduction: Early History and the Study of Dolphin Communication
Aquariums can take credit for first brining dolphins and whales to the world’s attention as remarkable mammals that have family life and social behaviour analogous to other mammals. Before this these animals were seen merely as sources of meat, oil and leather products. -Professor Murray A. Newman co-founder of the Vancouver Aquarium (1994)
Imagine a world without Flipper (or my generational equivalent, Darwin from Sea Quest DSV), without aquariums and without a concept of smart, social dolphins. Before the first half of the 20th century this was the world we lived in. It was a world without a Marine Mammal Protection Act that treated marine mammals as commodities if they could be exploited and nuisances if they could not be commercialized.
There was no campaign to “Save the Whales” and no impetus to want to protect these animals in the wild. This reality changed when the first captive dolphins, taken to be little more than background scenery in underwater adventure films, charmed us with a gregariousness and affability that soon drove millions to want to see them up close and in person.
In this first article, I will address the early history of captive research as well as how the study of dolphin communication is informed by captive studies. Each part of this series will explore the role captive animals have played in our understanding of their wild counterparts as well as how our opinions of dolphins have been shaped by our interactions with zoo housed individuals. I will also consider the role captive animals still have play in developing our understanding of evolution, cognition, ecology and conservation.
More at link