Footage of dolphins at Hong Kong Ocean Park  appearing to self-harm by slamming themselves against the pool wall, recorded by citizen news outlet inmediahk.net, has created a wave of online backlash against the marine mammal center.
During a two-hour visit at the park, which has a marine mammal breeding and research center as well as a marine mammal theme park and amusement park, reporters from inmediahk.net witnessed  various abnormal behaviors of the dolphins, including one of the animals throwing itself into the side of the pool with force, making a loud popping sound.
Ocean Park insisted  that the slamming act is a “unique” habit and that “no injuries or deaths have been sustained as a result of the behavior depicted.”
(Video: reporters from inmediahk.net witnessed various abnormal behaviors of the dolphins.).
Dr. Samuel Hung, the chairman of the non-governmental organization the Hong Kong Dolphin Conservation Society, explained  [zh] in a follow-up interview with the inmediahk.net reporters that the abnormal behavior, however, is a reaction to the enclosed artificial environment of the breeding center:
Although we do not know what's in the dolphins’ mind, such behavior is very rare, in fact it is my first time to see such thing happen. It is very difficult to understand the behavior of a captive animal. Usually they would develop abnormal behavior when their nature is distorted [in an artificial environment]. It is yet too early to say that the act is self-harming and suicidal. What happened  in the Okinawa Marine Museum was suicidal. The dolphin jumped out of the pool during the show. The suicidal act was like a “strike”.
Indeed, the “working conditions” of the dolphins are very disturbing, the reporters observed during the park's annual special program “Animal Month – In High Definition ” [zh]:
劇場的四條海豚，長期處於高噪音環境下，劇場表演前為了娛賓，公園會派出樂隊作半小時的表演，另外14條海豚在研究中心也受到濾水器噪音長期折磨。海豚靠聽力覓食，發出聲響後可捕捉100米以內食物，聽覺頻率為1-150kHz 而人類聽覺頻率為 0.02-17kHz ，而最高可聽到40-100kHz。就算是一個普通人也抵受不了，何況是一條聽覺靈敏的海豚！
The four dolphins in the Ocean Theater are working in a very noisy environment: a live band usually performs on stage to entertain the tourists before the dolphins appear on stage. As for the 14 dolphins in the research center, they are also tortured by the water filter system round the clock. Dolphins rely on hearing to capture fish in the sea within 100 meters. Their auditory frequency is 1-150kHz., while human hearing frequency is 0.02-17kHz and the highest frequency audible to human is 40-100kHz. When human find the sound annoying, the sensitive dolphins would find it a torture!
Four dolphins were all together in the tiny pool of the Ocean Theater, three of them were constantly reviewing the performance routine before the show started; and the other one was forced to stay in a half-meter deep pool for the tourist program “Dolphin Encounter”. Under the instruction of the trainer, the dolphin had to entertain the tourists with different postures. While the tourists were lining up in queue to take a picture with the dolphin, the trainer had to press the dolphin's head and body to make sure that it would not struggle and hurt the tourists. Ocean Theater provide performances four times a day, about 30 minutes per session. As in recent years, the number of park visitors keeps increasing, apart from the pressure of performances, it is difficult to estimate the psychological torture derived from special tourist programs such as “Dolphin Encounter” and “Kiss the Dolphin”.
The Ocean Park was initially a government-initiated project set up in 1977 and funded by the Hong Kong Jockey Club  to “assist in the understanding and practice of wildlife conservation”. The park ceased to be a subsidiary of the Hong Kong Jockey Club in 1987 and became an independent statutory body, the Ocean Park Corporation, with a board appointed by the government.
The amusement park also operates observatories, laboratories, an education department, and a whales and dolphins fund. The world's first dolphin born by artificial insemination was born in Hong Kong  back in 2001. But the death of dolphin babies usually goes unnoticed because of the lack of a public monitoring mechanism  [zh]:
Since 2012, how many babies dolphins have died in the park? There is no public monitoring mechanism and no public report. The number remains a mystery. Moreover the park has not announced any “sensitive” information such as the ratio of male and female dolphins, ages, relations, origins, death records, and breeding records. As a public research center, how can it play the role of educator without basic transparency? How can it educate people about conservation if it does not respect life?
On social media, people expressed their concern for the animals at the center. Doris Woo, a secondary school student, commented  in Facebook:
將心比己 如果將你成日困喺屋企個浴缸到 應該唔會再想生存落去
Just imagine that you were locked in the bath tub at home, you would not want to live. The Ocean Park is now commercially run.
Lam Chet Yan, a local university student, pointed out :
Dolphins have very sensitive hearing. The noise comes from the water filter system has already created too much pressure for them. The noise of tourists during their performance will make them crazy. Don't watch the show. Although they look as if they are smiling, their stress is immersive. Don't go to the zoo. What can you learn from the captive animal anyway? Or you think we can exploit animal like this for pure entertainment?
A petition calling for Ocean Park to phase out cetacean captivity had 809 signatures  on Change.org as of May 28, 2013:
Please add my voice to those opposed to the Dolphin exhibit at Ocean Park. Concrete tanks cannot replicate the expanse of the ocean, nor can they fulfill the physical or psychological needs of these bright, social creatures.
Marine amusement park spectators see animals in captivity, where instinctive behaviors are lost in a made-for-profit world. Dolphins belong in the ocean, where they normally swim 100 miles a day. Swimming around a tank 500 times just to cover 50 miles is cruel punishment. […]
No matter how “state of the art” your facility may be, it simply cannot duplicate natural habitat. Wild dolphins live to 50; those in captivity rarely survive their teens. The National Marine Fisheries Service states that over half of all captured dolphins die in under two years. Survivors average 5.8 years in captivity. Socially bonded dolphins go insane when attempts to communicate through bouncing sonar waves create “boomerang” reverberations that literally bounce back at them. Many aquariums stock Pepto-Bismol to treat stress ulcers. Chlorinated tanks can cause dolphins to go blind and suffer skin disorders. Many succumb to pneumonia, ulcers or other stress-related illnesses.
Please consider diverting funds for this project toward local conservation efforts or other educational alternatives such as real-time videos of rehabilitation efforts broadcast into an “aquarium theater”, on to the internet, or into classrooms.
Trapped marine mammals are sad caricatures of the real thing. Please do not subject more creatures to pain and suffering for the sole purpose of public amusement.