A SEAWORLD orca has died from an infection after allegedly being held in a tiny tank where he was bullied by other whales for 20 years.
Tragic Nakai passed away on Thursday night despite the best efforts of veterinarians and health specialists at the park in San Diego.
The 20-year-old killer whale was born into captivity at SeaWorld in September 2001 and was the first of his species to be conceived through artificial insemination.
SeaWorld San Diego announced on Friday that Nakai had died surrounded by carers who had worked closely with him over the last two decades.
They said: "Every attempt was made to save [Nakai’s] life.
"Veterinarians and health specialists had been actively treating an infection, but aggressive therapeutic and diagnostic efforts were unsuccessful.
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"He’ll be remembered as a curious and quick learner, often picking up behaviors just by observing the other whales in his pod."
His aptitude made him the ideal candidate for hearing studies to help scientists better understand the impact on orcas of noise from ships and other human activity.
But animal rights campaigners have slammed the park for glossing over Nakai's years of "torment" confined in a tank.
In the wake of the orca's death, People for the Ethical Treatment of Animals (PETA) announced they had obtained footage of a "violent attack" between killer whales at the park.
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They claim a concerned SeaWorld visitor sent them a video of the brawl that resulted "in a serious wound to at least one of the animals."
It is unclear if Nakai was involved in the incident.
The shocking clip shows two orcas clashing in the water while a horrified youngster can be heard saying: "How is it still alive? I thought they hug each other, not fight each other."
PETA said the guest described how they saw "blood soaking the water" from the allegedly injured animal.
They also claimed to have seen "bite marks and fresh wounds all over the side of the whale".
Tracy Reiman, PETA’s executive vice president, said: "In two days, one orca has died and another has been attacked by other frustrated, tightly confined orcas, leaving him with a serious injury — and young children as witnesses to the carnage."
The footage has fuelled claims that the killer whales were being kept in cramped tanks with "incompatible" marine mammals.
PETA also referred to a similar incident in 2012, when Nakai was left with a huge chunk of flesh missing from his jaw after a performance with two other whales.
'ALTERCATION' BETWEEN ORCAS
But SeaWorld insisted that the wound was caused by the killer whale coming "into contact with a portion of the pool".
However, Dr. Ingrid N. Visser, founder and principal scientist of the Orca Research Trust, noticed "puncture marks that match orca teeth spacing" on Nakai.
He said it was a clear indication that "an altercation between the orcas was involved."
A SeaWorld spokesperson told the that the latest video was "misleading and misconstrued".
They also referred to two recent scientific papers, arguing the clip showed "common orca behaviors exhibited by both wild populations and those in human care as part of natural social interactions."
But PETA has filed a fresh complaint with the U.S. Department of Agriculture (USDA), calling on the agency launch a fresh probe into the "stressful" conditions animals are confined in at SeaWorld.
They claim the marine park has violated the Animal Welfare Act, despite being warned in the past.
With Nakai’s death, there are now eight killer whales remaining at SeaWorld, ranging in age from 9 to 57 years old.
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The firm announced they were ending their breeding program in March 2016, following years of campaigners railing against them.
The Sun have contacted SeaWorld for comment.