With that, after a half-century of tail splashes and orca acrobatics, the marine mammal park closed its final Shamu show.

The business of killer whale entertainment is a half-century old. It has changed dramatically since its formation. It is now illegal, under the Marine Mammal Protection Act, to import or display orcas without first passing expert review and a 30-day public comment period, after which the National Oceanic and Atmospheric Administration may issue a permit.

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But in 1965, orca entertainers required little more than gumption and $8,000 in cash. A Washington man named Edward Griffin had both, plus, apparently, sturdy forearms: Before he purchased a 22-foot-long killer whale, captured by British Columbia fishermen, he defeated one of the Canadians in an arm-wrestling match.

Griffin’s fantasy, as The Washington Post reported in 2015, was to ride a killer whale in the manner of an aquatic stallion. It was a dream Griffin realized in a tank at the Seattle Marine Aquarium, which he owned. The $8,000 animal he rode was called Namu, in honor of the British Columbia fishing port.

Namu died after spending a year at the Seattle aquarium. But before his death he inspired a legacy of performing whales. Griffin obtained a second whale; SeaWorld, the marine mammal park in San Diego that had opened just a few years before, bought her secondhand. By January 1966, the aquarium taught Shamu to leap out of the water on command. Griffin refused to part with the rights to the name Namu, so the California park added a “sh.” Future performing orcas, too, would come to be known as Shamu.

Over the next 50 years, the Shamu shows became more complex, with trainers riding on the whales’ snouts and orcas performing flips like 4-ton gymnasts. Throughout that half-century, SeaWorld reinvented the performances, adding new tricks or changing choreography. SeaWorld, in its parks in San Diego, Orlando and San Antonio, is currently home to 22 orcas in the U.S.

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“Each of the killer whales knows probably a couple hundred behaviors,” Alan Garver, now SeaWorld’s vice president of zoological operations, told the Los Angeles Times in 2011. “In developing new stuff for a show, a lot of it is combining those behaviors together in new ways.”

The final iteration of the Shamu show, a performance named One Ocean, began in 2011. (Prior to One Ocean, the Times estimated that SeaWorld put on some 40,000 orca shows at the San Diego park alone.) The One Ocean show promised, per the SeaWorld website, to envelop audiences “in a multi-sensory celebration of life underneath the sea that entertains as it educates and inspires.” But it lacked what trainers called water work, in which humans would interact with the whales in the tank.

The year prior, an orca named Tilikum killed a trainer and SeaWorld billboard model, Dawn Brancheau. Tilikum grabbed Brancheau by the hair and pulled her into the water. An autopsy found she died from blunt force trauma to the head, neck and upper body, with fractured ribs and a jaw, as ABC News reported in 2010.

The trainer was dead before rescuers pulled her body from the water. Tilikum, linked to two previous human deaths, himself died Friday at SeaWorld’s Orlando park.

Tilikum and Brancheau were the tragic center of the movie “Blackfish,” the 2013 documentary that painted an ugly picture of captive orcas. Kept from their natural environment in the wild, the animals became aggressive and neurotic, according to “Blackfish,” and aquariums could not provide adequate care for the animals.

“It’s hard to imagine anyone coming out of this movie and not swearing off the next vacation trip to Orlando, San Antonio or San Diego,” Washington Post movie critic Michael O’Sullivan wrote after the film’s release. (SeaWorld, which had declined to be interviewed for the documentary, disputed that its animals were maltreated and alleged that “Blackfish” was “emotionally manipulative” propaganda.) The Occupational Safety and Health Administration also took note of Brancheau’s death, effectively banning SeaWorld employees from swimming with the whales.

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The film prompted a damning public response, sometimes called the “Blackfish” effect: SeaWorld share prices dropped and attendance fell. In March 2016, SeaWorld chief executive Joel Manby, in an op-ed for the Los Angeles Times, acknowledged that the company was in a bind.

“Customers visit our marine parks, in part, to watch orcas,” he wrote. “But a growing number of people don’t think orcas belong in human care.” SeaWorld was ending its breeding program, he announced. By September 2016, the California legislature banned orca breeding in all marine parks. Shares hit a record low in August, though Manby, reported the Guardian, did not attribute the further drop to a boycott.

Discussion of “Blackfish” even breached the walls of Shamu stadium Sunday. “I resent the people who did that film,” one attendee told the San Diego Union Tribune. Still, attendees packed the stadium to the gills to watch the One Ocean show come to a glittering and wet finale.

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The next iteration, Orca Encounter, is set to open in the summer as SeaWorld transitions to larger tanks. The aquarium has branded the Orca Encounter as a more educational experience than an entertaining one. “The new Orca Encounter takes killer whale presentations to a new level of education,” Marilyn Hannes, the San Diego park’s president, told the Times of San Diego in November, offering information on “natural history, physical abilities and the conservation steps necessary to ensure the future survival of this species in the wild.”

In place of an LED whale tail, for instance, the new tank will be surrounded by “a rugged coastal inlet, artificial Douglas fir trees, cliffs and waterfalls,” the San Diego Union Tribune reported.

“The fountains, the style of music, the style of theatrics from our trainers, that’s all moving away,” Brian Morrow, a SeaWorld vice president, said to CBS News on Friday.

But trainers will continue to cue the animals, which the aquarium says is a necessary part of keeping the animals healthy and stimulated. “You will still see a whale leaping out of the water,” Garver told the Tribune. “We want to be able to demonstrate behaviors people would see in the wild with the killer whales and their abilities as a top predator in the sea.”

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Not all animal advocates have rushed to applaud the changes. “The trainers aren’t safe, and the whales aren’t happy,” Gabriela Cowperthwaite, the filmmaker behind “Blackfish,” said in an interview with CBS News. “They’re still just doing manic circles around concrete swimming pools.”

Naomi Rose, an orca biologist at the nonprofit Animal Welfare Institute who opposes whale captivity, expressed hope to the Tribune that SeaWorld will no longer have whales somersault through the air — a behavior foreign to wild whales, she pointed out.

Although SeaWorld will no longer breed whales, it expects to have orcas for years to come. The youngest captive orca in San Diego, Amaya, was born in December 2014. The life span of killer whales in captivity is disputed, but SeaWorld veterinarians argue that the whales should live as long as their wild counterparts, an average of 30 years or so for female orcas like Amaya.