“Who thought it was a good idea to put a whale in a pool?” Howard Stern recently wondered on his satellite radio program.

The shock jock’s comment hints at just how much public scrutiny of captive orca shows has increased, driven by well-organized animal advocates and written into a new bill to outlaw the practice that was introduced in Congress last week.

SeaWorld—the most famous keeper of orcas, also known as killer whales—responded on Monday by announcing sweeping changes to programs at its flagship San Diego location, including phasing out the “Shamu” orca act.

SeaWorld’s strategy documents, posted online Monday, say the company will replace that act with a more "informative" experience in a more natural setting that will carry a "conservation message inspiring people to act."

The developments come amid reports of falling admission to its 11 parks around the United States. SeaWorld’s share prices have also been sliding steadily since a series of high-profile demonstrations by animal advocates, spurred by the successful 2013 documentary film Blackfish, which cast a critical eye on the marine entertainment industry.

SeaWorld had fought back with public statements defending what it calls humane treatment of orcas and pointing to the rescue and conservation work the company underwrites. (Read more about the captive whale controversy.)

But animal advocates say that Monday's announcement could mark a turning point in their war against keeping orcas captive. Public opinion has shifted “in favor of ending the archaic and cruel practice of keeping orcas in captivity,” said Jared Goodman, PETA Foundation’s director of animal law, in a statement.

U.S. Congressman Adam Schiff (D-Burbank), who on Friday introduced federal legislation that would prohibit the breeding of captive orcas, end the capture of wild orcas, and stop the import and export of the animals, agrees.

“The decision by SeaWorld to phase out killer whale shows in San Diego is a welcome step along the path towards ending the captivity of these magnificent creatures,” he says.

More Bans on Captive Orcas

In recent years, everyone from schoolchildren to the musical acts Cheap Trick and Willie Nelson have publicly boycotted SeaWorld.

“With captive facilities such as SeaWorld being promoted since childhood, especially for those of us raised in the US, as ‘good clean fun’ and traditional family vacation destinations, it is incongruent for many to consider the dark underbelly of captivity,” the Whale and Dolphin Conservation group writes on its website.

A 2014 survey by that group found that half of American adults oppose the practice of keeping orcas in captivity, a rise of 11% since 2012.

There are 57 captive orcas around the world, but at least 14 countries have passed laws that prohibit their captivity, including India and several countries in Europe and Latin America. Similar laws have also passed in South Carolina and New York.

Earlier this year, the California Coastal Commission ruled that SeaWorld could no longer breed its orcas in the state. SeaWorld has not said what its plans are for its killer whale shows at its Orlando and San Antonio locations.

The company did not immediately respond to a request for comment on Monday.

“I would urge the company to curtail the breeding of their orcas and partner in the creation of ocean sanctuaries,” says Schiff.

PETA’s Goodman also says SeaWorld’s proposed changes don’t go far enough. “Changing the tanks or the style of show is not going to meaningfully relieve the animals of suffering,” he says.

Concerns for Orca Health

“The public is upset about their suffering and the movie Blackfish was the beginning of the end for the practice,” Goodman says.

Problems for the animals in captivity include breakup of wild orca pods, stress, and the killing of human trainers, including the high-profile killing of SeaWorld trainer Dawn Brancheau in 2010.

“Unfortunately, after all the years of experience that I had, I saw the psychological and physical trauma that results from captivity,” former SeaWorld trainer John Hargrove previously told National Geographic. “A massive corporate entity is exploiting the hell out of the whales and the trainers.”

Correction: A previous version of this story said there were an estimated 2,000 captive orcas around the world. There are an estimated 2,000 captive cetaceans of all types and 57 captive orcas.

Jane J. Lee contributed reporting for this story.