Embattled marine theme park SeaWorld will be allowed to expand its killer whale habitat, a California commission said Thursday. But the approval came at a steep price: The company will not be permitted to breed the animals while in captivity, a practice that animal rights activists have called inhumane.

SeaWorld has come under fire for its treatment of the animals in captivity. It has been subject to increased public criticism, and as a result, its stock price has plummeted and its CEO resigned in December.

The California Coastal Commission approved the company's $100-million expansion of its orca tanks, which would nearly double in size to 10 million gallons. But the new breeding restrictions make it likely that the 11 orcas that are currently in captivity will be among the last.

Animal rights activists were ecstatic over the outcome of the months-long process that ended with a unanimous vote by commissioners Thursday night.

"SeaWorld has admitted that it intended to breed even more orcas to fill the new tanks, but the commission’s action today ensures that no more orcas will be condemned to a nonlife of loneliness, deprivation, and misery if SeaWorld proceeds with their Blue World project," People for the Ethical Treatment of Animals said in a statement. "SeaWorld is a sea circus, and the orcas are its abused elephants."

Ultimately, PETA said it hopes SeaWorld will be forced to stop building tanks and instead send the orcas to coastal sanctuaries where "they’d finally have some semblance of a natural life."

But SeaWorld noted that preventing the orcas currently in captivity from breeding is itself inhumane.

“A ban on breeding would sentence these animals to a slow extinction in our care,” John Reilly, president of SeaWorld San Diego, said as he left Thursday night's meeting, according to the Los Angeles Times.

The park added in an official statement that it would "carefully review and consider" its options after the vote.

Joel Manby, President and Chief Executive Officer of Sea World, said the company is "pleased that the Commission recognizes the benefits of the planned expansion," but is "disappointed with the conditions they have placed on their approval."

"Depriving these social animals of the natural and fundamental right to reproduce is inhumane and we do not support this condition," Manby added in his statement.

The proposal will also restrict the sale, trade or transfer of orcas -- though SeaWorld will be permitted to house beached or rescued animals, subject to approval from government agencies.

SeaWorld promises that the Blue World Project will be like "no other experience... in the world." The massive tank will be more than 50 feet deep with 1.5 acres of surface area. The tank will include "fast water current" that will allow the killer whales to swim across moving water.

"Guests can walk alongside our killer whales as if at the shore, interact with them at depths found in the ocean, or see them from a bird’s eye view," the company says.

One commissioner said officials were torn by a desire to see the animals freed, but noted that they couldn't say no to a project that would give the animals more space to roam.

"Most people would agree that at least trying to increase the size of the habitat that they live in is better than what they live in now,” Commissioner Greg Cox told the Los Angeles Times.

PETA claims that SeaWorld's breeding process subjects the animals to unethical treatment. Instead of allowing them to breed with a mate of their choice as they do in the wild, SeaWorld trainers artificially inseminate female orcas with the sperm of males in captivity.

"Male orcas are trained to float on their backs, and their trainers masturbate them to collect their sperm," PETA said. "Females are artificially inseminated and forced to breed at a much younger age than they would in nature."