Story highlights PETA says SeaWorld "has taken a step forward but more must come"

SeaWorld has been under fire about its treatment of orcas since the 2013 documentary "Blackfish"

"SeaWorld has been listening and we're changing. Society is changing and we're changing with it," the company said

(CNN) The killer whales currently in SeaWorld's care will be the last generation of the mammals enclosed at the water parks, according to a company announcement posted on its website.

"Why the big news? SeaWorld has been listening and we're changing. Society is changing and we're changing with it," the company said. "SeaWorld is finding new ways to continue to deliver on our purpose to inspire all our guest(s) to take action to protect wild animals and wild places."

The company has come under fire for its treatment of killer whales since the 2013 CNN documentary "Blackfish." That film profiled one of its whales, Tilikum, who has been involved in the deaths of three people, including SeaWorld trainer Dawn Brancheau in 2010.

Reports recently surfaced that Tilikum may be dying. He is estimated to be 35 years old.

Photos: Killer whales in captivity Photos: Killer whales in captivity Lolita, a captive killer whale at the Miami Seaquarium, was added to the endangered species listing for Southern Resident Killer Whales by NOAA Fisheries in February. Although her species was already listed as endangered, Lolita was not previously included because there was an exemption for captive members of the population. Lolita has been at the Miami Seaquarium since 1970. Hide Caption 1 of 8 Photos: Killer whales in captivity Killer whales, or orcas, were first put on public display in the 1960s. The best known killer whale shows in the United States are at SeaWorld Parks, which are synonymous with their "Shamu" killer whale shows, seen here. Hide Caption 2 of 8 Photos: Killer whales in captivity SeaWorld's first park opened in San Diego, California, in March 1964 with only a handful of employees, a few dolphins, sea lions, and two aquariums. The park introduced orcas the next year, and they quickly became the stars of the park's shows. A steady stream of celebrities have posed with SeaWorld's killer whales, including actress Halle Berry, seen here in 2009. Hide Caption 3 of 8 Photos: Killer whales in captivity SeaWorld opened its Orlando park in 1973, where the first killer whale was born in captivity in 1985. SeaWorld emphasizes that it is "dedicated to education, entertainment, research and conservation" of all its marine animals. Here, two orcas at SeaWorld Orlando perform in 2000. Hide Caption 4 of 8 Photos: Killer whales in captivity The 1993 hit movie "Free Willy" captured hearts and sparked a massive campaign to free Keiko, the orca that played "Willy" in the movie, from the Mexican amusement park where he performed. Here, Keiko is being prepared to be released into the wild in 1998. In 2002, Keiko spent five weeks journeying across the Atlantic to Norway. He wasn't quite ready to be independent, finding companionship among the Norwegian fishermen and children. He died in December 2003, most likely from pneumonia. Hide Caption 5 of 8 Photos: Killer whales in captivity A male killer whale, Bingo, is transported to the Nagoya Port Aquarium in Japan in December 2011, after the death of the aquarium's only other orca. Marine animal activists say the transfers of orcas between marine parks are unhealthy for these mammals because of the stress and trauma. Hide Caption 6 of 8 Photos: Killer whales in captivity This female killer whale, Morgan, was taken in by a Dutch dolphinarium after being found starving in the shallow waters of the North Sea off the Netherlands coast. She is now performing at Loro Parque in Spain's Canary Islands -- despite an agreement that she would be released into the wild after her rehabilitation. Animal rights activists have mounted a legal challenge for her release. Hide Caption 7 of 8 Photos: Killer whales in captivity Today, there are 45 captive orcas performing at about 10 parks across the world, most of them born in captivity. Here, orcas perform at the Marineland aquatic park in Antibes, in southeastern France. Hide Caption 8 of 8

"The orcas will continue to live at SeaWorld for many years to come, inspiring guests in new and natural ways," the company said. "They will continue to receive the highest-quality care based on the latest advances in marine veterinary medicine, science and zoological best practices."