Sean Rossman

USA TODAY

One of SeaWorld's better-known orcas, Tilikum, perhaps best known for killing his trainer in 2010, died early Friday morning.

SeaWorld said he died surrounded by trainers, care staff and veterinarians. A cause of death is yet to be determined and a necropsy is planned. However, the organization said he had faced "very serious health issues" and veterinarians had been treating him for a "persistent and complicated bacterial lung infection."

Tilikum, SeaWorld said, was estimated to be 36 years old, a little older than the orcas, commonly known as "killer whales," who live in the region where he originated. He came to SeaWorld in 1991 from Sealand of the Pacific in Canada.

In February 2010, Tilikum was interacting with his trainer, 40-year-old Dawn Brancheau, at SeaWorld Orlando's Shamu Stadium when he grabbed her by the ponytail and pulled her underwater as a horrified audience looked on.

A medical examiner determined Brancheau's death was accidental, saying she died of drowning and traumatic injuries.

The incident sparked a backlash against SeaWorld and inspired the movie "Blackfish," which questioned the ethics of orcas in captivity.

SeaWorld recognized Brancheau in a blog post about Tilikum, saying the killer whale will be "inextricably connected" to her death. After the incident, SeaWorld continued to allow Tilikum, who weighed 12,000 pounds, to mix and mate with the rest of the orcas.

"While we all experienced profound sadness about that loss, we continued to offer Tilikum the best care possible, each and every day," the post said.

SeaWorld's's President and CEO Joel Manby expressed his condolences.

"Tilikum had, and will continue to have, a special place in the hearts of the SeaWorld family, as well as the millions of people all over the world that he inspired," Manby said. "My heart goes out to our team who cared for him like family."

The People for the Ethical Treatment of Animals (PETA), one of SeaWorld's critics following the death of Brancheau, tweeted a photo Friday morning that read, "R.I.P. Tilikum. Dead after three decades of misery."

Tillikum's death means 22 SeaWorld orcas remain at facilities in Orlando, San Antonio and San Diego. The company announced the current generation of Orcas would be the last at SeaWorld, which will stop breeding them. The company also said it would tweak the orcas' performances moving forward to more reflect their natural habitat and behaviors. SeaWorld has not housed a whale from the wild in almost 40 years.

PETA Senior Vice President Lisa Lange said the end of the program came too late for Tilikum. She said his life was tragic and filled with pain, adding he was bred 21 times with 11 of his children dying before him.

"SeaWorld needs to release all the remaining animals from its parks – the orcas, beluga whales, bottlenose dolphins, sea lions, walruses, penguins and others — and rehabilitate them back into nature or into coastal sanctuaries where they can spend the rest of their lives in as natural a setting as possible," Lange said in a statement.

The rest of the whales, SeaWorld said, are behaving normally after Tilikum's death.

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