Tilikum, the orca featured heavily in Gabriela Cowperthwaite’s documentary “Blackfish,” died Friday morning after 25 years of living at SeaWorld.

SeaWorld announced Friday that the whale, believed to be 36, passed away early in the morning after months of deteriorating health. SeaWorld veterinarians believe the cause of death was a persistent and complicated bacterial lung infection, though a necropsy will be performed to confirm. He had been fighting the illness since March.

In a statement, SeaWorld’s president and CEO Joel Manby said, “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. My heart goes out to our team who cared for him like family.”

In 1982, a fishing net captured Tilikum in Iceland. He spent the next few years in a zoo in Reykjavik and at the Sealand of the Pacific public aquarium in British Columbia. In 1992, SeaWorld acquired Tilikum and began to use him to breed killer whales. He’s since sired 21 calves. Tilikum’s transfer to SeaWorld Orlando occurred following the death of a young marine biology student who was killed by Tilikum and his two female companions. Sealand of the Pacific closed shortly after the fatalities. After his transfer, Tilikum killed two others while at SeaWorld.

Tilikum and the “Blackfish” documentary caused a stir when the film premiered in 2013. The scandal, stemming from the alleged stress placed on orcas in captivity and Tilikum’s role in the human deaths, caused SeaWorld to roll back its orca program. In November, SeaWorld announced plans to end killer-whale shows. In March, three years after the film’s release, the theme park announced it would further cut down orca involvement at SeaWorld by ending its breeding program and phasing out all live performances using the animals.

In the wake of the film, which was nominated for a BAFTA Award, dozens of celebrities condemned SeaWorld for its treatment of killer whales, an apex predator in most of the world’s oceans. Some, including the Beach Boys, Willie Nelson and Heart, even went so far as to cancel performances at SeaWorld-sponsored events. The backlash also is thought to be responsible for financial loss to the park in the months following.