NIAGARA FALLS, ON. – Kiska, an orca at Marineland and the last captive in Canada to swim alone in her tank for more than a decade, has died.

The Ontario government said it was notified of his death by Marineland Park in Niagara Falls on Thursday.

Animal welfare officials were at the park on Friday when Marineland performed an autopsy on the animal, a spokesman for the attorney general’s office said.

Marineland owner Marie Holer declined to comment on Kiska’s death when reached by phone from The Canadian Press.

The park told the Niagara Falls Review that the orca’s health has recently deteriorated “despite intensive interventions from its caretakers, Marineland’s veterinary team and international veterinarians with experience supporting whale health and welfare.”

Kiska would be 47 years old and had lived in Marineland since her capture in Icelandic waters in 1979.

She was captured along with Keiko, who rose to fame in the movie My Friend Willy, and the duo lived together in Marineland for a number of years in the 1980s. Keiko was sold to an aquarium in Mexico in 1985 and moved to where she eventually was found at SeaWorld.

Kiska has been performing shows at Marineland for years, but it’s been over a decade since her last appearance. She spent that time in a large pool at Friendship Cove, separated from a pod of beluga whales.

Kiska gave birth to five cubs during her time at Marineland, but they all died young.

The group Humane Canada released a statement saying it was saddened and outraged by the death of Kiska, “the world’s loneliest orca.”

“This news is heartbreaking for everyone who has campaigned for his release for years,” the group said.