MYSTIC, Conn. (AP) — Mystic Aquarium says and endangered Steller sea lion has died in the top tourist attraction in southeastern Connecticut.

The male sea lion named Kodiak was euthanized Friday after not responding to treatment of liver disease and kidney failure. He was about 15 years old.

The Aquarium says experts put down the marine mammal after efforts by its animal care team and other specialists nationwide failed to treat him.

A necropsy will be performed in an effort to learn more about his illness.

Kodiak came to Mystic Aquarium from Vancouver Aquarium in 2002. At 2,000 pounds, he was a tremendous ambassador to his species and a favorite among Mystic Aquarium guests for his size and exuberant personality.

Steller sea lions are protected under the Endangered Species Act.