PORTLAND, Ore. (KOIN) – The Oregon Coast Aquarium’s 9-year-old male sea otter Nuka died on Tuesday after undergoing an emergency operation.

“The Oregon Coast Aquarium is saddened to announce the passing of Nuka, the Aquarium’s resident northern sea otter,” the aquarium said. “Nuka passed following an emergency veterinary procedure, which was carried out after staff observed atypical behavior and physical symptoms.”

The otter’s cause of death is unknown at this time. A full necropsy is planned to learn what caused Nuka’s untimely passing.

In the wild, sea otters typically live into their early to mid-teens, the aquarium said. In captivity, they can live into their late teens or early twenties.

Nuka was brought to the aquarium as a pup in February of 2014, seven months after he was found stranded on a beach in Kodiak, Alaska. His name means “younger sibling” in the Inuit language.

“Severely malnourished and only three months old, he was taken to Alaska SeaLife Center for care, and was subsequently deemed non-releasable,” the Oregon Coast Aquarium said.

Weighing between 60 and 70 pounds, Nuka was the largest of the Aquarium’s sea otters. Nuka’s caretakers described him as a slow eater who savored every piece of shrimp.

“Despite his size, he never claimed the role of dominant otter, and was known for his relaxed attitude,” the aquarium said. 

Oregon Coast Aquarium Curator of Marine Mammals Brittany Blades said that Nuka was also known for wrapping himself in kelp strips and sleeping on top of a rock in the center of the habitat for everyone to see.

“We will all miss him so much,” Blades said.

Nuka leaves behind his fellow aquarium otters Oswald, Schuster and Earle.