The Oregon Coast Aquarium reports the passing of Nuka, the Aquarium’s resident northern sea otter.

Nuka passed following an emergency veterinary procedure, which was carried out after staff observed atypical behavior and physical symptoms, the Aquarium said.

The exact cause of Nuka’s passing is unknown at this time, the Aquarium stated. A full necropsy will be performed to gain further insight.

Nuka was just shy of turning 10 years old. Nuka was originally found stranded on a beach in Kodiak, Alaska, in June 2013. Severely malnourished and only three months old, he was taken to Alaska SeaLife Center for care, and was subsequently deemed non-releasable. He came to his forever home at the Aquarium in February 2014.

While the name Nuka means younger sibling in the Inuit language, he was the largest of the Aquarium’s sea otter raft, weighing between 60 and 70 pounds. Despite his size, he never claimed the role of dominant otter, and was known for his relaxed attitude, according to the Aquarium.

Nuka acted as an ambassador of his species, fostering connections between Aquarium visitors and marine wildlife; his loss is felt throughout the Aquarium and beyond.

“Nuka was our largest sea otter, and the easiest for our guests to identify,” said OCAq Curator of Marine Mammals Brittany Blades, who worked with Nuka since his arrival to the Aquarium. “He enjoyed wrapping himself in kelp strips and sleeping atop a rock in the center of the habitat for everyone to see. We will all miss him so much.”