Mist, a Steller sea lion at Alaska SeaLife Center, passed away unexpectedly Jan. 23, following seizure-like tremors.

The center announced her death in a release Monday, saying that the cause of death was unclear, even following a necropsy.

Mist, who was approximately 2-and-a-half years old, had been socializing with three other Steller sea lions at the center. The release explained that sea lion groupings are often changed to “mimic natural and social behaviors in the wild.”

Mist had been successfully introduced to the group, and play and behavior was viewed as normal by staff. The tremors reportedly came on suddenly, “and seemed unprompted.”

The release said that as a result of close monitoring because of the new group setting, a mammalogist noticed and responded immediately. The other sea lions were shifted to another habitat.

“Though these staff arrived within minutes, Mist had unfortunately already become unresponsive,” the release said.

As part of the necropsy, tissue samples were collected to be analyzed, but the release said that it may be several weeks before results are received, and that they may fail to reveal a cause of death.

The release said that Mist was born in June of 2020 to two sea lions within the center, Mara and Pilot. She was the first successful pup borne by Mara, and the fifth successful birth of a Steller sea lion in center history.

“Mist was an animal who touched you immediately with her playful, clever, gregarious personality, and she was quickly a favorite for staff and guests alike. She was a bubbling force of energy and inquisitiveness with a nearly unrivaled level of potential, possessing a balance of intelligence, patience, and cleverness that was uniquely amazing to behold in one individual,” said Michelle Hanenburg, SeaLife mammal curator, in the release.

According to the release, the Alaska SeaLife Center is one of only three aquariums in North America that house Steller sea lions.

For more information about the Alaska SeaLife Center, visit alaskasealife.org.

Reach reporter Jake Dye at jacob.dye@peninsulaclarion.com.

Alaska SeaLife Center Mammalogist Shelby Burman participates in a training session with Mist the Steller sea lion at the Alaska SeaLife Center on Jan. 19, 2023. Mist passed away unexpectedly on Jan. 23 after ASLC animal care staff observed seizure-like tremors. (Photo courtesy Kaiti Grant/Alaska SeaLife Center)