A two-year-old Steller sea lion born and raised at the Alaska SeaLife Center (ASLC) in Seward died unexpectedly in late January. The cause of death is still undetermined.
ASLC officials said the Steller sea lion, Mist, experienced seizure-like tremors and passed away within minutes of the episode on Jan. 23.
The incident occurred while Mist and three other Steller sea lions were socializing in a new group setting. In order to mimic natural and social behaviors in the wild, these groupings change regularly at ASLC and staff always monitor the animals. Introductions went well and the annual care staff noted play and normal social behaviors throughout the morning.
Mist’s seizure-like tremors began suddenly, and staff responded immediately. The other Steller sea lions were shifted to another habitat so veterinary staff could tend to Mist, but she was unresponsive.
A necropsy was performed the following day, with no immediate findings of what caused the tremors. Additional tissue samples were collected, and it could take several weeks for those samples to be analyzed, but tests may never reveal the cause of death, ASLC staff said.
Mist was born on June 26, 2020, to ASLC Steller sea lions Mara and Pilot. She was Mara’s first pup and the fifth Steller sea lion birth at ASLC.
Steller sea lions are the largest member of the eared seal family. The species ranges across the northern Pacific Ocean, from Japan through the Aleutian Islands and southeast Alaska to northern California. Divided into eastern and western regions, the western population is currently listed as endangered, while the eastern population was delisted in 2013 following notable recovery and significant conservation efforts.
