The mammal care team at Marineland is in mourning following the loss of Sonja the Walrus.
Sonja passed suddenly late Thursday, May, 25, 2017, after the park was closed.
Though she was under the care of a vet for symptoms of an unknown illness, her death was unexpected.
Sonja joined Marineland in 2004, with a news release stating she ''lived a life full of enrichment" and that she "thrived in her home at Marineland."
The park's remaining walruses continue to be monitored but are showing no concerning medical issues.
An autopsy has been conducted and results are expected within the next two weeks.
A full medical report will be be provided to the Animal Care Committee due to new strict Ontario Marine Mammal Care regulations.