According to the Zoo, 21-year-old Flounder died in his sleep. Zoo officials say he was being treated for age-related joint pain at the time.

They say Flounder was the last surviving sea lion from the family group that once lived in the main building of the zoo.

Two other sea lions, both three years old, remain at the Rocky Coasts building.

The life expectancy of a sea lion is about 19 years.