Semo, the oldest male bottlenose dolphin in the United States, died at the age of 54 at Six Flags Discovery Kingdom in Vallejo on Tuesday. He appeared to have died of natural causes but a necropsy is planned.
A fan favorite at Discovery Kingdom, Semo was formerly at the Minnesota Zoo and SeaWorld in San Diego. He came to Vallejo in 2014. To keep him mentally and physically stimulated, he participated in the park’s Dolphin Discovery educational program and quickly won over new fans.
The average dolphin life span is 25 years in captivity and 12 years or more in the wild, making Semo very old even in captivity. Discovery Kingdom is known for its care of elderly dolphins, currently holding multiple in their 30’s.