VALLEJO (CBS13) – Semo, the bottlenose dolphin at Six Flags Discovery Kingdom, passed away Tuesday at the age of 54.

Semo was the oldest known male bottlenose dolphin living under human care. The average life span for a dolphin under human care is 25 years. It’s 37 years or older in the wild.

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Credit: Six Flags Discovery Kingdom

The cause of death is more than likely old age; however, a necropsy will be performed.

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Credit: Six Flags Discovery Kingdom

“Semo was a ruggedly handsome, large and imposing male, who was also infinitely joyful and playful,” said Animal Care Director, Dianne Cameron. “We feel so fortunate to have been a part of his life.”

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Credit: Six Flags Discovery Kingdom

The dolphin came to live at Six Flags Discovery Kingdom in 2012 from the Minnesota Zoo. before that Semo lived at SeaWorld.