Marineland's male sea lion Rufus has died, just one week short of his eighth birthday.
Born in Marineland, he died on Sunday while being transferred to Massey University for medical assessment after showing signs of being unwell on Friday.
The decision to transfer him to Palmerston North was made on advice of Marineland's vet.
Neil Fergus, manager of tourism services for Napier City Council, said Rufus was a much-loved animal "that certainly had a few character traits about him".
An autopsy of Rufus is under way at Massey University.
Rufus was named by then 10-year-old Gabby Parsons of Napier in 2005 after she won a competition, but she was not allowed to get close to Rufus due to his protective mother, Cody.
California sea lions are well known for their intelligence and are popular in marine parks because they are easily trained with a pleasant disposition.
Their life expectancy is about 17 years but they can live much longer in captivity.