SAN ANTONIO (AP) — A newborn beluga whale born prematurely at SeaWorld San Antonio has died.

A SeaWorld statement says the 3-week-old calf died Sunday despite what park officials called “round the clock” care by park staff since the calf’s birth June 20 one month prematurely.

Park veterinarians grew concerned that the calf wouldn’t gain weight as rapidly as expected, so marine mammal infant formula was given seven times a day on top of nursing from the calf’s mother.

A necropsy was performed on the calf Monday to determine the cause of death. Results are expected in about eight weeks.