The National Aquarium says its oldest Atlantic bottlenose dolphin has died.
The aquarium said in a statement Tuesday that 44-year-old Nani exhibited unusual behavior on Monday and died that evening despite emergency care from the animal care team. The aquarium says they are trying to determine the cause of her death.
Nani, who was born in the wild, was the matriarch of the aquarium's colony. She came to Baltimore in 1990 from another institution that closed.
The aquarium is still home to seven other Atlantic bottlenose dolphins, including Nani's children, Beau and Spirit.
The aquarium plans to create the first North American dolphin sanctuary in Florida or the Caribbean, which is set to open in 2020.