A popular dolphin died at the Vancouver Aquarium early Thursday morning, following a prolonged illness.

"Spinnaker has been taken to the provincial animal health centre where Dr. Haulena is conducting a full necropsy today. We expect to have preliminary necropsy results on Friday."

"Spinnaker had been under close observation for several months with a prolonged illness," said a statement released by the aquarium on Thursday morning.

"Under the care and supervision of the aquarium’s veterinarian Dr. Martin Haulena, Spinnaker had been receiving treatment and appeared to be doing better in recent weeks."

Spinnaker was a popular attraction at the Vancouver Aquarium in Stanley Park. (Vancouver Aquarium)

The male dolphin, which was estimated to be at least 25 years old, was one of three Pacific white-sided dolphins rescued from fishing nets that were living at the aquarium in Stanley Park. The remaining two are Hana, a 14-year-old female, and Helen, a 21-year-old female.

The last dolphin to die at the aquarium was Laverne, a 31-year-old female, who died in 2009. The aquarium also has three beluga whales.

Other deaths at the aquarium in recent years include:

• In January, Milo, a 12-year-old sea otter, was euthanized after a battle with cancer.
• In September 2011, Tiqa, a beluga, died of pneumonia.
• In June 2010, a beluga calf named Nala died of a blocked airway.