A day after a beluga whale died suddenly at the Vancouver Aquarium, a second beluga has fallen ill.

The Vancouver Aquarium said Thursday Qila's mother Aurora is experiencing the same symptoms as Qila did before she died Wednesday morning.

Aquarium president John Nightingale told a news conference Thursday the 29-year-old beluga is showing signs of abdominal discomfort and hasn't eaten in two days.

Nightingale says Aurora is isolated in a medical tank and under 24-hour watch.

"Aurora is our priority right now. We are incredibly concerned," he said.

Aurora the beluga whale is tended to by Vancouver Aquarium officials on Nov. 18, 2016. (Vancouver Aquarium)

Cause of death inconclusive

The death of 21-year-old Qila was sudden and unexpected, said aquarium veterinarian Martin Haulena.

Haulena said the necropsy performed Wednesday was inconclusive as to cause of death but samples have been sent to specialists "around the world" and more tests are being completed.

Test results found a large but "walled off" abscess on Qila's lung but it's not clear if that contributed to her death. Blood tests conducted prior to the whale's death came back normal.\

The death of 21-year-old Qila was sudden and unexpected, the aquarium's president and CEO John Nightingale told a news conference Thursday. (Darryl Dyck/The Canadian Press)

Haulena said staff first noticed Qila had been "off" last week.

They became concerned when they noticed she had decreased her food intake and began monitoring her.

Haulena said Qila's condition appeared to be improving Tuesday evening as she interacted with trainers.

But then she stopped eating completely in the 24 hours prior to her death.

Aquarium staff 'shell shocked'

Nightingale teared up briefly at the news conference, saying Vancouver Aquarium staff are "shell-shocked" by the developments.

"In 30 years of working in aquariums, never have I been so affected by the death of an animal," he said.

He said that while Aurora is aware that Qila has died, they do not know how beluga whales feel or process grief.

Vancouver Aquarium officials examine the beluga Aurora on Nov. 18, 2016. (Vancouver Aquarium)

Family history

Qila, the first beluga whale conceived and born in a Canadian aquarium, was Aurora's first offspring.

Aurora's second calf Tuvaq, a male, was born in 2002 and died in 2005. Her third calf, a female named Nala, was born in 2009 but died a year later from an apparent infection.

Qila became a mother in June 2008 when she gave birth to a female calf named Tiqa, who died three years later of pneumonia.

With files from the Canadian Press