Aurora, a 20-year-old Beluga whale, swims with her calf after giving birth at 3:39 p.m. PT Sunday at the Vancouver Aquarium. (Darryl Dyck/Canadian Press)

Aurora, the 20-year-old beluga grandmother at Vancouver Aquarium, gave birth to a calf Sunday afternoon.

Staff called it a thrilling event for the aquarium and although they couldn't conclusively comment on the calf's gender, they said it appears to be a female.

Visitors and volunteers gathered around the beluga habitat to watch the birth and, after a few false starts, the baby emerged to cheers from the crowd.

Sharon Newman has been haunting the aquarium since Aurora was put under 24-hour surveillance to monitor her condition.

"I'm a volunteer. I hang around here as much as I can because this is one of the most incredible things you'd ever see."

Newman said it's easy to see why so many people are fascinated by whales.

"They're mammals, they live in a different environment, they're so much like us and yet so different from us," she said.

Staff at the aquarium will monitor Aurora and the calf as they bond in their own pool for the next few days.

In preparation for Aurora's labour, Qila and Tiqa — her daughter and granddaughter — were temporarily separated from Aurora to allow her maximum space to give birth and to avoid any potential interference from the other animals.

"Aurora is an amazing beluga whale and holds a very special place in all our hearts," Martin Haulena, a veterinarian at the aquarium, said in a release before the birth.

"Aurora has proven herself to be an excellent mother and grandmother and she has a very experienced veterinary and marine mammal care team standing by and ready to assist if required."

Aquarium staff announced last Friday that Aurora was preparing to give birth.

Aurora's first calf, Qila, was born in 1995. She was the first calf to be conceived and born in a Canadian aquarium. Aurora's second calf, Tuvaq, was born in 2002 but died suddenly in 2005.

Qila gave birth to her own calf, Tiqa, in 2008.