For several anxious hours Friday, marine biologists with the Department of Fisheries and Oceans looked on as a grey whale and her calf struggled to free themselves from a sandbar in the shallow waters of Boundary Bay.

Local resident Stefan Geffke notified the DFO after spotting the stranded mammals around 2:30 in the afternoon.

“I could hear the sound of the whales, like the blowholes,” he said. “I could kind of see them and I was the only one out there so I walked out, probably, to the marker, which is over a kilometre out, and from there I could see they were struggling.”

Over the next few hours, DFO staff monitored the whales from a boat, as dozens of spectators descended on the beach to get a look for themselves.

Paul Cotrell, a DFO marine mammal coordinator, said biologists decided not to attempt to assist the mother and calf with flotation devices because working with the two stranded animals so close together could have been dangerous for rescuers.

In the early evening, the incoming tide floated the two massive mammals, and they were able to move again.

Initially disoriented, the whales eventually swam out towards deeper water with a little guidance from a DFO boat.

"They were acting like normal grey whales again," Cotrell told CTV News.

Stranded grey whales not uncommon

Martin Haulena, the head veterinarian with the Vancouver Aquarium’s Marine Mammal Rescue Team, was on standby to lend a hand, but his services were not needed Friday.

He said grey whales are bottom feeders and this pair likely swam into Boundary Bay to forage for food in the muddy shallows when they got in trouble.

"This is incredibly long, flat beach,” said Haulena. “But that geography is very bad for whales. It can make them get caught very easily.”

Although the animals managed to swim away without any assistance, their time on the beach could still have lasting health impacts.

"When they come on land, they start to bear weight when they were never supposed to bear weight,” said Haulena. “That mass compresses the lungs, they can't breathe correctly. It compresses circulation. Kidneys start to die, muscles start to die. Those organs start releasing toxins."

DFO biologists in a boat followed the whales for about three hours after they left the bay and say they eventually began to exhibit normal behaviour again.

Cotrell said the DFO will continue to try to track the whales for the foreseeable future to monitor them for any long-term health impacts.

He said the DFO usually responds to a handful of similiar rescues every year in B.C. waters.

With files from CTV Vancouver's Angela Jung