Two grey whales have become stranded in shallow water off Delta's Centennial Beach in Boundary Bay, according to numerous media accounts on Friday afternoon (May 10).

CBC News reported on Twitter that Fisheries and Oceans Canada (FOC) is on the scene with a vessel and reflotation devices. The area where the whales—reportedly a mother and calf—are stranded appears crisscrossed with sandbars at low tide. Operators at an FOC after-hours number were unable to connect the Straight to a fisheries spokesperson.

Grey whales spend the winter off the west coast of Mexico, in Baja California, where calves are born and nourished until February or March, when they begin their annual migration north to Alaskan waters, where they feed in the Bering Sea and Arctic Ocean region during the summer and build up body fat for the return migration and winter.

The protected grey whale population has rebounded in recent decades from historical lows and are now considered abundant in the eastern Pacific Ocean, with a population fluctuating at about 20,000.

Mothers with calves usually leave last during this migration, and they are often seen in the spring off the coast of Oregon and Washington states, usually appearing off the west coast of Vancouver Island in May. Because these whales feed in bottom sediment, they travel relatively close to shore and are usually more visible than other whale species. This also makes them vulnerable to stranding in shallow waters in bays and near beaches.

Recent strandings of grey whales in California, Oregon, and Washington state (where 11 stranded in past weeks and 10 died) have concerned scientists, who have observed signs of emaciation in many of them.