Summer refuge: Beluga whales bustle in the Hudson Bay

For more than seven months between November and June, the Hudson Bay in northern Canada is frozen over. But every year, as soon as the sea ice melts, some 55,000 beluga whales migrate from the Arctic to the bay, in order to give birth to their offspring in relatively warm temperatures. The bay's beluga whale population is the largest in the world.

Beluga calves are dependent upon their mothers for up to two years. They're mostly raised in the icy waters surrounding Greenland, northern Canada, northern Norway and northern Russia. Calves are usually gray whereas adults are white. Belugas grow up to 6 meters (20 ft) and usually live to be 40 to 60 years old.

An underwater view of a young beluga calf, swimming with its mother near the mouth of the Churchill River in the Hudson Bay. The playful animals with the childlike smile often approach humans with curiosity while sliding through the water in pods and communicating in their own language of sounds, to the amazement of tourists who travel to Canada to watch belugas and other whales.

Beluga whales can produce up to 50 different sounds. Due to their various whistles, clicks, chirps, and squeals, they have been nicknamed "canaries of the sea." "Belugas are sound-centered species, and sound to them is really like vision to us," Valeria Vergara, a researcher with the Raincoast Conservation Foundation, told the AFP news agency.

The Inuit refer to the summer months, during which the whales advance from the Arctic to the bays and fjords located further south, as "the great migration." Beluga whales are of major importance to Canada's indigenous people, both culturally and as a food source. This mural in the small town of Churchill honors the relationship between humans and animals.

Although Hudson Bay offers them protection from orcas, beluga whales face other dangers as well, like hunting polar bears. However, a man-made problem is of more concern to animal researchers and conservationists: The loss of sea ice due to climate change. This poses a threat to local wildlife.

The sea mammals are also facing other man-made dangers. At a size of 1.23 million square kilometers (500,000 square miles), the Hudson Bay is a gigantic area but it is also heavily contaminated with environmental toxins. This affects the belugas as well: Increasingly, whales have been found to suffer from cancer and skin diseases.