They do not have a dorsal fin. Instead, along the back just behind the midpoint there is a narrow ridge notched laterally to form a series of small bumps. These ridges may be clearly visible on a swimming animal.
Newborn belugas are brown. As they age, they gradually lighten through slate gray, and by their sixth or seventh year have assumed the all-white coloration characteristic of adult animals.
Natural History Notes
Belugas feed on a variety of fishes (including cod and capelin), on squid, and on a variety of benthic crustaceans.
They are frequently found in shallow bays and river mouths, where the young are born, and occasionally ascend rivers.
May Be Confused With
Because of their limited distribution, all-white coloration and lack of a dorsal fin, belugas are unlikely to be confused with any other species of cetacean.
Distribution
Belugas have been reported from the Arctic Circle south as far as eastern Connecticut, typically in estuarine habitats, though they do range into oceanic regions. They are most abundant from the north shore of the Gulf of St. Lawrence northward. They remain near the Arctic Circle and in Hudson Bay to northern Greenland during winter, undertaking migrations to the south in autumn, straggling to the Maritime Provinces and as far as Connecticut. Belugas are regularly seen in the St. Lawrence and Saguenay rivers throughout late spring and summer. Return migrations to the north take place in spring.
A small population in the estuary of St. Lawrence is resident throughout the year.