The beluga inhabits a discontinuous circumpolar distribution in Arctic and sub-Arctic waters.
The beluga whale or white whale (Delphinapterus leucas) is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genus Delphinapterus. This marine mammal is commonly referred to simply as the melonhead, beluga or sea canary due to its high-pitched twitter. It is adapted to life in the Arctic, so has anatomical and physiological characteristics that differentiate it from other cetaceans. Amongst these are its unmistakable all-white colour and the absence of a dorsal fin. It possesses a distinctive protuberance at the front of its head which houses an echolocation organ called the melon, which in this species is large and plastic (deformable).
During the summer, they can mainly be found in the deep waters ranging from 76°N to 80°N, particularly along the coasts of Alaska, northern Canada, western Greenland, and northern Russia. The southernmost extent of their range includes isolated populations in the St. Lawrence River in the Atlantic, and the Amur River delta, the Shantar Islands, and the waters surrounding Sakhalin Island in the Sea of Okhotsk., and some regular migrations do occur into Russian EEZ of Sea of Japan such as to Rudnaya bay where diving with wild Belugas become a less known but popular attraction.
The species presents a moderate degree of sexual dimorphism, as the males are 25% longer than the females and are sturdier. Adult male belugas can range from 3.5 to 5.5 m (11 to 18 ft), while the females measure 3 to 4.1 m (9.8 to 13.5 ft). Males weigh between 1,100 and 1,600 kg (2,400 and 3,500 lb), occasionally up to 1,900 kg (4,200 lb) while females weigh between 700 and 1,200 kg (1,500 and 2,600 lb). They rank as mid-sized species among toothed whales.
They are opportunistic feeders; their feeding habits depend on their locations and the season. In general, the diets of these cetaceans consist mainly of fish; apart from those previously mentioned, other fish they feed on include capelin (Mallotus villosus), smelt, sole, flounder, herring, sculpin and other types of salmon. They also consume a great quantity of invertebrates, apart from shrimp, such as squid, crabs, clams, octopus, sea snails, bristle worms and other deep-sea species. Animals in captivity eat 2.5% to 3% of their body weight per day, which equates to 18.2 to 27.2 kg.
Female belugas typically give birth to one calf every three years. Most mating occurs usually February through May, but some mating occurs at other times of year. Newborns are able to swim alongside their mothers immediately after birth. The newborn calves nurse under water and initiate lactation a few hours after birth; thereafter, they feed at intervals of around an hour. The calves remain dependent on their mothers for nursing for the first year, when their teeth appear. After this, they start to supplement their diets with shrimps and small fish. The majority of the calves continue nursing until they are 20 months old.
These cetaceans are highly sociable and they regularly form small groups, or pods, that may contain between two and 25 individuals, with an average of 10 members. They are cooperative animals and frequently hunt in coordinated groups. The animals in a pod are very sociable and often chase each other as if they are playing or fighting, and they often rub up against each other. In captivity, they can be seen to be constantly playing, vocalizing and swimming around each other. Belugas also show a great degree of curiosity towards humans in the wild, and frequently swim alongside boats.