Beluga

Belugas have a round and muscular body that is tapered at both ends. The tapering begins at the base of its neck, which gives the beluga the appearance of shoulders. This trait is unique compared to other cetaceans. Beluga whales do not have fused neck vertebrae. The neck of a beluga is narrower when compared to other extant whales. The unusual vertebrae traits in a beluga allow it to move its head and nod.

The beluga inhabits a discontinuous circumpolar distribution in Arctic and sub-Arctic waters. During the summer, they can mainly be found in 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.

Belugas play an important role in the structure and function of marine resources in the Arctic Ocean, as they are the most abundant toothed whales in the region. They are opportunistic feeders; their feeding habits depend on their locations and the season. For example, when they are in the Beaufort Sea, they mainly eat polar cod (Boreogadus saida) and the stomachs of belugas caught near Greenland were found to contain rose fish (Sebastes marinus), Greenland halibut (Reinhardtius hippoglossoides) and northern shrimp (Pandalus borealis), while in Alaska their staple diet is Coho salmon (Oncorhynchus kisutch). In general, the diets of these cetaceans consist mainly of fish; apart from those previously mentioned, other fish they feed on include herring, capelin, smelt, cod, salmon, flatfish, sculpin, lingcod, and eulachon.

Belugas 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. Pods tend to be unstable, meaning individuals tend to move from pod to pod. Radio tracking has even shown belugas can start out in one pod and within a few days be hundreds of miles away from that pod. Beluga whale pods can be grouped into three categories: nurseries (which consist of mother and calves), bachelors (which consist of all males), and mixed groups (which contain both sexes). Most beluga whale pods were not organized primarily around close maternal relatives; the pods included both relatives and non-relatives, many members were paternal rather than maternal relatives, and there were also many cases where unrelated adult males traveled together.

Estimations of the age of sexual maturity for beluga whales vary considerably; the majority of authors estimate males reach sexual maturity when they are between nine and fifteen years old, and females reach maturity between eight and fourteen years old. The average age at which females first give birth is 8.5 years and fertility begins to decrease when they are 25, eventually undergoing menopause, and ceasing reproductive potential with no births recorded for females older than 41. There is a slight difference on the sexual maturation period between males and females. The male beluga whales take seven to nine years to become sexually mature, while the females take four to seven years.

The native populations of the Arctic in Alaska, Canada, Greenland and Russia hunt belugas, for both consumption and profit. Belugas have been easy prey for hunters due to their predictable migration patterns and the high population density in estuaries and surrounding coastal areas during the summer.