Whale of the Month - Beluga Whale

Species fact file

Common names: beluga whale, white whale

Icelandic name: mjaldur, hvíthvalur

Scientific name: Delphinapterus leucas

Family: Monodontidae (narwhal and beluga)

Max length: 4m (females), 5.5m (males)

Distribution: Arctic and sub-arctic

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Beluga whales are one of only three species of cetacean native to the Arctic. Together with narwhals, another Arctic specialist, they make up the Monodontid family.

The most distinctive characteristic of this species is their colour. Their name is derived from the Russian word for white, and they are known as the white whale in many languages. But belugas are actually born dark grey, and become white as they age. Calves begin to lose their pigmentation when they are about one month old – it can take more than 10 years until they are fully white!

Belugas are superbly adapted to life in frozen seas, and they need to be - some belugas have been recorded travelling several hundred kilometres into dense sea ice. They have a thick layer of blubber, which can make up almost 50% of their body weight, and a proportionately small head and fins to reduce heat loss. Belugas, like many polar cetaceans, have no dorsal fin: this is probably also a way to reduce heat loss, as well as an adaptation to swimming underneath the ice sheet.

Some beluga populations have a fixed range, and stay in the same region year-round. Others migrate seasonally between different parts of the Arctic. Their migration is closely linked to the sea ice: in winter, most belugas travel with the advancing ice edge, and when the ice begins to recede in spring they move into their coastal summer grounds. However, some populations spend the whole winter in iced-over areas of the Arctic. So far from open ocean, their survival here relies entirely on holes and cracks in the ice sheet (called ‘polynyas’ and ‘leads’) remaining open until the spring. Recent research suggests that they might use sound while diving to find the openings in the ice sheet that they need to breathe.

During the summer months, beluga whales congregate in groups of hundreds or thousands in shallow bays, coastal inlets, and river estuaries. These areas are the safest place for young calves – here, they are sheltered from the worst of the Arctic conditions, and are probably less vulnerable to killer whales.  

Belugas are the only cetacean to have a regular moult; this is another important reason why they gather in these particular locations over summer. Their summering grounds have relatively warm water, usually with some freshwater input, and a gravelly bottom – these conditions are thought to be ideal for moulting. The belugas rub themselves against the gravel to help get rid of old, tough skin, and the warm, low-salinity water helps to stimulate the growth of new skin.  

Belugas are a highly sociable species: they live in pods, which are typically made up of about 10 whales but can be as large as 25. Pod membership is very fluid and belugas like to move around from one group to another, sometimes spending just a few days with one pod before joining another. Engaging in social behaviour seems to be really important to belugas, and they spend a lot of time playing with and seeking out physical contact with other individuals in their pod.

Their diet is mostly fish, but beluga whales are opportunistic predators and will hunt whatever is most abundant, depending on season and location. Common prey species include cod, halibut, salmon, capelin, herring, flounder and sole. Belugas do also feed on invertebrates such as shrimp, crab, lobster, and cephalopods. They generally don’t dive very deep while hunting, although some belugas have been recorded reaching depths of 1000m or more.

Beluga whales are among the most vocal of all cetaceans – their repertoire includes over 50 call types which they use to communicate with one another. Their high frequency whistles sound like birdsong, which has earned them the nickname ‘canaries of the sea’.  

Climate change poses a major threat to belugas. Their seasonal migrations are tied to the annual cycle of sea ice formation. It’s very hard to predict how changes in sea ice extent will affect beluga whales, but we are already seeing some beluga populations begin to occupy different areas of the Arctic. Sea ice is also a critical habitat for many of their prey species, and provides protection against killer whales. With a reduction in ice coverage, killer whales are now able to reach parts of the Arctic where belugas were previously safe.

Because belugas have quite flexible diet and habitat preferences, they are probably more likely to weather changes in their environment than many other cetaceans. Currently, the species is classed as Least Concern on the IUCN Red List – however, certain populations of beluga whales are critically endangered.

Some of the highest contamination levels of any cetacean have been recorded in beluga whales. Due to a combination of several ecological and oceanographical factors, arctic animals are particularly susceptible to contamination. Belugas that are found in areas of high human population are highly contaminated by both chemical pollutants and heavy metals – so much so that when they die, the bodies have to be treated as toxic waste. This could have serious repercussions for the species; not only are these pollutants carcinogenic, but they suppress the immune system and prevent reproduction which may hinder an endangered population’s ability to recover in the face of other threats.

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Learn more about...

Using satellite tags to track beluga migrations through sea ice

Chemical and heavy metal contamination in beluga whales