The snow-white beluga whale is one of the most distinctive of all cetaceans (a group that includes dolphins, whales and porpoises). The stocky body ends in a particularly small head, and adults develop their striking white colouring as they mature. Beluga whales lack a dorsal fin; their genus name Delphinapterus means 'dolphin-without-a-wing', but there is a ridge of toughened skin along the back that tends to be more pronounced in mature males.
Unlike most cetaceans, beluga whales have an extremely flexible neck and can turn their head almost 90 degrees to the side. Their lips are also flexible and can form a variety of facial expressions. They have a very thick layer of blubber which may be up to 15 centimetres thick that provides insulation in the freezing arctic waters.
Beluga whales use a wide range of vocalisations such as clicks, grunts, squeals, screeches and whistles. These sounds can be heard through the hulls of ships and the beluga whale was nicknamed the 'sea canary' by early Arctic sailors.
Range
Beluga whales are found in Arctic waters around northern Russia, North America, Greenland and the Norwegian archipelago of Svalbard. Most populations migrate north in the spring, then south in the autumn once ice starts to form
Habitat
The beluga whale inhabits cold arctic waters, usually near to the ice edge. Summer is spent in shallow bays and estuaries, whereas in winter, the beluga whale occurs in areas of loose pack ice, where wind and ocean currents keep cracks for breathing holes open.
Biology
The beluga whale is a highly social animal, and in the summer months thousands of individuals can be seen gathered in estuaries. At this time, females with calves will often come together, whilst males form large bachelor groups. Also, in summer months, large numbers of beluga whales gather in estuaries to moult. They rub themselves on the gravel bed and shed the yellow, withered skin of the previous year to once again become gleaming white.
Beluga whales are able to dive to depths of over 1,000 metres, but spend most of their time on the surface of the water swimming slowly. During winter months it may be necessary for individuals to create breathing holes in the ice, which they can do with their heavy head. The flippers are capable of a wide-range of movement and enable the beluga whale to manoeuvre effectively.
The beluga whale feeds on a wide variety of fish, bottom-dwelling invertebrates and worms. Most of the prey is found on the seabed and it is thought that the highly flexible lips may be used to suck prey into the mouth. Sounds can be used to detect prey; the enlarged melon is an electro-receptor for sounds that are sent out from the nasal passages. Killer whales and polar bears are major predators of beluga whales, which are particularly vulnerable if trapped by ice.
Female beluga whales become sexually mature at around five years of age, and they give birth to a single calf after a gestation period that lasts just over a year. Mother and calf have an extremely strong bond, swimming very closely together, and the calf will continue to feed on its mother’s milk until well into its second year. These whales are thought to live for up to 50 years.
Threat
Beluga whales have traditionally been hunted for their blubber for many centuries, but only with the advent of commercial whaling did the harvest become unsustainable. This species is particularly vulnerable to such exploitation, due to its high fidelity for certain migratory routes.
However, perhaps the most pertinent threat to the beluga whale today is habitat deterioration in the form of industrial development and pollution of coastal habitats. Some beluga whale populations are declining principally as a result of pollution. Beluga whales in the St Lawrence River Estuary, for example, accumulate so many toxins that deformed calves are now prevalent and dead individuals are treated as toxic waste.
A further identified threat to the beluga whale is global climate change. While this species is not thought to be directly threatened by changes in weather patterns or global warming, reductions in sea ice cover will provide access to the Arctic for ships and other vessels, which were previously absent from the region. Formerly pristine areas that have long served as refuges for the beluga whale will become more navigable, with numbers of vessel sailing through the Arctic for gas and oil exploration, commercial shipping and fishing increasing. With the increase in ship traffic, ship strikes are likely to become an increasingly significant cause of beluga whale injury and death.
In addition, beluga whales detect and respond to the presence of large ships over great distances of up to 50 kilometres. Industrial noise, for example from ships, seismic surveys and offshore drilling, likely disrupts beluga whale behaviour and may impair their ability to communicate and forage efficiently. Industrialisation and urbanisation of the Arctic is also bound to exacerbate the problem of pollution.
Climate change is also likely to lead to a loss of sea ice and increased ocean temperatures. This may affect the distribution, composition and productivity of beluga whale prey species, affecting the beluga whale’s ability to find prey. Furthermore, as weather patterns become more unpredictable and extreme, it is possible that the beluga whale will become more susceptible to ice entrapment. Such unfortunate events have always occurred, but it is feared that the frequency and scale of the mortality from ice entrapment will increase as the climate changes.
Conservation
Today the widespread hunting of beluga whales is prohibited under the International Moratorium on Commercial Whaling; however, small quotas are permitted to local people who depend upon annual harvests for food. The Alaska and Inuvialuit Beluga Whale Committee was established in 1988 and encourages dialogue between native hunters, conservationists and government representatives as well as carrying out stock and hunting assessment of the Alaskan and Canadian populations of beluga whales. Some protection from industrial development is being provided at locations where these whales commonly occur, but careful monitoring of existing stocks will be needed to secure the future of this attractive cetacean.