This lovely Cetacean is my favorite marine mammal and this text represents an assignment I did for an online course I completed on Marine Megafauna. It is purely my work based on the articles and books I have read from and it is destined for those who are interested in belugas or for those who love marine biology in general. This article had been published in a science magazine owned by an NGO that activates within my Faculty.
The beluga whale Delphinapterus leucas is a small toothed whale of the order Cetacea, suborder Odontoceti, the latter being represented by sperm whales, dolphins, orcas, beaked whales, narwhals and others. This species belongs to the Monodontidae family of Cetaceans and comprises only one other whale. Both the beluga whale and the narwhal are native to coastal areas at high latitudes in the arctic waters. The scientific name of the beluga whale, Delphinapterus leucas (named by Peter Simon Pallas in 1776) means white whale without fins. The beluga whale is the only species of the genus Delphinapterus, and it is the narwhal’s closest relative, in which the male is endowed with a long tusk. The beluga whale is commonly referred to as beluga, white whale, melonhead or sea canary because of the songs it sings.
Size and color
The beluga whale is a medium-sized whale that can grow up to 6 metres (19.7 ft) long, can weigh up to 1,600 kg (3,500 lb) and has an insulating layer of blubber that is 10-15 cm thick. Belugas are born with a brownish-grey colour, which turn grey in a matter of weeks. By the age of 6, the melanocytes in their tegument gradually lose the melanin, a process that causes these animals to have white skin.
The belugas generally have a circumpolar distribution in arctic and sub-arctic waters. A group of isolated belugas that was separated by the others during the last Ice Age can be found in the St. Lawrence River estuary of Canada. The other beluga pods migrate from the open freezing ocean to coastal areas in the winter months, but during the summer they can be found in deep waters in northern Russia, western Greenland, Alaska and northern Canada. Scientists can observe the animals only in the summer months and their social life is unknown in the winter. Their habitat includes sunlit shallow waters close to the coast (in fjords, bays, coves or canals) and deep waters, where they feed and give birth to their calves. Worldwide there are 29 recognised subpopulation of beluga whales, with a global population of around 150,000.
Without exception, the beluga whales are gregarious animals and tend to form social groups that vary between 2 and 25 individuals, and the pods can include males, females and calves. The belugas can live up to 50 years, but the average age is 25-30 years, especially because they can fall prey to humans, killer whales or polar bears.
Beluga whales mate in the spring, usually in March or April, in the safety of estuaries, bays or fjords. The males attract females with a variety of noises and their tail bends violently downwards, the head is thrown up and down and as a result the melon vibrates, signalling other beluga males that a specific female is taken. Gestation lasts around 14 months in the wild and nearly 16 months in captivity. Births generally occur in shallow, warm waters with a temperature ranging between 10 and 15 degrees Celsius and the baby belugas are able to swim next to their mother as soon as they are born and remain dependent to their mother’s milk for one year until their teeth appear. The number of offspring is always one with a breeding interval of once every two or three years. Female belugas reach the age of sexual maturity somewhere between 4 to 7 years and for male belugas it takes 7 to 9 years to reach reproductive maturity. As females age, there is a decrease in fertility and there are no births recorded for females older than 41.
The belugas are opportunistic feeders and they can forage on the seabed to depths of 20-40 meters, but they are known to dive to depths of up to 700 meters in search for prey. Some beluga whales have been observed to suck up water and then energetically expel it to uncover a possibly hidden prey on the seabed. A particularly interesting foraging behavior happens in the estuary of the Amur River that forms the border between China and Russia. Here, the belugas hunt in groups of six or eight individuals and they surround a shoal of fish to prevent their escape, and then the belugas take turns to feeding on the fish. These animals don’t have big, sharp teeth and therefore they have to swallow their prey whole using suction to trap it in their mouths. Belugas feast mainly on fish (capelin, herring, flounder, smelt etc.) and also on invertebrates (octopus, clams, sea snails, crabs, squid etc.).
A very special characteristic of this species is the fact that, unlike other cetaceans, they can nod and turn their heads almost 90 degrees to the side because they have seven unfused neck vertebrae. This feature gives these animals a flexible, well-defined neck, enabling then to turn their heads in all directions. Such structure can be helpful when beluga whales hunt for prey, raising the bar in the survival of this species.
For centuries the belugas have been hunted by native people of the Arctic for their skin and oil. That and also overfishing, have led to a decrease in population, especially in the Gulf of St. Lawrence. Belugas are the only cetaceans with skin thick enough to be used as leather when tanned. According to the IUCN Red List of Threatened Species, the conservation status of the beluga whale is categorized as near threatened, though in some locations such as Cook Inlet, the beluga population is considered endangered under the ESA (Endangered Species Act). Management responsibility for the beluga whales in Alaska has been delegated to NMFS (National Marine Fisheries Service) which has designated the Cook Inlet beluga population as below its optimal sustainable population, therefore depleted under the MMPA (Marine Mammal Protection Act). A conservation plan was proposed to restore the Cook Inlet beluga whale population to a minimum of 780 whales. The recovery plan identifies and assesses threats and in addition it defines strategies and identifies specific conservation actions needed in the struggle to save this species in the Cook Inlet.