The beluga or white whale (Delphinapterus leucus), known as qilalugaq in Greenlandic and Inuktitut, puugzaq in Siberian Yupik, and sisuaq in Inupiat, is a mid-sized toothed whale (odontocete). The whale is white as an adult, and beluga is derived from the Russian word for white. Males are considerably larger than females, the former reaching lengths of 5 m and weights of 900 kg. Females reach a maximum of 4 m and 600 kg. White whales lack a dorsal fin, but they have a prominent dorsal ridge that is used to break through thin ice. They have small eyes, a bulbous forehead (termed a melon), and a flexible neck (unlike most cetaceans that have fused neck vertebrae). They have small flippers and a small fluke or tail lobe. When white whales are born, they are creamy-gray in color, but turn dark gray rapidly. They fade in color over their juvenile years, becoming lighter each year until they are eventually white. Females are white by about age 7, whereas males are about 12 years when they are completely white. White whales can appear a rusty yellow prior to their summer molt. White whales live to an age of approximately 40 years.
White whales are found in most Arctic and Subarctic waters, including the Arctic Ocean and its adjacent seas. However, their distribution is somewhat discontinuous as they are virtually nonexistent in the Greenland Sea. A small, southern population of white whales resides in the St Lawrence River. The global population of white whales is not accurately known, but the summation of various stock estimates suggests about 200,000 animals. White whales travel deep into drifting ice, where the ice cover can be 90%+. White whales exhibit highly variable movement patterns in different geographical areas of the High Arctic. In some areas they exhibit marked migratory patterns, while in other areas they remain resident year round. In some areas they spend a lot of time in coastal, occa-
sionally even in estuarine, areas during summer, while in other areas they occur far offshore. In some areas white whales tend to follow the seasonal movement patterns of the sea ice distribution, remaining near the expanding or retracting ice edges. Although the winter whereabouts of white whales are poorly known, it is assumed that they either overwinter in areas containing polynyas or predictably open leads in the ice or they migrate in the direction of the advancing polar ice Peak birthing occurs in April-May, but births can be spread from late spring through until early fall. The gestation period lasts approximately 14 months. The social dynamics of this species are not well documented, but mating is thought to occur primarily in the late winter. Calves are cared for by their mothers for over 2 years, and remain in the maternal social group for years following their weaning as juveniles. Mothers are very solicitous of their young, and young calves are virtually always in physical contact with their mothers. Mother-pup pairs are also very vocal. Similar to all cetaceans, mother white whales squirt milk into the mouths of their calves using contractile muscles associated with the mammary glands. The reproductive interval for females is on average 3 years. White whale females reach sexual maturity at about 5 years of age, whereas males are somewhat older (8 years).
White whales usually feed in waters above the continental shelf, consuming a wide variety of prey items ranging from benthic invertebrates and squid to pelagic fishes. In summer they often occur in dense concentrations at discrete coastal locations, including river estuaries, where they may feed on seasonally abundant anadromous (salmonids) and coastal fishes in some parts of their range. In western Greenland white whales consume pelagic polar cod and Arctic cod. In Svalbard their diet appears to be dominated by polar cod, and capelin and shrimps may also be important prey at this location. In Svalbard white whales spend a lot of their time along glacier fronts, presumably because upwellings in these areas result in concentrations of prey being available. White whales can dive to depths greater than 1000 m and remain submerged for 25 min.
Polar bears and killer whales are both predators of white whales. If the whales become trapped in cracks or small winter ponds in the ice, bears can harvest the entire pod as they weaken after repeated attacks each time they surface to breathe. Killer whales are thought to be a major force in keeping white whales tightly associated with ice, where the orcas cannot follow them. Walruses are also purported to be a predator of white whales, although it is difficult to envisage a situation where they would fall prey to this potential predator.
White whales are very social animals that travel in groups virtually all the time. There is significant sexual segregation among groups: females, calves, and juveniles travel together, while adult males form separate groups. Groups are not fixed entities; they seem to divide and reconsolidate through time. White whales are highly vocal in most areas within their range, and have a diverse repertoire of acoustic signals. They have extremely well-developed echolocation that is well adapted to Arctic waters; they can project and receive signals off the surface and detect targets despite high levels of ambient noise and backscatter, which allows them to navigate through heavy pack ice. White whales are highly adapted to the Arctic, similar to narwhal and bowhead whales. They have very thick blubber, and a dorsal ridge (without a fin) that can be used to break through thin sea ice. This species lives most of its life in close association with sea ice. It has an annual molt, which is unique among cetaceans.
White whales are harvested for subsistence purposes throughout their range in the Arctic. In some areas the numbers taken are significant because their coastal distribution in summer makes them readily available to shore-based fisheries. It is one of the most important species in traditional hunts in coastal Alaska, the eastern Canadian Arctic, and Greenland. There is concern that catches in the eastern Canadian Arctic and in Greenland probably far exceed the sustainable yield for a toothed-whale population, and it appears that these stocks have suffered declines ranging from 30% to 60% within the last decade. White whales have been subjected to commercial harvests by various nations at various times, and until very recently were commercially harvested by Russia in the White Sea. In Svalbard, Russian whalers began harvesting this species early in the 17th century, mainly operating in the fjords on the West Coast of Spitsbergen. Norwegians and other nations commenced hunting for white whales in this region in the late 1800s when the larger whales became scarce. Thousands of white whales were harvested during the latter part of the 18th and the beginning of the 19th centuries in the Barents Sea region, but commercial harvesting no longer takes place.
See also Marine Mammal Hunting; Whaling, Historical
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