Baikal seal (Pusa sibirica)
|Also known as:||Lake Baikal seal, nerpa|
|Size||Length: 110 – 142 cm (2)|
|Weight||50 – 130 g (2)|
Classified as Least Concern (LC) on the IUCN Red List (1).
The Baikal seal is remarkable for being the only pinniped that is restricted solely to a freshwater habitat (2). Like other pinniped species, it may look rather ungainly on land, but in water it transforms into a remarkably graceful and agile animal. This is aided by its torpedo-shaped, flexible body (3), and powerful hindquarters which move side-to-side to propel the seal through the water (4). Its long, broad, webbed feet act as efficient flippers, while the smaller forelimbs are used to steer (4). The dense fur of adult Baikal seals is dark silvery-grey on the upperparts, blending into lighter yellowish-grey on the underside (2) (5), while pups are born with long, white hair (6). Under the seal’s fur and skin is a thick layer of blubber, which not only provides vital insulation in its icy habitat, but also aids buoyancy, protects the internal organs, and acts as an energy store (3). Other adaptations for its primarily underwater life include large eyes which enable good vision in deepwater, and ear passages and nostrils that can be closed underwater (3).
The Baikal seal is confined almost entirely to Lake Baikal in Russia, the deepest lake in the world. Occasionally, this seal may also be seen in the rivers that flow into and out of this expansive lake (1) (2).
The Baikal seal is found only in freshwater, and is the only seal with this trait (2). Lake Baikal is a unique habitat, holding the record of being not only the deepest lake in the world, but also the oldest and the largest in volume (7). During the winter, the lake is almost completely covered with ice, measuring 80 to 90 centimetres thick (2).
A year in the life of the Baikal seal is heavily driven by the unique habitat in which it is found (1). During winter, when the lake is largely covered with ice, seals can be found throughout the lake, particularly in the deep water in the centre (1), utilizing holes in the ice to breathe (2). The Baikal seal uses its strong foreclaws, as well as its head, teeth and rear flippers, to keep these vital access holes open (2). Although the Baikal seal is a largely solitary animal, several individuals may share access holes, and at certain times of the year, large groups may gather in areas of favourable habitat, such as around April, when the ice begins to break up and the seals start to congregate at new openings in the ice to feed (2).
The month of May marks the peak of the breeding season. Male Baikal seals are believed to be polygynous, meaning that they mate with more than one female (2). Mating is thought to take place underwater, and it is suspected that there is delayed implantation (2). In late winter and early spring, following a gestation period of nine months (2), pregnant females move onto the ice, where they build an ice den in which the pup is born (1). The home range of each female on the ice, which incorporates the den and breathing holes, does not overlap with other females (1).
Baikal seals typically give birth to just one pup, although twins, whilst uncommon, are more frequent than in other pinnipeds (2). The newborn seals, camouflaged on the ice with their white, woolly coats, do not enter the water until two or three weeks old (1). At six weeks of age, the pup’s white coat begins to be replaced with the darker, adult fur, and they are fed milk by their mother until up until 2.5 months. Male Baikal seals become sexually mature at seven years of age, while females reach sexual maturity about a year earlier (2). They can continue to reproduce until 43 to 45 years of age (1), and with a maximum recorded life span of 56 years (2), this species may have the greatest longevity of any pinniped (1).
As the ice breaks up further in May and June, the Baikal seal undergoes its annual molt (1) (2), while summer sees the seals concentrating in the southeastern part of the lake, where they haul themselves onto the shore and rocky islands between feeding trips (1). The Baikal seal feeds primarily on fish species which have no commercial value to humans (2), and juvenile seals may also consume amphipods (1). It feeds mainly at twilight and during the night, diving down to typical depths of 10 to 50 metres for 2 to 4 minutes to hunt its prey (1).
For a very long time, the Baikal seal has been the target of subsistence hunters, but it was not until the second half of the 18th century that it became the subject of a commercial hunt for pelts, oil and meat (1) (2), with excessive hunting, particularly in the 1930s, seriously reducing its numbers (2). Today, harvesting of the Baikal seal continues, although at levels that are not believed to threaten the survival of the species (1).
Other potential impacts on the Baikal seal arise from pollution of the lake (1). Unfortunately, this ‘pearl of Siberia’ is adversely affected by factories and towns, situated on its shores, which taint the lake with sewage and industrial waste, and the use of fertilisers and pesticides on surrounding agricultural land (7). Baikal seals are considered to be heavily contaminated with pollutants, possibly at levels which may make them susceptible to their toxic effects (1). The recent opening of nearby oil fields and the Baikal-Amur railway line have further stimulated the development of industry near Lake Baikal, which may have unknown detrimental impacts on the lake habitat, and therefore the seal (1). Outbreaks of disease are another potential threat to this species; an outbreak of the phocine distemper virus killed an estimated 6,500 seals in 1987 and 1988, and the virus continues to circulate in the population (1). Finally, if the trend of global warming continues, the quality of the Baikal seal’s habitat will deteriorate, possibly inducing a population decline (1).
Over the years, several measures have been implemented to regulate hunting of the Baikal seal. These include quotas, specifying the times of the year at which the seal can be hunted, and restricting the age of seal that can be taken (1). As the Baikal seal is currently a well-monitored species, any population declines that do occur should be detected, allowing appropriate conservation measures to be promptly implemented (1).
Lake Baikal itself is a Natural World Heritage Site (8), and parts of the lake and its basin are designated Nature Reserves and National Parks (9). Many local laws and regulations are in place to protect the lake, but an integrated management plan and comprehensive monitoring of this biologically diverse lake is still needed (9). Environmental non-governmental organisations, such as Greenpeace, campaign to protect this incredibly important source of freshwater. Greenpeace is currently focusing its efforts on Baikalsk Pulp and Paper Mill, which is located on the shore of the lake and discharges chlorine, used in the paper bleaching process, directly into the lake (10). Any successes at reducing pollution of the lake will undoubtedly help safeguard the future of the unique Baikal seal.
For further information on the conservation of seals and Lake Baikal see:
Seal Conservation Society:
For more information on the Lake Baikal seal, visit:
BBC Wildlife Finder:
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- Amphipods: a group of small shrimp-like crustaceans that includes sandhoppers, beach hoppers, and water lice.
- Delayed implantation: the process of a fertilised egg remaining unattached in the uterus for a period of time, therefore delaying the start of development.
- Gestation: the state of being pregnant; the period from conception to birth.
- Pinniped: a carnivorous, aquatic mammal belonging to the Pinnipedia, which includes the seals, sea lions and walruses. All have four limbs modified into flippers.
IUCN Red List (June, 2008)
- Nowak, R.M. (1999) Walkers Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
- Burnie, D. (2001) Animal. Dorling Kindersley, London.
- Macdonald, D.W. (2006) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
- Miyazaki, N. (2003) Ringed, Caspian and Baikal Seals. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds) Encyclopedia of Marine Mammals. Academic Press, London.
- Reijnders, P., Brasseur, S., van der Toorn, J., van der Wolf, P., Boyd, I., Harwood, J., Lavigne, D. and Lowry, L. (1993) Seals, Fur Seals, Sea Lions and Walrus. Status Survey and Conservation Action Plan. IUCN, Gland, Switzerland.
- Stewart, J.M. (1991) Lake Baikal: On the Brink?. IUCN, Gland, Switzerland.
UNESCO World Heritage Centre (October, 2008)
UNEP-WCMC: Protected Areas and World Heritage (October, 2008)
Greenpeace (October, 2008)