Baikal seal

The Baikal seal, Lake Baikal seal or (Pusa sibirica), is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada (Lacs des Loups Marins harbour seals), as well as the Saimaa ringed seal and the Ladoga seal (both ringed seal subspecies), are also found in fresh water, but these seals are part of species that also have marine populations. The most recent population estimates are 80,000 to 100,000 animals, roughly equaling the expected carrying capacity of the lake. At present, the species is not considered threatened. The Baikal seal is one of the smallest true seals. Adults typically grow to in length with a body mass from . The maximum reported size is in length and in weight. There are significant annual variations in the weight, with lowest weight in the spring and highest weight, about 38–42% more, in the fall. The animals show very little sexual dimorphism; males are only slightly larger than females. They have a uniform, steely-grey coat on their backs and fur with a yellowish tinge on their abdomens. As the coat weathers, it becomes brownish. When born, the pups weigh and are about long. They have coats of white, silky, natal fur. This fur is quickly shed and exchanged for a darker coat, much like that of adults. Rarely, Baikal seals can be found with spotted coats. The Baikal seal lives only in the waters of Lake Baikal. It is something of a mystery how Baikal seals came to live there in the first place. The skull structure of the Baikal seal suggests it is closely related to the Caspian seal. In addition, the morphological structures in both species suggest they are descended from Arctic ringed seals. They may have swum up rivers and streams or possibly Lake Baikal was linked to the ocean at some point through a large body of water, such as the Tethys Ocean, West Siberian Glacial Lake or West Siberian Plain, formed in a previous ice age.