The large Siberian freshwater lake that is the only habitat of the Baikal seal is Lake Baikal. The seal, also called the nerpa, is endemic to this ancient lake in southern Siberia, Russia.
Baikal seals are unusual because they are one of the few pinniped species that live exclusively in freshwater. Their closest relatives include Arctic ringed seals and Caspian seals. Scientists think their ancestors may have reached the lake through ancient rivers or inland waterways, but the exact route remains uncertain. The species may have occupied Baikal for roughly two million years.
The seals feed largely on golomyanka, a fish found only in Lake Baikal, along with other fish and small aquatic animals. During winter, they use breathing holes in the lake's ice and give birth in ice dens. Northern parts of the lake often attract more seals because the ice lasts longer there.
Lake Superior, Lake Victoria, and Lake Tanganyika support many freshwater species, but none is the exclusive natural home of the Baikal seal. That geographic restriction is what makes Lake Baikal central to the species' survival.