The
Baikal seal,
Lake Baikal seal or
nerpa (
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's Bay region of Quebec, Canada (
lac de loups marins harbour seals), the
Saimaa ringed seal (a ringed seal subspecies) and the
Ladoga seal (a ringed seal subspecies) are found in fresh water, but these are part of species that also have marine populations. It remains a scientific mystery how the seals originally came to Lake Baikal, hundreds of kilometers from any ocean.