Fresh Water Seals Lake Baikal

The Nerpa lives only in the waters of Lake Baikal, on the edge of Siberia, the world's deepest freshwater lake and the largest by volume, accounting for 20% of the world’s freshwater. Baikal is 700km long, 70km wide and more than 1.5km deep at some points. (Schofield, 2001; Harrold, 2002) It is also several hundred miles inland, so it is somewhat a mystery as to how the Nerpas came to live there in the first place. It can be speculated that they swam up rivers and streams or that possibly Lake Baikal was linked to the ocean at one point as the result of a large body of water formed in a previous ice age. No one knows how they actually arrived at Lake Baikal, but it is suspected that they have been inhabiting that location for 20 million years. The nerpa and the Saimaa Ringed Seal Phoca hispida saimensis are the only exclusively freshwater seals.

The areas of the lake in which the Nerpas reside change depending on the season as well as some other environmental factors. The Nerpas are solitary animals for the majority of the year, sometimes living kilometers away from other Nerpas. In general, there is a higher concentration of Nerpas in the northern parts of the lake, because the longer winter keeps the ice frozen for longer, which is preferable for breeding. However, in recent years there have been migrations to the southern half of the lake. These are speculated to be evasive action against hunting. In the winter, when the lake is frozen over, they maintain a few breathing holes over a given area, and tend to stick to that area, not interfering with the food supplies of a nearby neighbour. When the lake begins to melt, the Nerpas tend to stick around the shorelines.