Authorities in Russia's Siberia region are investigating the deaths of 141 seals whose carcasses washed up on the shoreline of the world's deepest lake.

The Irkutsk region's government said in a statement that the dead seals were found on Lake Baikal's shores since last weekend. Authorities are ruling out an outbreak of a disease as the probable cause and say lab samples haven't shown what could have killed the animals.

The population of the Baikal earless seals, or nerpa, is estimated to be around 130,000.

The lake near the Mongolian border, 2,600 miles (4,185 kilometers) east of Moscow, contains 20 percent of the world's freshwater and is home to 1,500 species of plants and animals which exist nowhere else in the world.