Russian authorities say they are investigating the death of more than 270 endangered seals that were discovered washed up on the shores of the Caspian Sea.
At least 272 dead Caspian seals have been found between December 6 and December 10 at a number of locations in the North Caucasus region of Daghestan, the regional branch of the state fisheries agency Rosrybolovstvo said on December 11.
Most of the marine mammals were found between Daghestan’s capital, Makhachkala, and the mouth of the River Sulak, a spokesperson told TASS, adding that more dead seals could yet be discovered.
A team from the Russian Academy of Sciences has arrived from Moscow to help conduct a probe.
Earlier, Rosrybolovstvo’s press service said the mass die-off may have been caused by a viral or bacterial infection as well as unfavorable weather conditions.
The Caspian seal is the only mammal living in the Caspian Sea, the world's largest inland body of water.
The endemic species has for decades suffered from overhunting and industrial pollution in the sea, and their number is now estimated at less than 70,000, down from more than 1 million in the early 20th century.
Listed as a threatened species by the International Union for Conservation of Nature’s (IUCN) since 2008, the seal was included in Russia’s Red Data Book of endangered and rare species this year.
The Caspian Sea, shared by five riparian states -- Russia, Kazakhstan, Azerbaijan, Iran, and Turkmenistan -- boasts vast oil and gas reserves.
Pollution from hydrocarbon extraction and declining water levels are posing a threat to many local species and putting the future of the sea itself at risk.