On Russia's Caspian Coast, a Grisly Find

About 2,500 Caspian seals have been found dead on the Caspian Sea coast in southern Russia, officials said Sunday. Authorities in the Russian province of Dagestan initially said it was unclear why the mass die-off happened, but a top Russian environmental official on Monday said the cause of death was likely hypoxia, or oxygen deprivation. Svetlana Radionova of the natural resources watchdog agency Rosprirodnadzor said on Russian state television that scientists are investigating whether natural gas emissions in the Caspian could account for low oxygen. The Caspian Sea has extensive natural gas reserves that are being tapped increasingly, reports the AP.

Zaur Gapizov, head of the Caspian Environmental Protection Center, said in a statement that the seals likely died a couple of weeks ago. He added that there was no sign that they were killed or caught in fishing nets. Several previous incidents of mass seal deaths were attributed to natural causes, per the AP. Kazakhstan, which has a long Caspian coastline, reported at least three such incidents this year. Data about the number of seals in the Caspian vary widely. The fisheries agency has said the overall number of Caspian seals is 270,000-300,000, while the Caspian Environmental Protection Center put the number at 70,000. The Caspian seals are the only mammals found in the landlocked Caspian Sea, notes CNN, and the seals have been classified as endangered since 2008.