An estimated 1,700 endangered seals were found dead Saturday on the southern Caspian coast of Russia.

Authorities in the Russian province of Dagestan, Russia, on the Caspian coast initially believed there were only 700 dead seals. After a more thorough inspection of the area, the number increased to 1,700 on Sunday, Zaur Gapizov, the head of the Caspian Environmental Protection Center, told state media.

Caspian Seals Found Dead
Dead seal on the coast of the Caspian Sea in Dagestan Caspian Conservation Center

Gapizov also stated that no evidence suggesting any of the seals were killed or caught in fishing nets. There was also no sign of pollution in the area, he said in a statement to the Russian news agency RIA Novosti.

"In a few days, 1,700 carcasses of Caspian seals were found on the coast of the Caspian Sea in Dagestan. Judging by the appearance of the seals we found, they died about two weeks ago. There were no signs of violent death, no remains of fishing nets. Most likely, the number of dead seals is much higher," Gapizov said.

Gapizov said the seals likely died a few weeks ago, but the cause is still unknown. The Federal Fisheries Agency and prosecutors were also said to have inspected the coastline and collected evidence for laboratory research to examine the possible cause of death.

Caspian seals have been on the endangered species red list of the International Union for Conservation of Nature since 2008. The seal population has decreased significantly from industrial pollution and overhunting for their fur and blubber.