ISTANBUL 

More than 320 seals were discovered dead Tuesday on the Caspian Sea coast between the estuary of the Sulak River and the Terek River in Dagestan, a republic in southwestern Russia, the Tass news agency reported.

The number of dead animals found could increase, the report said, citing the regional emergency response services.

Earlier, the Dagestan Ministry of Natural Resources noted that Caspian seal deaths are quite common during the mammals' annual migration period.

“Scientists believe the main cause is asphyxiation of animals passing through areas of powerful natural gas emissions from the seabed associated with seismic activity,” said the ministry.