At least 2,500 seals have reportedly washed up dead on Russia's Caspian Sea coast, along the Republic of Dagestan, according to news news channel CNN. Only 270,000-300,000 are estimated to exist in the wild, according to state-run media RIA Novosti. Screengrab: CGTNCaspian seals are the only mammals found in the Caspian Sea and have been classified as ‘Endangered’ on the International Union for Conservation of Nature (IUCN) Red List since 2008. Russian officials are probing the deaths and suspect the animals had died of “natural factors”. Screengrab: CGTNThe seals died about two weeks ago judging by their appearance, said Dagestan’s Ministry of Natural Resources. There were “no signs of violent death and no remains of fishing nets. Screengrab: CGTNFeeding mainly on fish, the seals can reach a length of more than 1.6 metres and weigh up to 100 kilogrammes. They are at the top of the food pyramid and have no natural enemies as adults, according to RIA Novosti. Screengrab: CGTN