The spill began on December 15, when two ageing Russian tankers were caught in a storm off the Kerch Strait linking Crimea to southern Russia.
One sank and the other ran aground, pouring around 2,400 tonnes of a heavy fuel oil called mazut into the surrounding waters, authorities estimate.
Russia’s Delfa centre, which rescues and rehabilitates dolphins, said it had recorded 61 dead cetaceans since the incident, 32 of whom “most likely” died due to the spill.
Cetaceans are a type of aquatic mammal that includes whales, dolphins and porpoises.
“Judging by the condition of the bodies, most likely the bulk of these cetaceans died in the first 10 days after the disaster,” it said on Telegram.
It said most of those killed were “Azov” dolphins — a type of harbour porpoise that look similar to dolphins but are more closely related to belugas and narwhals.
