Ukrainian prosecutors say the Russian military is to blame for the “mass destruction” of dolphins in the Black Sea—and they’re ready to file criminal charges over the ecocide. In a statement released Wednesday, the Odesa regional prosecutor’s office announced the start of criminal proceedings, saying a “large number” of the marine mammals have washed up dead on the shores of the Black Sea “as a result of Russia’s aggression against Ukraine.” The prosecutors said “the probable cause of their mass death” is Russia’s use of sonar equipment on submarines and boats, “which create powerful sounds that harm the health of the animals.” Several of the dolphins found dead have already undergone medical examinations, and samples will be sent to experts in Germany and Italy to confirm their cause of death, authorities said. Scientists have been sounding the alarm over the rise in dolphin deaths in recent weeks, with some of the creatures reportedly washing up on the shores of Turkey, Georgia, and Romania with signs they’d been hurt by mines or other explosives.