More than a dozen dead dolphins have washed up on Georgia’s Black Sea coastline, with authorities unsure why.

A total of 19 dead dolphins were spotted this month washed up along the coastline from Ganmukhuri to Sarpi, agenda.ge reports.

Authorities said they didn’t know the exact cause of death but suggested it could be a result of dolphin morbillivirus, a virus that infects marine mammals.

“Experts from the Fishery and the Black Sea Monitoring Department of the National Environmental Agency are carrying out research regarding this issue,” authorities said.

Meanwhile they warned citizens to be careful and not to touch the dead dolphins.