At least 500 dolphins were sighted swimming slowly and stranded in the coastal area of Pilar town in Bataan.

The Bureau of Fisheries and Aquatic Resources (BFAR) described the situation as an “unusual phenomenon,” adding that the highest number of stranded dolphins the BFAR has recorded in the past only reached 20 to 30.

BFAR chief Malcolm Sarmiento said BFAR experts are looking at two possible reasons for the incident.

He said the dolphins could have been caught by a strong seaquake that could have damaged the dolphins’ eardrums that made them lose their sense of direction. Another possibility, he said, is that the pack of dolphins has a sick leader.

The governor of Bataan reportedly had already contacted the Subic Bay Metropolitan Authority and Ocean Adventure to bring in rescue teams to help the poor dolphins.