Manila (AsiaNews/Agencies) - Filipino environmentalists continue to monitor the coast of the province of Bataan, west of the bay of Manila, to prevent more beachings of dolphins. About 300 of the mammals got stuck yesterday.

Dozens of volunteers and fishermen from the villages of Pilar and Orion immediately plunged into the sea, to help the dolphins stranded on the coast. An underwater tremor or a sudden heat wave are the hypotheses favored by the experts to explain how the dolphins lost their sense of direction.

It is not rare to see dolphins run aground in the Philippines, but the phenomenon had never before been seen on such a large scale. Quick action by the inhabitants of the area prevented genuine carnage. They plunged into the ocean en masse, trying to frighten the dolphins to make them swim away. A group of boats then guided them out to sea, into deeper water.

Out of the 300 that were beached - of the genus Peponocephala, found throughout tropical waters around the world - only five of them died, one of them a pregnant female. Malcom Sarmiento, director of the Bureau of Fisheries and Aquatic Resources, calls the phenomenon "unusual" because of its large scale, and explains that it could have been caused by "a heat wave or disturbance at sea." This could have caused the entire school to lose its sense of direction, or just the leader, which the other dolphins would have followed to the shore.