IMARPE, the Peruvian Sea Institute, says 220 of the dead marine mammals were found during the last week of January alone.
Marine biologists say determining what’s killing the dolphins is difficult because their laboratories have only three or four of the approximately 100 chemicals available to solve the mystery.
But one institute official says the animals may have died from ingesting toxic algae.
Peru’s Organization for the Conservation of Aquatic Animals theorized in 2012 that the deaths were caused by ship sonar blasts used for seabed oil exploration, based on the damage found in some of the dolphins’ middle ear bones.
Peru denied those claims and said the deaths were due to “natural causes.”
Photos: Instituto del Mar del Perú (IMARPE)