(NaturalNews) Hundreds of dead dolphins splashed up on northern Peru's Pacific Ocean beaches in January, confounding scientists and marine biologists.
In all, officials say more than 400 of the mammals have washed ashore in a region where more than twice that amount were found in 2012, The Associated Press (AP) reports.
Authorities have so far been unable to figure out why the dolphins were dying in 2012 but are currently in the process of performing autopsies on the latest dolphins to wash ashore last month, in the Lambayeque region of Peru's north coast.
As reported by AP:
Technician Jaime de la Cruz of Peru's IMARPE marine life agency said about 220 dead dolphins were found in the last week of January, the rest during the previous three weeks.
De la Cruz said autopsy results are expected [soon]. Exams will focus on lungs, kidneys and livers.
Officials and experts are stumped
Autopsies performed on more than 870 dolphins discovered in 2012 were not conclusive, Peruvian officials have said. But some experts have speculated that perhaps biotoxins in the sea may be responsible. Others have suggested seismic testing or some as yet unknown sickness.
The director of the marine biology unit at Cayetano Heredia University, Yuri Hooker, told AP that dolphin deaths in other parts of the world most often occur due to some form of environmental contamination, such as when they eat fish or other smaller species that are filled with toxins. He said others can die after eating plastics floating in the sea after being discarded.
Hooker added that finding out what killed the latest group of dolphins is going to be "complicated" in Peru, because the government laboratories have only about three or four of the world's 100 or more chemical reagents that can be utilized to determine an animal's cause of death.
Nature World News added:
Additionally, more than 1,500 birds, mostly brown pelicans and boobies, died between February and May 2012 in Peru. Officials said there was no link between the bird deaths and the dolphin deaths.
As reported by The New York Times, the dolphins washed ashore partially decomposed, suggesting that they died at sea. But the bird deaths appear to have occurred onshore.
'It definitely is odd'
"Never in my 40 years as a fisherman have I seen anything like this," Francisco Niquen Renteria, the president of the Association of Artisanal Fishermen in Puerto Eten, in the Lambayeque region, told the Times. "Sometimes in the past, you'd randomly see a dead dolphin or a pelican, but this, what's happening now, is really alarming."
Gabriel Quijandria, the deputy environment minister, further acknowledged, "It is odd indeed. But [the deaths] are not related."
Officials with the federal Ocean Institute said the most likely cause of death for the dolphins is morbillivirus, from a family of viruses linked to previous mass deaths of marine mammals. But in recent days, however, experts say they are less certain that that is accurate.
As for the birds, the Times reports Quijandria having wrote that "the 'most plausible hypothesis so far' from the National Agricultural Health Service is that they are dying from a lack of food, mainly anchoveta (Engraulis ringens), a Peruvian anchovy, as a result of the sudden heating of coastal waters."