Authorities in Peru seems to be completely clueless as to why so many dead dolphins have washed up on their beaches over the past two months. Officials hope to have some answers on the subject when their investigation into the matter wraps next week.

The carcasses of 877 dolphins and porpoises began washing up on shores last February. The number has only continued to grow as the months wear on. Likely culprits behind the mysterious deaths include infection or diseases, though nobody seems to be able to put a finer point on it. Scientists do feel, however, that these issues have nothing whatsoever do to with the exploration work currently taking place in the waters north of Peru.

“Right now, the most probable hypothesis is that it’s a virus outbreak,” Deputy Environment Minister Gabriel Quijandria told CNN.

According to report, roughly 80% of the bodies were discovered partially decomposed, which makes it difficult for officials to properly determine the cause of death. Preliminary investigations have determined that the deaths were not attributed to ” lack of food, interaction with fisheries, poisoning with pesticides, biotoxin poisoning, or contamination by heavy metals.”

Authorities currently feel that Morbillivirus or Brucella is the likely cause of death.

These unfortunate events, however, are not just a regional occurrence. According to The International Fund for Animal Welfare, 108 dead dolphins washed up on shore in Cap Code last February.

“We experience mass strandings several times each year. The events may involve only a few animals or hundreds,” said IFAW manager of marine mammal rescue and research Katie Moore. “The causes of these events are often not determined, which is a frustrating fact.”

Recently, 30 dolphins who beached themselves in Brazil were rescued by concerned locals. The whole event was captured on amateur video, which you can watch below.