“One of the things that we can confirm is that … the deaths of the dolphins were not caused by any human activity, and this is a very important subject,” Peruvian Production Minister Gladys Triveno told RPP Radio.
Government investigators have also ruled out theories that bacteria or a virus could be behind the deaths, she said, adding that further details would be revealed in a report from the Sea Institute of Peru released Tuesday.
“It is natural causes. It is a natural death, and also the report explains the process of natural selection. Let’s say that the species that are more prepared, the dolphins that are more prepared, are those that are going to survive,” Triveno said. “And this happens periodically. This is not the first time it has happened. And it is not only happening in Peru, but also has happened in New Zealand, in Australia, in other countries where these phenomena happen.”
What is killing the dolphins in Peru? Mystery animal deaths = beach warning Animal deaths stump experts in Peru
According to the report, authorities sent specimens to no fewer than four laboratories for a battery of tests.
The results ruled out a number of theories of the cause of death. Hunger, interaction with fishermen, pesticides, bacterial infections, viral infections and heavy metals contamination were all ruled out.
The appearance of nearly 900 dead dolphins in a 220-kilometer (137-mile) area in northern Peru so far this year, and the deaths of thousands of pelicans there and in neighboring Chile, have sparked concern among local residents and environmentalists.
At least one Peruvian environmental group has said loud sounds from nearby oil exploration could be to blame for the dolphins’ deaths.
“We see that in their bodies there are air bubbles caused by heavy pressure. These animals are underwater holding their breath, facing a sudden and violent noise. These animals release nitrogen, and this forms the bubbles that end up destroying living cells,” Carlos Yaipen-Llanos of the Scientific Organization for the Conservation of Aquatic Animals told CNN en Español this month.
Government officials have dismissed that assessment, arguing that it is not supported by evidence.(CNN)