A study by an environmental group that suggested explosions from oil exploration were to blame for the deaths of nearly 900 dolphins off Peru’s coast has been refuted by the government on Wednesday, which said the dolphins died of natural causes.
At least 877 dolphins have died since the start of the year. According to Fisheries Minister Gladys Triveno, Peru’s Maritime Institute (IMARPE) found the massive die-off was not the result of lack of food, hunting, poison, contamination, and infection or virus. It also said there was no conclusive evidence that linked seismic offshore exploration by oil companies to the dolphin deaths.
“We have reached the conclusion that the deaths were from natural causes. It’s not the first time that this has happened” Triveno said, citing similar cases of dolphin deaths in New Zealand and Australia.
Environmental groups are unconvinced with the government’s finding and continue to believe oil exploration in the area was the cause of the massive die-off. The Scientific Organization for the Conservation of Aquatic Animals (ORCA) said it had tested 30 of the dead dolphins and found they had broken ears and damaged organs, consistent with them suffering from decompression sickness, due to noise and pressure waves caused by explosions.
“We found cells that had injuries due to bubbles that are associated with decompression sickness,” Carlos Yaipén-Llanos, director of ORCA, told Reuters.
The government and independent scientists said it is impossible to prove the dolphins died of decompression sickness. And Houston-based BPZ Resources said the dolphin deaths were occurring even before they started their seismic surveys on February 8. Another company, Savia Peru, said it was not working in the area during the time of deaths.
Both oil companies said seismic surveying is used widely around the world and has never been linked to massive die-offs before.
IMARPE left open the possibility that unusually warm surface waters and high levels of algae could have played a role in the dolphins’ demise, calling for further analysis to determine if any red and brown plankton species were toxic, Triveno noted.
The warm surface waters are also being blamed for massive die-offs of pelicans in the area. The abnormally warmer surface temperatures drove anchovies lower down in the cooler depths where pelicans are unable to dive deep enough to reach them. As a result, about 5,000 pelicans starved to death.
While there is no link between the pelican and dolphin deaths, experts said Peru’s northern coast is often affected by temperature oscillations between the warmer equatorial waters and the frigid Humboldt current that runs north from Chile.
The region is also in a transition phase from the La Nina to El Nino weather phenomena that occur in the southeastern Pacific, according to Bill Patzert, an oceanographer at Jet Propulsion Laboratories in California.
The warm surface waters often bring foreign plankton to coastal areas, said Patzert. “When you see a massive die-off of bird species and marine mammals, often it’s some kind of weird toxic bloom,” he told Reuters reporter Caroline Stauffer.
Triveno said there would be a separate report into the pelican deaths.