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Peruvian dolphins die in their hundreds – seismic blamed

Oilfield Technology,

Over recent months, hundreds of dolphins and thousands of seabirds have washed up dead along the Peruvian coast. The bizarre spate of mass animal deaths in the region has led to both official and independent investigations of the event.


Earlier in the year, Peruvian officials attributed the deaths of so many dolphins to a virus or the consumption of toxic algae (as has occurred before in 1987 on American coasts); the most recent official investigation has concluded that they were killed by “natural causes,” although exactly what theses causes were has yet to be determined.

However, what Peruvian officials or more specifically, Gladys Triveno, the Peruvian Minister of Production and the person in charge of the government’s Ocean Institute, apparently can say for certain is that the deaths were “not due to any human activity.”

Environmental groups and NGOs, who claim to have found injuries in the dolphins that can only be caused by rapid decompression, hotly contest the finding of death by natural causes. It is this evidence that appears to contradict the official finding of human activity not being responsible for the deaths. Carlos Yaipen-Llanos, the director of a local NGO called ORCA, was quoted as sayng: “We found cells that had injuries due to bubbles that associated with decompression sickness … 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.”

The activity that has been blamed by environmentalist groups as the cause of the dolphins' deaths is offshore seismic exploration, conducted by oil and gas companies hunting for hydrocarbon reserves. The theory goes that the animals are panicked by sudden extreme noise, causing them to flee to the surface far more rapidly than they should, which results in them suffering rapid-decompression sickness or "the bends."

BPZ Resources, one company conducting seismic tests in the region, claimed that the deaths occurred far to the north of the area in which it was conducting its operations and had began to occur before the seismic exploration even started. The company also added that it stuck to strict environmental controls throughout its operations.

Whilst it would appear that the groups citing seismic exploration as the cause of the deaths have a solid case, government officials have chosen to disregard this conclusion; They claim there is no evidence to support the theory that the deaths were caused by seismic exploration and have cited similar dolphin mass deaths in New Zealand and Australia. 


The most popular explanation for the death of so many seabirds in recent months, especially Pelicans, is mass starvation. The heating of costal waters in the region has caused to the Pelicans’ main food supply, anchovies, to swim in deeper, cooler waters thus taking them out of reach of the birds. This proposed cause of death, much like that of the dolphins, has yet to be proven conclusively; the Peruvian government has, however, claimed that the two mass death events are not linked.

Another explanation...

Another theory behind the deaths from both species is poisoning as a result of dumped effluent and sewage entering the food chain. If the local anchovy population was affected by a sewage-derived toxin, it would impact upon both dolphins and Pelicans, who rely on the fish as a major source of food.

Written by David Bizley

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