Conclusions on Dolphin Mass Mortality Event in Peru

A Mass Mortality of Dolphins:
Deadly Warning from the Beaches of Peru
By Hardy Jones, Executive Director,
BlueVoice.org

The tragic mass mortality event (MME) of at least 900 dolphins along the coast of northern Peru may be a portent of what would face marine mammal populations if seismic exploration for oil were permitted off the east coast of the United States.

See video http://bluevoice.org/webfilms_catastropheperu.php

The MME was investigated in a perfunctory manner by the government of Peru (GOP). Government agencies were reluctant to brave the remote beaches north of the fishing village of San Jose – the so-called stranding zone. There may have been some political concerns about offending the oil and fishing industries. And there is no funding in Peru for coordinated interdisciplinary investigations, as there is in the United States, when an MME is declared.

Whatever the reason, the GOP issued a statement concluding that “natural causes” and “evolutionary forces” were to blame for the massive die-off of dolphins. That statement is clearly ludicrous.

I believe there is enough circumstantial evidence to state that a plausible cause of the death of the dolphins along the coast of Peru would be seismic exploration for oil that was being carried out in the area of the MME. The extremely loud sounds generated by detonation of powerful air guns can cause dolphins feeding at depth to race to the surface. If they surface too rapidly, bubbles develop in their tissues causing death. This recognized phenomenon is called acoustical trauma, rapid ascent decompression syndrome. It leads to decompression sickness, commonly called the bends.

Scientists once thought marine mammals such as whales and dolphins were not subject to decompression sickness because they do not breathe compressed air. But a recent study in the Proceedings of the Royal Society1 said researchers had recorded deaths among marine mammals as a result of decompression sickness, primarily among beaked whales “in association with anthropogenic activities such as military sonar or seismic surveys.”2


My conclusion comes after months of investigation, including an 85-mile drive along the sands of northern Peru and email exchanges with top experts in marine mammal rescue and previous MMEs.

As the investigation into the cause of the Peru dolphin MME continues, The Obama administration is proposing to open vast offshore tracts between Florida and Delaware to seismic surveys for potential oil deposits. The oil industry has applied to Minerals Management Service (MMS) and The Bureau of Ocean Energy Management (BOEM) to run hundreds of thousands of miles of air gun surveys off the east coast over the next eight years. The Obama administration estimates these detonations would injure up to 138,500 marine mammals.

My investigations in Peru gave me a horrific view of the possible results of what may have been seismic testing that was being conducted in areas frequented by thousands of common dolphins. To give some background; beginning in February 2012 hundreds of dolphins were reported stranded (dead) on the beaches of northern Peru. In March I joined Dr. Carlos Yaipen Llanos of the Peruvian Organización Científica para Conservación de Animales Acuaticos (ORCA). During a single 85-mile drive along the beaches in the stranding zone, we counted 615 dead dolphins. Most were long beaked common dolphins. A few were Burmeister’s porpoise.

Dr. Yaipen Llanos, funded in large measure by BlueVoice, collected tissue samples from thirty dolphins. He conducted necropsies in situ and in Lima. After extensive testing he was able to rule out possible causal factors:

-The dolphins were not killed by fisheries interaction. -Their bodies were unscarred as they would be if they had died from net entanglement.
-There was no evidence of red tide and no species other than the two mentioned were affected.
-A contemporaneous mass mortality of pelicans was the result of starvation when their prey moved into deeper waters due to the end of a La Nina. There is no connection to the dolphin mortality.
-The deceased dolphins were well fed and healthy in appearance. A female, very recently stranded, had milk in her mammary glands.
-Morbilla virus, related to distemper, and Brucella bacteria, two pathogens commonly associated with mass mortality events, were ruled out by Dr. Yaipen Llanos. No symptoms of these diseases were found.

The Peruvian government report concurred in finding none of the above-mentioned factors complicit in the deaths of the dolphins.

What is not known, because it was not measured, is whether the dolphins suffered exposure to a huge quantity of either heavy metals or organic pollutants.

Based on the necropsies of 30 dolphins (the GOP had only three organs from two dolphins), Dr. Yaipen Llanos concluded that acoustical trauma leading to rapid ascent and decompression syndrome was the cause of death of the dolphins.

Dr. Yaipen-Llanos stated to me that necropsies that he and his colleagues performed on three separate expeditions to the stranding area showed the dolphins investigated had bleeding in their middle ears and had suffered fracture to the periotic bones that surround the inner ear. He also found gas in their internal organs and acute pulmonary emphysema, symptoms all consistent with death from decompression sickness.
Dr. Yaipen Llanos found newly stranded animals on each of ORCA’s three expeditions, showing the death of the dolphins was an ongoing process. He issued a statement saying “we believe that a strong source of sound was continuously emitted in the area. This didn’t happen just once.” He specifically did not name seismic testing as a cause, stating it was outside his professional competence.
During the course of my research I found widespread resistance from highly qualified experts to the idea that acoustical trauma was the cause of the dolphin mass mortality. NB: None of these scientists had been on scene and had gathered what little information they had from the GOP. The GOP dismissed the acoustical trauma hypothesis outright. Dr. Joseph Geraci3 told me “there is no scientifically verified case of seismic testing ever causing a mass mortality event.”

Dr. Robert Brownell of the National Oceanic and Atmospheric Administration (NOAA) of the U.S.A also discounts the acoustical trauma theory, though he says he needs much more information before coming to a solid conclusion. But he also told me of “a mass stranding of melon-headed whales off northern Madagascar about June 2008 – (a major oil company) was working in region at the time.” He went on to say “a group of us has been trying to organize (a) workshop but (it’s) difficult with government of Madagascar (not cooperating). The possibility of a mass stranding in Madagascar caused by seismic testing does not refute Dr. Geraci’s statement in which he emphasizes the words “scientifically verifiable.” Since Madagascar won’t allow an investigation there will likely never be a “scientifically verifiable” cause of death assigned.

Dr. Brownell, Dr. Frances Gulland of the Marine Mammal Stranding Center near Sausalito, California and a number of other prominent experts on MMEs are hoping to put together a conference in Peru – perhaps in the fall of 2012.

In the meantime arguments go back and forth:

GOP: Dolphins began dieing in January and the seismic tests didn’t start until February

El Commercio, Peru’s most widely read newspaper, reported that the Peruvian Navy Had given permission for foreign oil companies to carry out seismic testing as early as November.

Various scientists: The bubbles described by Dr. Yaipen Llanos could have been the result of putrefaction in the dolphin corpse.

Dr. Yaipen Llanos: the fresh dolphin carcasses he examined had excess bubbles that differed from putrefaction bubbles.

And again, there is the GOPs conclusion that the MME was caused by natural causes and evolution.

No rebuttal required but laughter.

There will likely be no universally agreed upon conclusion on what killed more than 900 dolphins along the coast of Peru. The most plausible cause, the one that has not been disqualified, is seismic testing for oil. At very least this possibility needs to be factored into decisions on permitting this form of testing in the future.