"It probably would be the first time that seismic testing had ever been implicated in this kind of mass mortality of dolphins," say Hardy Jones, a wildlife documentary maker for the last thirty years.

Thousands of dolphins wash up on the northern coast of Peru. Are they victims of seismic testing?

The debate over high-decibel seismic testing is not just local.

Scientists in South America are researching whether it's the cause of mass marine life deaths.

In February of this year, thousands of dolphins began dying and washing up on Peruvian beaches.

During that same time period, BPZ energy was doing a seismic survey in the same area where the dolphins had turned up.

The mystery surrounding their deaths continues to be a subject of discussion among many in the scientific community.

It's a tragic sight.

Thousands of dolphins lie dead on the beaches of Peru earlier this year.

"It was a tragic and heart rending thing to see and then of course we began to look for what the cause was," says Hardy Jones.

Wildlife documentarian Hardy Jones believes these casualties were caused by the same types of seismic tests that are proposed here on the Central Coast.

Jones and Peruvian veterinarians performed more than 30 necropsies, or animal autopsies, and this is what they found.

"The plausible conclusion that we came to was that an acoustical trauma caused rapid assent among the dolphins and then that led to decompression sickness," says Jones.

If you're a diver you know this all too well. Jones says, like humans, dolphins must decompress before heading to the surface from deep water. But he says the loud bangs of the air cannons startled the animals to the surface too rapidly, causing their deaths.

He says they found bleeding and simple fractures of the middle ear, and massive invasion of air bubbles which shifted vital organs such as lungs, livers, kidneys, bladders and blood vessels.

But Frances Gulland disagrees with the findings.

She's a scientist and veterinarian at the marine mammal center in Saucelito, California.
Peruvian scientists went to her for help in interpreting their testing.

"So there were a mixture of different species that appeared to be affected over an extended time period at various stages of decomposition, suggesting that there wasn't a single cause of death that occurred at one time," says Gulland.

Gulland says there's a long list of potential causes for the dolphin deaths.

"From environmental changes, changes in food supply, changes in interaction with fisheries, infectious diseases such as the influenza and other viruses, as well as bio toxins that could not be detected in the samples that were tested," says Gulland.

Other scientists say these types of seismic surveys only affect the way marine life acts.

"Most of the effects we might expect and that were predicted were behavioral responses," says Brandon Southall.

Dr. Brandon Southall worked with a federal sea mammal research unit to develop the environmental impact report being used for the seismic testing near diablo canyon.

He says these types of studies typically don't cause injury or death in marine animals.

But he adds behavioral changes can still pose a threat.

"If there are changes in their distribution their foraging patterns, their communication patterns those can be important, those can be significant kinds of affects," says Southall.

Dr. Graham Kent has spent more than 25 years on boats conducting these types of surveys, most recently just last July.

"We used an array off of Washington State that was exactly twice as powerful as what is purposed off the Central Coast."

Kent says there were no casualties of marine life during that research and insists that these surveys do not physically harm animals.

"I think if a lot of people went out on a seismic boat and saw how we interact with the National Marine Fisheries and the marine mammal observers, how we shut down when we need to, I think people would feel a little bit better."

After almost nine months of constant research from scientists worldwide, there is still no clear cut answer to what killed those thousands of dolphins off the waters of Peru.