National Geographic News
From left, Virginia Aquarium Stranding Response Team members Krystal Rodrique of Virginia Beach, Va. and intern Liz Schell of Durango, Co. record observations of a deceased male dolphin on Ocean View Beach in Norfolk, Va. on Thursday, Aug. 1, 2013. This was their third dolphin retrieval of the day.  Officials are trying to determine the cause of a sharp increase in dolphin deaths in Virginia and other East Coast states. Five beached dolphins were found in Virginia alone on Thursday. In July, nearly four dozen dead dolphins were found, mostly in Norfolk and along the southern part of the Chesapeake Bay. That's up from the typical six or seven usually picked up in July by the Virginia Aquarium Stranding Response Team.  (AP Photo/The Virginian-Pilot, Dorothy Edwards)  MAGS OUT

Trained responders examine a dead male dolphin on Ocean View Beach in Norfolk, Virginia, on August 1.

Photograph by Dorothy Edwards

Christine Dell'Amore

National Geographic

Published August 21, 2013

The spike in bottlenose dolphin deaths this summer is showing no signs of stopping: Nearly 300 of the marine mammals have died along the East Coast as of August 20, according to the federal government. (Related: "Why Are Dolphins Dying on East Coast? Experts Alarmed.")

The high death toll, covering an area that stretches from New York to Virginia, has been labeled an "unusual mortality event," and the U.S. National Oceanic and Atmospheric Administration (NOAA) has experts scrambling to figure out what's going on.

Based on the rapid increase in dead bodies washing ashore, and the broad geographic reach, "an infectious pathogen is at the top of the list of potential causes," according to NOAA's website.

"We realize that people are very concerned and anxious to learn what we know about the dolphin deaths that have been occurring along the mid-Atlantic coast over the past few weeks," Maggie Mooney-Seus, a spokesperson for NOAA Fisheries, told National Geographic by email.

Experts have collected quite a bit of information from various animals' blood and tissue samples, which they're testing for a variety of toxins, biotoxins, bacteria, fungi, and viruses, she said.

Several of the dead dolphins have tested positive for morbillivirus, a measles-like, airborne virus that's often fatal in dolphins. A morbillivirus epidemic hit East Coast bottlenose dolphins in 1987 and 1988, wiping out at least 900 animals and striking a major blow to that population of migratory mammals. However, there's no definitive cause yet, and some of the tests take weeks to complete, Mooney-Seus noted.

"We share the public's desire to get answers to what is causing this and are working as quickly as we can to get those answers."

Determining a Cause of Death

The spike follows a general trend in unusual mortality events that have occurred in recent decades in the United States.

In the northern Gulf of Mexico, for instance, where there's an ongoing unusual mortality event, over a thousand dolphins and whales have washed up dead since February 2010. (Also see "Dolphin-Baby Die-Off in Gulf Puzzles Scientists [2011].")

The "concern is we're doing more and more to protect dolphins from harm, yet dolphin strandings are on the rise," Matthew Huelsenbeck, a marine scientist at the nonprofit Oceana, said earlier this month.

"No one seems to have a solid grasp as to what's going on."

But many are working to find out. For example, NOAA has a stranding network of experts who report and collect the corpses of recently deceased dolphins in an effort to determine causes of death.

A corpse is first taken into the lab for evaluation and basic triage to see if it has any visible marks that may point to the cause of its demise. Next, a tissue sample is taken and tested for viruses, which could identify a direct cause.

Then there's a longer-term investigation that involves testing blubber and organs, such as kidneys, for traces of heavy metals. Studies have shown that stranded dolphins have heavy metals in their systems.

"Dolphins are some of the most toxic animals on the planet, and it makes their immune system compromised because they're carrying so many heavy metals and toxins that accumulate in the food web," noted Huelsenbeck. (Also see "New Diseases, Toxins Harming Marine Life.")

He also noted that the dead bodies that wash ashore are only a small percentage of the actual death toll. For instance, many dolphin corpses decompose at sea or are eaten by predators.

"For a lot of these animals," he said, "their story will never be told."

k k.
k k.


MAN is responsible for such mystery.

Peace Seeker
Peace Seeker

Naval sonar is destroying mammalian oceanic life! Literally, it is bursting the auditory canals of whales and dolphins! There is shocking evidence of what sonar can really do to mammals that call the ocean their home. Join marine biologist Antonella Servido and watch for yourself as she devotedly investigates the mystery of the Canary Island pilot whales. Why is it that an increasing number of these beautiful animals are becoming fatally stranded? There is concern that the ever-increasing ocean noise (naval sonar PING) is interfering with the communication of these acoustically sensitive animals. Can the military sonars, which have been employed to detect hostile submarines, be responsible for the multiple deaths of the pilot whales and other mammalian ocean life?

陈 亚 雄
陈 亚 雄

We should do something,or we will lost something,something important~

Robert Taylor
Robert Taylor

Absolutely no chance this is a natural phenomenon. Likely climate change is involved.  Obviously there are significant contributions from disintegrating plutonium tanks, bad karma from Taiji Japanese dolphin murderers, naval sonar, agricultural chemicals, and I can't believe no one else has mentioned the obvious: hydraulic fracking.  I am not surprised as I watch the human race's relentless march to destroy every living thing and even our beloved Mother Earth herself!

This is what embracing the so called theory of evolution and the homosexual agenda is bringing to the greatest country on earth. God willing, we will prevail, in peace and freedom from fear and in true health, through the purity and essence of our natural fluids.

Jacqueline H.
Jacqueline H.

Has anyone considered the tanks of plutonium that were buried up and down the coast during the war?  The tanks are above a fresh water table and have been disintegrating for years FOR FACT in Florida.  They can not be moved nor can be disposed.  What do you suppose is happening?  

Our species is destroying life.  


Marilyn Stonebraker
Marilyn Stonebraker

Look up Taiji Japan dolphins and see how they slaughter them by the thousands in one year.  They are the bottlenose and also pilot whales that they are killing.  Faroe Islands kill  thousands of pilot whales a year.  Namibia kills tens of thousands of cape fur seals a year.  The killing has to stop because you never know when a virus could really wipe out a population.  Hopefully National Geographic can do articles on this massive killing of sea mammals every year by these countries.

craig hill
craig hill

WHY is this kind of thing constantly a shock when THE OCEANS ARE DYING AND WE ARE ITS MURDERERS.

Adam King
Adam King

I would wonder if run off chemicals from the flooding/storms this past year (including Sandy) have caused a pathogen to form, or at least contributed to this issue. Obviously only speculating, but there would have to be a significant event and/or alteration that contributed to this. 

M Patterson
M Patterson

I would want to know if there has been recent Naval sonar testing in the area(s).   

Korinna Domingo
Korinna Domingo

@Robert Taylor Are you serious? "This is what embracing the so called theory of evolution and the homosexual agenda is bringing to the greatest country on earth. "

Pain Hurts
Pain Hurts

@M Patterson I would laugh at anyone who denied it. And they are probably testing as I write this.


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