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In what researchers and officials are referring to as mysterious incident, over 800 dolphins have washed up on the northern shores of Peru between mid-February and mid-April. A news report on CNN aired earlier today said over 1,000 have now been confirmed, but this video does not appear to be online yet.

The carcasses, many already badly decomposed,  were difficult to examine yet certain causes have already been ruled out while others are believed to be the likely cause. Environmental authorities have already singled out a viral or bacterial component as the likely cause, with only the large count of dead as the implicating factor in this theory.


[Deputy Environment Minister Gabriel] Quijandria said Thursday that 877 dolphins have washed up in a 220-kilometer (137-mile) area from Punta Aguja to Lambayeque, in the north of the country.

The dolphins may have died from an outbreak of Morbillivirus or Brucella bacteria, said Peruvian Deputy Environment Minister Gabriel Quijandria, according to Peru's state-run Andina news agency

More than 80% of those dolphins were found in an advanced state of decomposition, making it difficult to study their deaths, according to Andina.

Officials have been able to conclude that the dolphins' deaths were not due to lack of food, interaction with fisheries, poisoning with pesticides, biotoxin poisoning or contamination by heavy metals.

The results of a histopathological analysis -- which would indicate possible contamination by a virus -- are expected to be ready in the coming days.

So they have speculated on a cause, based on the size of the die-off, and now they are awaiting lab results that should confirm or rule out their hypothesis.

Seismic expoloration has been unequivocally ruled out.

Deputy Environment Minister Gabriel Quijandria told The Associated Press in an interview on Friday that studies are incomplete but officials hope to complete their research on the likely causes next week.  He said that the carcasses of 877 dolphins and porpoises were found between February and mid-April on the beaches of northern Peru.

He said officials don’t believe the dolphins’ deaths are related to seismic oil exploration work that was carried out off northern Peru between Feb. 8 and April 8 by the Houston-based company BPZ Energy.

Rafael Zoeger, the company’s manager in Peru, said the seismic studies were carried out using a ship that fired discharges of compressed air toward the sea floor. It’s customary for oil companies to carry out such surveys with air-guns that emit sounds and send out underwater pulses. Zoeger said the company does not believe the dolphins died due to the oil exploration work.

But Quijandria said that “so far there is no evidence linking the deaths of the dolphins to the seismic work.”

So, let's review. The seismic exploration was conducted between February 8th and April 8th. Hundreds of dead dolphins (maybe as many as 1,000) subsequently wash up on shore between mid-February and mid-April. But there is 'no evidence' linking these two events. Well, if you're going to looking for a virus or bacteria with lab tests, it will make it difficult to find any evidence connecting the deaths to seismic exploration. Fortunately someone seems to think there's a connection.
The Peruvian environmental group Orca has said that sound waves from the seismic work appeared to be the likely cause.
Researchers elsewhere are studying the effects on marine mammals of the air-guns used in seismic studies. But George Ioup, a physics professor at the University of New Orleans, said “it’s pretty much an open question at this point... whether harm is caused to the animals.”
So it's unknown whether or not seismic exploration has any harmful effect on marine animals yet, without any studies, officials have been able to rule this out as a cause.

The CNN report referred to earlier (which I will post if it becomes available) had an interview with a marine biologist who said the auditory bone in these carcasses was found to be fractured and said one of the possible causes for such a large die-off could be a 'seismic event'.

For further enlightenment, here is some information on the exquisite sensitivity of the dolphin's auditory system.

'Dolphins possess a highly developed and intricate auditory system, perhaps the most developed of all auditory systems in the animal kingdom, considering their large frequency range of hearing and their ability to perceive very short signals in the range of on the order of tens of microseconds.  

The auditory system of dolphins seems to be adapted for processing complex acoustic systems.

And here is some information on seismic exploration and its role in drilling for oil.
Seismic exploration uses sound waves to determine the density. It can do this because sound waves will move differently through different material. When seismic exploration is used to explore for gas, the sound waves will move through the earth and the results are used to determine where the best place to drill will be. The sound waves can be used to create a 3D image of what lies below the surface. Just like a sonogram or MRI gives a 3D picture to make it easier to treat patients, a seismic 3D image of the material underground makes it easier to choose the ideal place to drill.

Seismic exploration is a major breakthrough for drilling for gas. It has made the drills more efficient and higher producing than before seismic exploration was possible. There are various ways that sound waves are sent into the ground. The most common is to use a truck with pads that vibrate, to send sound waves into the ground. The sound reflects back up and is received by devices called geophones. The geophones will then record the sound waves and transmit the information to a truck that records the information that is received.

For offshore exploration, ships are used instead of trucks. Seismic exploration is restricted in some areas during certain times of the year because it can interfere with marine life that uses sonar for navigation because it can interfere with breeding, feeding, and may contribute to them beaching themselves.

Well, I sure can't see how that could interfere with an animal that uses echolocation to get around the sea.
Dolphins rely heavily on sound production and reception to navigate, communicate, hunt, and avoid predators in dark or limited vision waters.
Perhaps these officials can do some basic research and unravel this mystery.



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Comment Preferences

  •  Greed is killing the oceans (15+ / 0-)

    along with everything else. We are a stupid species.

    Not this mind and not this heart, I won't rot • Mumford & Sons

    by jayden on Sun Apr 22, 2012 at 03:58:58 PM PDT

  •  Uh... just pointing out.... (8+ / 0-)

    ...that you left out some significant information which bolsters your case.

    From your link: seismic exploration

    For offshore exploration, ships are used instead of trucks. Seismic exploration is restricted in some areas during certain times of the year because it can interfere with marine life that uses sonar for navigation because it can interfere with breeding, feeding, and may contribute to them beaching themselves.
    BPZ was doing this with the imprimatur of the Peruvian government. Should it be found that the seimic testing was done during a time of known migrations of these dolphins and Peru knew it, then international sanctions and criminal charges brought where appropriate. Peru has a few laws on the books protecting marine mammal species, but they are basically showpiece legislation with no real teeth. Since BPZ is an American company. If they commit a crime on foreign soil (or waters) they can be tried in the American justice system. And it appears to me they have violated the Marine Mammals Protection Act.

    "Wealthy the Spirit which knows its own flight. Stealthy the Hunter who slays his own fright. Blessed is the Traveler who journeys the length of the Light."

    by CanisMaximus on Sun Apr 22, 2012 at 06:03:37 PM PDT

    •  Thank you (2+ / 0-)
      Recommended by:
      Cedwyn, OldDragon

      will update

      as far as migration, I can't really tell if / where this is a factor


      1. Variations in water temperature, movements of food fish, and feeding habits may account for the seasonal movements of some dolphins to and from certain areas.

      2. Some coastal dolphins in higher latitudes show a clear tendency toward seasonal migrations, traveling farther south in the winter. For example, coastal bottlenose dolphins on the Atlantic side of the U.S. migrate seasonally between New Jersey and North Carolina.

      3. Coastal dolphins in warmer waters show less extensive, localized seasonal movements.

      4. Some coastal animals stay within a limited home range: an area in which individuals or groups regularly move about during day-to-day activities.
      • Individual dolphins that live within a home range are called "local residents." Resident dolphins have been identified along the coasts of Georgia, Florida, Texas, southern California, Gulf of California, and South Africa.

      • Groups of dolphins that reside within a home range make up "resident communities." The Sarasota, Florida resident dolphin community home range is an area of about 125 km2 (48.3 mi2).
      • Home ranges may overlap.


      "I'm sculpting now. Landscapes mostly." ~ Yogi Bear

      by eXtina on Sun Apr 22, 2012 at 06:18:05 PM PDT

      [ Parent ]

  •  if it were seabirds and later in the year (0+ / 0-)

    it could be the shift from la niña to el niño, which leads to a die-off in fish in that area because of warm, nutrient poor water, but the dolphin thing is weird, and too early to be el niño anyways.

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