Seismic Air Guns for Oil Exploration: Impact on Marine Life

seismic air gunsOn Thursday, the Bureau of Ocean Energy Management released an Environmental Impact Survey, three years in preparation, assessing a proposed project to use seismic air guns for exploring the offshore oil and gas resources beneath the U.S. Atlantic outer continental shelf range, and proposing mitigation measures to diminish the impact on marine life.

The energy industry says potentially vast reserves lie in the depths of the Atlantic, but they claim these could be uncovered only by seismic surveys, performed by towing seismic air guns blasting extremely loud sounds down to the seabed to detect the size and location of hydrocarbon deposits.  Environmental groups say the use of this technology will have a devastating effect on marine wildlife, especially threatening to populations of right whales, with humpback whales, dolphins, and loggerhead turtles being impacted as well.

Obviously an issue like this is extremely contentious, with emotions running high on both sides of the question, pitting as it does, the vast financial reserves of the fossil fuel industry against animal rights activists and environmentalists.  People who are ambivalent about this technology may be wondering how to realistically get an answer from a whale about the damage caused by the seismic air guns.  Without knowing anything about oceanography, or cetacean behavior, the average newsreader is left to form an opinion on the basis of gut feelings.  Gut feelings, however, are not the most solid evidence on which to base policy.

So here are some questions that one might pose, in order to gain a better understanding.

First, exactly how loud are seismic air guns really? The air guns produce a sound measured at 190 dB.  For comparison, the sound of a motorcycle shredding the air down your block comes in at 100dB.  A jet engine lets off 140dB of noise.  It should be noted that loudness is measured on a logarithmic scale; each 10 dB increase is a ten-fold increase in power.  Thus, the air guns are a staggering one billion times louder than that irritating motorcycle.  Furthermore, because the sounds generated by the seismic air guns propagate through marine water, the sound is approximately 63 dB louder than a sound with the same intensity in air.  That means six more zeros need to be appended to that billion, turning it into an unimaginably loud quadrillion times louder than the motorcycle.  Now imagine that a noise that unpleasant is being repeated every 12 to 16 seconds, for up to 24 hours at a time, for weeks or months.  Who would be a whale?

Two, how does oceanic noise pollution affect marine life, and how large an area is affected?

Because a numerical analysis cannot quite convey the subjective experience of being anywhere near something that loud, one needs to turn to available published reports on how this technology will affect marine life.  According to the National Resource Defense Council, ongoing research indicates that noise pollution in the ocean negatively impacts at least 55 marine species, including several endangered whale species and 20 species of commercially valuable fish.  Whales and dolphins rely on their hearing to find food, communicate, and reproduce, thus being able to hear critically affects their survival.  The use of seismic air guns has been shown to affect animals in an area of more than 100,000 square nautical miles.  For an understanding of how huge this is, if 100,000 square nautical miles were centered over Washington DC, it would extend from the northern edge of New Jersey to the middle of North Carolina, covering two thirds of Pennsylvania, all of Maryland, and a large chunk of Virginia.

Exactly which species are threatened and in what way? Marine life is far too diverse and complex to make a realistic assessment of all the possible ramifications of the use of the air guns.  However, research from NOAA and Cornell, indicates that one of the most vulnerable is the critically endangered North Atlantic right whale – of which only 400-500 individuals survive –  whose calving grounds off Florida and Georgia would be directly impacted by the proposed survey.  Airguns have also been shown to affect a broad range of other marine mammal species including sperm whales, whose foraging appears to decline significantly on exposure to even moderate levels of airgun noise.  Harbor porpoises have been observed engaging in strong avoidance responses as far as fifty miles from a seismic array.  Seismic surveys have also been found at fault for long-term loss of marine mammal biodiversity off the coast of Brazil.  Seismic air guns kill larvae and fish eggs and cause declines of 40 to 80 percent in the catch rates of haddock and cod areas up to thousands of miles away. Beyond the environmental considerations and the effects on marine mammals, the decline in catch rates of commercial fish has a strongly negative economic impact; fishermen in some parts of the world have begun to seek industry compensation for their losses.

And finally, despite all the already available information on the impact of oceanic noise pollution, not all the facts are in yet.  The National Marine Fisheries Service (NMFS), a division of NOAA, is completing a 15-year research program gathering information on how marine mammals are disturbed and damaged by sound.  Last week, a group of more than 100 scientists wrote to Obama urging him not to finalize the Environmental Impact Study until the latest marine mammal acoustic guidance is available.

So, who is on the other side of this issue?  Well, the oil industry, primarily.  That, and a number of Southern governors, who say offshore drilling could bring new jobs to their states.  Nine companies have applied for permits to use the seismic air guns to determine how much fossil fuel lies beneath the water off the Atlantic coast from the mouth of Delaware Bay to just south of Cape Canaveral, Florida.

Worse yet, an estimate of the undiscovered oil and gas resources beneath the U.S. Atlantic outer continental shelf range already exists.  Government estimates put the possible stores at 1.3 to 5.58 billion barrels.  But energy industry officials want to undertake a new study using the seismic air guns, claiming that the last energy exploration of the offshore Atlantic which occurred in 1988, was performed with equipment that is now outdated.

According to Erik Milito, director of upstream and industry operations for the American Petroleum Institute (API), drilling in the Atlantic could add “1.3 million barrels equivalent per day to domestic energy production…”

BOEM Director Tommy Beaudreau indicated a commitment to balancing the need for information on offshore energy resources with the protection of the human and marine environment.    The EIS estimated “minor to negligible” impact to most wildlife, with a “moderate” impact on marine mammals and turtles. The review estimates approximately 138,000 marine animals could be injured, and the feeding, migratory, and other behavioral patterns of 13.6 million other marine animals would be disrupted by the seismic surveys.

In the final analysis, these surveys are undertaken for the purpose of perpetuating dangerous and dirty offshore drilling, incurring possible habitat destruction, oil spills and contribution to climate change and ocean acidification. Exploration of the BOEM website shows that this organization is very committed to clean and renewable energy production, such as the “Smart from the Start” program to speed development offshore wind energy development off the Atlantic Coast.  Other programs include development of wind, wave, current, and solar energy; and alternative uses for offshore oil and gas platforms such as research, education, recreation and offshore aquaculture.  All of which, going with a gut feeling, will probably be much cleaner, healthier, and ultimately more economically sound, than dragging out the protracted demise of the fossil fuel industry by insisting on the use of seismic air guns to perform noisy, environmentally dangerous, and possibly unnecessary surveys.

by Laura Prendergast

National Geographic

Bureau of Ocean Energy Management

Washington Post

13 Responses to "Seismic Air Guns for Oil Exploration: Impact on Marine Life"

  1. Nerak   May 30, 2014 at 5:06 am

    No evidence Alex????? College educated??? RE -he -he ally?!?

  2. James Dean   March 3, 2014 at 2:27 pm

    I say crank it up louder to turn it into a new kind of fishing rig.

  3. Hank   March 3, 2014 at 4:53 am

    The author’s understanding of sound pressure levels is faulty. You can not compare measurements in air to those in water. A blue whale emits a 188+dB call at intervals of 180 seconds. Blue whales live in all the major oceans, but they are not damaging the worlds oceans. Get your facts straight.

    • Alex   March 3, 2014 at 6:00 am

      Agreed. Common sense indicates that since blue whales can talk to each other at nearly 190dB, then a 190dB airgun can hardly have a detrimental effect on whales and other marine life.

      What the author needs to realize is that scientists are just as prone to fear-mongering as she is. Fear mongering sells newspapers – it also generates more research dollars. Why not do an in depth study of how well-educated foolish people are easily taken in by stories of man harming nature, even when no evidence for such damage exists.

      Do know how many scientists “believe” in global warming just because other scientists say it is so? Probably 95% or more. Do you know how many college-educated people are appalled by the content of this article because they think it is all true (‘oh I am soo upset with humanity! The poor whales!)? All of them. And how many have studied the evidence? None. Did the author? Barely to no.

      Biggest killers of whales and other marine mammals in history? Fishermen, other marine life, and old age.

  4. In the Know   March 3, 2014 at 3:57 am

    This article is full of mis-information and fear mongering. If air guns damaged marine life, we would have been hearing about it for decades, with dead whales floating about behind every seismic ship. Well-meaning, but completely idiotic nut-jobs are fueling this issue with reckless abandon and are spreading what amounts to lies. The author completely mis-represents sound pressure levels in water (confusing numbers with those derived in air) and fails to tell you that Blue whales emit calls at ~185-190 db underwater. If air guns are killing off marine life, then so are blue whales. By the authors measure, Blue whales are the biggest source of environmental sound damage in the oceans (more blue whales calling than seismic air gins popping).

    I hope the author does her homework and then dies of embarrassment.

  5. Jim   March 2, 2014 at 9:46 pm

    Well, Spud, the article doesn’t specify if the air gun dB was measured in air or water. My guess is that it was a water measurement, since that is the environment the guns are designed to operate in. If that’s the case, I guess you could subtract your 62dB from all the airborn sounds referenced in the article. But, that’s really not the point. We are inhabitants of Earth, as is the wildlife. We depend on that wildlife for survival, yes, really! Sure, its nice to have gas in the car, its nice to have a job, but its also nice to be a good neighbor. If I moved next door to you and started auditioning punk bands in my driveway all hours of the day and night, you might not care that its my job, that its what keeps gas in my car. Do I have a right to disrupt the entire neighborhood in the pursuit of my personal goals? Man is an arrogant beast, he thinks he owns this planet and can do whatever he wants with it. But the planet is more valuable than any one of its inhabitants, including man. If you’re a bad enough neighbor, eventually your actions will get you kicked out of the neighborhood, and you’ll have only your self to blame. Disrupt the ecosystem, and there will be a backlash. The rich folks in the oil companies don’t care, the rich politicians don’t care. When the planet becomes toxic, they’ll live in little domes, because they’re rich, they can afford filtered air and bottled water. And if everyone else is starving, who cares? They’re rich, they can afford to eat, so what does it matter if the rest of us die? Really, what does it matter? At least when we’re all dead, we won’t need any more of their oil, then maybe the planet can get back to normal, without us.

    • Alex   March 3, 2014 at 5:42 am

      None of what you wrote has any bearing on the issue of airgun use in the oceans. Your anecdotal antics are meaningless. Learn something before spouting off – same goes for the author of this fear-mongering, fact-false article.

  6. Gitsie Depp   March 2, 2014 at 9:29 pm

    This article angers me because it is clear the author has no idea about seismic exploration. I currently work with a major seismic exploration company on a seismic vessel. We have workers who watch for marine life as well as those who listen for marine life at night. Anytime marine life is within ~1/3 of a mile (~500 m) radius from the air guns, the air guns are shut down. Once the marine animals have moved outside of that zone, the guns are started up slowly to give any other animals time to clear out. This is standard procedure for most legitimate seismic exploration companies. The authors “gut feeling” might be negative, but we should be considering facts when making decisions about issues, not feelings.

  7. Kevin   March 2, 2014 at 8:50 pm

    Jerry, I am sorry to hear about your tinnitus, but don’t jump to any conclusions quite yet about the whales suffering from the same. The author has made a seriously flawed comparison between sound pressure levels (SPL) in air and water. I ride a (quiet) motorcycle and appreciate the attempted analogy, but the notion that these seismic surveys sound like a billion — no, a quadrillion! — motorcycles roaring down the street is just plain wrong. The author says this is unimaginably loud; indeed, it is unimaginable. The problem here (and a common one, unfortunately, in this context) is with the understanding of the decibel and its use in non-scientific writing. It is widely misunderstood and misrepresented. The decibel is a logarithmic quantity describing one value (say, a sound pressure level!) RELATIVE to some other reference value. That reference value can be whatever you want it to be. For instance, I had 10 dB spoonfuls of oatmeal relative to 1 spoonful of oatmeal for breakfast this morning. When it comes to reference values for sound pressure levels, like those which have clearly been ignored in this article, acousticians have chosen 20 micropascals in air and 1 micropascal in water. The important point here? For the same acoustic pressure (regardless of the medium), any SPL measurement in decibels relative to the ‘air’ reference pressure is going to be much lower than that relative to the ‘water’ reference pressure. This makes for scary numbers when someone tries to compare a sound pressure level in water to some sound in air (like a motorcycle) with which humans might be more familiar. The decibel values ‘in water’ are much larger than those ‘in air’ because the REFERENCE pressures are an order of magnitude different! Do the math. The larger number ‘in water’ is not a simple multiple of a lower number ‘in air’ and, in this case, most certainly does not equal a quadrillion. Sometimes I wonder if the meaning of the decibel is willfully ignored or concealed in this type of writing because it is so useful for making emotional and outrageous comparisons. I’m not saying that air guns and jet engines are quiet; but I do certainly stop reading pieces like this after seeing such fundamentally flawed comparisons. If the author can explain the decibel to their reader to ensure a more reasonable analogy, I’ll be happy to finish the article.

  8. John Herman   March 2, 2014 at 8:42 pm

    190 dB in water is approximately 50 Watts. There are a lot of things in the ocean that generate more power than this. Several varieties of whales produce sound power in this range One variety of whale produces sound at 214 dB which is used to stun its prey so that might not be a good example.

    If you subtract 100 dB from the SPL in water, you would arrive at a roughly comparable SPL in air.

  9. Teresa Smith   March 2, 2014 at 8:19 pm

    I spent an entire summer on one of these seismic vessels in the Gulf of Mexico when I was in college. I agree that more research needs to be done on the impact of air guns on sea life, but I can share what I observed directly. First of all, the air guns are designed to shoot the sound waves straight down. Energy going out in all directions is energy wasted and the best reflections of the subsurface come from sound waves hitting the seafloor vertically. Second, on the surface, you hear a dull boom each time they go off, kind of like when you hear fireworks from the next town over. It might be louder underwater, but it’s definitely not loud at the surface. (The guns were towed below the surface, maybe 100 yards behind the boat.) Third, those goofy dolphins! They played in the bow waves and accompanied our boat on many, many occasions, even while we were shooting. Either they were protected from the noise by hanging out at the bow, or it wasn’t bothersome enough to overcome their curiosity. We did see whales on occasion, but at a distance.

  10. Spud Coolzip   March 2, 2014 at 7:51 pm

    While those sound levels are generally accepted as being devastating to wildlife, the numbers presented for comparison are for sound pressure level (SPL) in air, not water. In order to compare those levels in terms of audibility and hearing damage, underwater SPL needs to have 62dB subtracted from it. Those 190dB guns would sound like 128db at the same SPL in air – still plenty strong to damage the eardrums of any animal, but not the concrete-pulverizing level claimed in this article.This is a common mistake made when presenting this issue to the public.

    More info at

  11. JERRY   March 2, 2014 at 7:09 pm

    I have acquired permanent Tinnitus from listening to an uncontrolled loud music CD input into my music software recently. I, stupidly, left my headphones on for about 3 minutes as I tried to lower the sound instead of whipping my phones off.
    The description above of the sound levels of the air gun is , indeed, unimaginably shocking and inhumane toward the animals in the water which would certainly have Tinnitus and PERMANENT loss of hearing at those ungodly levels. How sad! Every 10 seconds,24/7 ???!!!


Your Thoughts?