How loud is the sound of a breaching whale?

The sound levels of breaching whales can be found in published literature.  In a paper published by APPEA, and based on published information, we can see on page 4 that the sound level of a breaching whale is quoted as 200dB re 1 micro Pascal at one metre from the source (ie extremely close to the whale itself!).  In the same APPEA publication the sound of a seismic acoustic source is quoted as 230-255dB re 1 micro Pascal at one metre.  The sound level obviously depends on the size of the source so, if we take a mid-range source (242dB) we can calculate that the sound of a seismic array at 128m is the same as a whale breaching at 1m.  NB. This attenuation is calculated using the physical principles of sound attenuation in water!  Thus, it’s little wonder that humpbacks are often seen well within the 500m shut-down zone (and certainly within the 2000m power-down zone) contained in EPBC Act Policy Statement 2.1.

We are fortunate to have available to us, courtesy of Associate Professor Rob McCauley of Curtin University Centre for Marine Science and Technology, the sound of a breaching humpback off the NW Shelf of Australia compared to the sound of a seismic array:

Comparison of sound energy levels of humpback breaching and seismic source

Comparison of sound energy levels of humpback breaching and seismic source

Of course, even though these sounds are the same intensity, many people will note the very large difference in distance. That is 100m versus 6800m, a difference of 6700m.  However, bearing in mind the very rapid attenuation of sound in water in the near-field, using physical principles of sound attenuation in water, it can be demonstrated that the sound intensity of a humpback whale breaching at 1m is the same as this 2678 cui seismic array at 68m.

Perhaps that is why personnel on operating seismic vessels often see whales in close proximity to the operation as shown by the following photo of a humpback whale “up close and personal” with an operating seismic array offshore West Africa.

Humpback whale and seismic array

Humpback whale and seismic array

When one considers the facts, surely the conclusions must be different from the claims espoused by eNGOs and the precautionary management measures imposed by most regulators around the world?

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  1. […] generated at source by whales or natural processes. For example, as shown in articles on this site, the sound of a breaching humpback whale is the same as a seismic pulse at 68m and the sounds of calving/colliding icebergs are similar to […]

  2. […] from a normal seismic pulse as shown in an article on this website comparing a seismic pulse with the sound level of a breaching humpback whale. This means that primary sound exposure in this study was for 50% of the time (1.5 seconds duration […]

  3. […] marine environment is actually a very noisy place as a result of biological sounds (vocalisations, breaching, etc) and natural sounds (cracking/colliding icebergs, earthquakes, lightning strikes, etc).  […]

  4. […] whales live in a noisy ocean where there are natural sounds such as calving/colliding icebergs and sounds from their own activities that are similar in intensity, frequency and periodicity to seismic […]

  5. […] icebergs generate sounds of similar loudness, frequency and periodicity and whale calls and breaches are at similar levels to those within a few hundred metres of a seismic […]

  6. […] environment?  In any case, biological and other natural sounds, including their own vocalisations, their breaching and icebergs calving/colliding (in their feeding grounds!) are as loud as seismic sounds!  Why has […]

  7. […] Furthermore, seismic sounds are no different from many common natural sounds in the ocean, including humpback breaching and the sound of calving/colliding […]

  8. […] and the science tells us why.  Much of this science, such as other sounds in the ocean, the sounds of breaching whales, Antarctic ice sounds, the reaction of cetaceans to seismic sounds, attenuation of sound in water, […]

  9. […] A clear example of the manner in which eNGO protests are far moved from reality can be seen in the following photo and the article “How loud is the sound of a breaching whale?“: […]

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