A Pulsing Sea – The Effects of Seismic Airguns on Whale Populations

Updated 04/04/2019

Whales are notoriously vocal animals. Indeed, the catalyst for the ‘Save the Whales’ campaign of the 1970s can be said to be the release of the album ‘Songs of the Humpback Whale’ recorded by bio-acoustician Roger Payne. This was the first time that the public was able to hear and appreciate the astonishing variety and beauty of the Humpback’s songs. This love affair with the whales came in the nick of time, since the humpback population had at that time fallen to a historic low. It is estimated that by the late 1960s, over 90% of humpbacks had been wiped out by human activity.

Since the early 1920s, a technique known as ‘reflection seismology’ has been used to locate reserves of natural resources such as oil, gas and salt. Reflection seismology operates on much the same principle as sonar. Sound waves are emitted which reflect off the sea floor and are then measured by an array of sensors. Using this technique, areas of the sea floor can be accurately mapped, and it is possible to determine whether natural resources lie beneath the rock.

Modern reflection seismology is carried out using huge arrays of seismic ‘airguns’. These airguns can produce sounds of up to 240 decibels, over twice the volume of a standard rock gig. What’s worse, this noise level is produced every 10 seconds, 24 hours a day. According to Oceana, a single survey ship may carry up to 96 airguns at a time. 

Whales and dolphins use sound to communicate with each other and, in some cases, for the echolocation of prey. Although insufficient research has been conducted to ascertain the detrimental effects of seismic testing on whales, preliminary data shows that almost all cetaceans give seismic airguns a wide berth. Further, sightings of cetaceans fall significantly when seismic testing is being conducted in a given area.  Even in the absence of solid data, mere common sense dictates that the levels of noise produced by seismic testing may well prove to seriously harm the hearing of cetaceans, as well as disrupting their feeding, mating and migratory habits. In any case, if reflection seismology is at all likely to damage already strained marine environments, it is imperative that we halt that practice before the damage is irreversible. 

It is not just whales that are at risk. During periods of seismic testing, local fishermen have reported an increase in dead fish floating in the sea. Squid, crabs and fish eggs have also been shown to be harmed by seismic airguns. It seems, then, that as well as deafening and disorienting endangered whales, seismic testing is also harming their ecosystem and thus limiting the availability of their prey. One study found that the number of zooplankton – tiny creatures that are the backbone of marine ecosystems – fell by 64% within 1,219 meters of airgun activity. That is guaranteed to have huge knock-on effects not just for whales and dolphins, but for all ocean life. 

On the 1st of February 2018, seismic airgun testing off the coast of Newcastle, Australia was approved by NOPSEMA. The tests, which will be carried out by Asset energy, are approved right up until the 31st of May, with the whale migration set to begin around the 1st of June. This has been met with serious resistance. Greenpeace Australia campaigner Nathaniel Pelle noted that “Whales and other endangered species do not adhere to the Gregorian calendar and do not know the difference between May 31 and June 1”. The fact that this must be noted at all speaks to the greed and short-sightedness of regulators and fossil fuel companies.

In December of 2018, the U.S. (under the command of Donald Trump) began extensive seismic surveys of the entire east coast. This happened despite vehement opposition from almost all U.S. environmental agencies and state governments. The area which the U.S. has begun to survey is the home and breeding grounds of the North Atlantic Right Whale, a species so endangered that there are less than 500 of them alive today. 

A final and crucial point to consider is that even if seismic tests did not damage marine populations directly (which they certainly do), they are a gateway to offshore drilling, a practice which damages marine populations in a number of ways. First, there is a possibility of oil spills which, as we all know, can be cataclysmic events for marine ecosystems. Further, when the oil is successfully extracted, it will be burned as fuel, releasing carbon dioxide into the atmosphere and accelerating the already severe effects of climate change. Renewable energy sources such as wind, solar and wave energy are the planet’s last hope for any sort of meaningful recovery. One may consider it an added bonus, then, that these energy sources do not require that we seriously harm marine species while they attempt to recover from the immeasurable damage that humans have already inflicted upon them.

Sources

Beachapedia – Seismic Surveys

Bielby, Nick – NOPSEMA accepts environmental plan for seismic testing off Newcastle coast and Concern over plan for seismic test off the coast of Newcastle

Gordon, Jonathan C.D et al. – A Review of the Effects of Seismic Survey on Marine Mammals

Greenpeace Australia – Humpback whale migration threatened by seismic blasts

Hannam, Peter – ‘Whales don’t follow the Gregorian calendar’, opponents of seismic testing say

Stone, Carolyn J. and Tasker, Mark L. –  The effects of seismic airguns on cetaceans in UK waters

Photo Credit: Maui Magic

2 Comments on “A Pulsing Sea – The Effects of Seismic Airguns on Whale Populations

  1. I looked up the sound limit’s it is 120db for children or140db for adults. The figure you give for the sea is 240db which is 100db higher x100 times (10^10) higher power. If it were double then the sea would be 143db (which figure is correct)

    Like

    • Hi Andrew, thanks for commenting!
      The figure of 240db refers to the loudest sounds known to be made by seismic airguns. Hope that’s answered your question

      Like

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