Seismic surveying and Impacts on Cetaceans: an EIA perpective

The Arctic Ocean and surrounding waters are home to a number of whale species. Blue whales, Minke whales, belugas, right whales, and endangered fin whales either make these areas their homes or feed there seasonally. Feeding grounds are of great importance to migrating whales, as they require massive amounts food before moving on to breed in warmer waters. A growing threat to whales is that of marine noise. Sources of noise include commercial ships, military sonar use, and gas and oil drilling and exploration (NRC, 2003).

Offshore oil drilling has been a hotly debated topic, particularly in the United States, but is equally important in Canada. Oil exploitation projects are subject to comprehensive environmental impact assessments, and a number of these have been undertaken under the auspices of the Canadian Environmental Assessment Act. An overview of these studies shows that impacts on whales and other marine mammals were either uncertain due to a lack of knowledge, or predicted to be minor. When it came to noise impacts, only longer term shipping, drilling and operating noises were considered during the EIA process (CEAA, 2011). The EIA process does not include seismic exploration as a factor for noise impacts. Exploration however is a major source of noise, and the exploration phase of a project can last up to 9 years (CEAA, 2011).

Here’s a quick video of how seismic surveying works.

When they talk about acoustic source arrays in the video, what they mean is giant airguns firing sounds of over 240 dB into the water (NRC 2003). Some countries have implemented noise level standards for the airguns used in seismic testing. For example, the National Environmental Research Institute of Greenland recommends threshold levels for seismic surveying of 230 dB, well above those of the American EPA (180dB), with the justification that according to recent studies sound levels are well below levels that would cause permanent auditory damage to cetaceans, unless they are in the immediate vicinity of the firing airgun (Boertmann, D. et al. 2009). These guidelines completely ignore the more significant impacts that noise can have on marine mammals over the short and long term.

Exposure to noise has been found to change calling patterns of right whales, which can hinder pod cohesion as well as feeding and mating behaviour (Parks et al. 2007). Whales have also exhibited avoidance behaviour, which can lead to bypassing important feeding grounds and generally reducing the fitness of those affected populations over time (Weilgart, 2007; Tyack, 2008).

Seismic testing should be included in any Impact Assessment of oil and gas exploitation projects.At the very least stringent standards on how and when it can be done should be implemented. Seasonality considerations are important. The warmer months in the arctic are when the waters are the most navigable, and so best for testing, but it is also the same period of time that some whales will be feeding and migrating, increasing their exposure to noise.

Gas and oil companies believe that their practices are safe and sound, and won’t likely change their practices unless forced to do so by law. See here how a BP America executive testifies before a senate committee:

Sometimes testimonies aren’t very distinct from jokes:

References:

Boertmann, D., Tougaard, J., Johansen, K., Mosbech, A. 2009. Guidelines to environmental impact assessment of seismic activities in Greenland waters. National Environmental Research institute, Aarhus University, Denmark. NERI Technical Report no. 723.

Canadian Environmental Assessment Agency (CEAA). Evaluation of the ClimAdapt Guide to Incorporating Climate Change into the Environmental Impact Assessment Process. Accessed November 14, 2011. http://www.ceaa.gc.ca/default.asp?lang=En&n=332BCF7D-1

Committee on Potential Impacts of Ambient Noise in the Ocean on Marine Mammals, National Research Council (NRC). 2003. Ocean noise and marine mammals. Accessed November 10, 2011. http://www.nap.edu/catalog/10564.html

Parks, S.E., Clark, C.W., Tyack, P.L. 2007. Short- and long-term changes in right whale calling behaviour: the potential effects of noise on acoustic communication. Journal of the Acoustic Society of America. 122(6), December, 3725-3731.

Tyack, P. 2008. Implications for marine mammals of large-scale changes in the marine acoustic environment. Journal of mammalogy. 89(3):549-558

Weilgart, L.S. 2007. A brief review of known effects of noise on marine mammals. International Journal of Comparative Psychology. Vol. 20, 159-168.

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