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Soundings Archive

NMFS Seeks Public Comment on Shell Arctic IHA
NMFS has requested public comment on an application from Shell Gulf of Mexico Inc. (Shell) for an Incidental Harassment Authorization to take marine mammals, by harassment only, incidental to a marine surveys program in the Chukchi Sea, Alaska, during the open water season of 2013. Comments are due to NMFS by June 13, 2013, on this IHA which is proposed under the Marine Mammal Protection Act.

NMFS' Federal Register notice of this IHA contains some notable statements by NMFS, including the following:

"There is no specific evidence that exposure to pulses of airgun sound can cause PTS in any marine mammal, even with large arrays of airguns."


"To date, there is no evidence that serious injury, death, or stranding by marine mammals can occur from exposure to airgun pulses, even in the case of large airgun arrays."


"The estimated takes by harassment is calculated in this section by multiplying the expected densities of marine mammals that may occur near the planned activities by the area of water likely to be exposed to impulse sound levels of =160 dB (rms) re 1 µPa and nonimpulse sound levels =120 dB (rms) re 1 µPa. marine mammal occurrence near the operation is likely to vary by season and habitat mostly related to the presence or absence of sea ice. Although current NMFS' noise exposure standards state that Level B harassment occurs at exposure levels =160 dB (rms) re 1 µPa by impulse sources and exposure levels =120 dB (rms) re 1 µPa by non-impulse sources, there is no evidence that avoidance at these received sound levels would have significant biological effects on individual animals. Any changes in behavior caused by sounds at or near the specified received levels would likely fall within the normal variation in such activities that would occur in the absence of the planned operations. However, these received levels are currently used to set the threshold for Level B behavioral harassment."
  • Click here to read NMFS' Federal Register notice
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