NMFS Finds No TTS or PTS in Free-Ranging Marine Mammals Exposed to Seismic Airguns

NMFS received an application from Furie Operating Alaska LLC (Furie) for a Incidental Harassment Authorization (IHA) to take marine mammals, by harassment, incidental to a proposed 3D seismic survey in Cook Inlet, Alaska, between May 2014 and May 2015. Pursuant to the Marine Mammal Protection Act , NMFS requests comments on its proposal to issue an IHA to Furie to take, by Level B harassment only, six species of marine mammals during the specified activity.

NMFS states in the Federal Register notice of this proposed seismic IHA: “Researchers have studied TTS in certain captive odontocetes and pinnipeds exposed to strong sounds (reviewed in Southall et al., 2007). However, there has been no specific documentation of TTS let alone permanent hearing damage, i.e., permanent threshold shift (PTS), in free-ranging marine mammals exposed to sequences of airgun pulses during realistic field conditions.”

Comments to NMFS on this proposed IHA are due on or before  April 3, 2014.

Click here to read NMFS’ Federal Register notice.


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  1. Seismic Exploration

    The Oil and Gas industry takes a series of precaustions to protect marine mammals:
    The Oil and Gas industry has demonstrated the ability to operate seismic exploration activities in a manner that protects marine life. Marine seismic exploration is carefully regulated by the federal government and managed by the operator to avoid impacting marine animals.

    Four decades of world-wide seismic surveying activity and scientific research related chiefly to marine mammals have shown no evidence that sound from seismic activities has resulted in physical or auditory injury to any marine mammal species. Likewise, there is no scientific evidence demonstrating biologically significant adverse impacts on marine mammal populations.

    Nevertheless, the industry implements mitigation measures to further reduce the negligible risk of harm to marine mammals.
    Mitigation measures are standard operating procedures designed to minimize impacts to marine life.

    Trained marine mammal observers are onboard to watch for animals. Operations stop if a marine mammal enters an “exclusion zone” around the operation and are not restarted until the zone is all-clear for at least 30 minutes.

    When starting a seismic survey, operators use a ramp-up procedure that gradually increases the sound level being produced, allowing animals to leave the area if the sound level becomes uncomfortable.

    The current state of science and research:

    Peer-reviewed science and research suggest no evidence of injury to marine mammals as a result of sound emitted during seismic surveys.

    Based on both available scientific knowledge and operational experience, there is no evidence to suggest that the sound produced during an oil and gas industry seismic survey has resulted in any physical or auditory injury to a marine mammal.

    Research studies and operations monitoring programs designed to assess the potential impacts from seismic surveys have not demonstrated biologically significant adverse impacts on marine mammal populations.

    Industry continually monitors the effectiveness of the mitigation strategies it employs and funds research to better understand interactions between E&P operations and marine mammals.

    Not all marine life hears the same frequencies equally well. Much like the differences in hearing between humans and bats or dogs, some marine animals hear well at higher frequencies, and relatively poorly at lower frequencies. Others hear better at lower frequencies.

    Some studies have shown that marine mammal hearing sensitivity may be temporarily affected if exposed to sound at levels encountered very close to an operating seismic sound source. Other studies have found that marine mammals did not react to sounds that would only be realized within a few tens of meters of a typical seismic array.
    The E&P industry remains committed to improving the scientific understanding of the impacts of our operations on marine life.

    To provide the utmost safety precautions, seismic surveys in the U.S. Outer Continental Shelf are only conducted with measures in place to protect animals from high sound exposure levels.

    The best available scientific information also indicates that the level of sound required to injure dolphins may be higher than previously thought.

    Animal strandings – which opponents of oil and natural gas production incorrectly claim are due to seismic surveys – can occur for a number of reasons, e.g., sickness, disorientation, natural mortality, extreme weather conditions or injury. Natural occurrences of stranded marine mammals have been documented in records dating from the 7th century.

    Source: http://www.api.org/OCS and Seismic Surveying 101

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