NMFS Defends Its Level B Behavioral Take Criteria

The United States National Marine Fisheries Service has issued an Incidental Harassment Authorization under the Marine Mammal Protection Act to Apache Alaska Corporation to take marine mammals, by harassment, incidental to a proposed 3D seismic survey in Cook Inlet, Alaska, between March 4, 2014, and December 31, 2014.  This IHA is effective March 4, 2014, through December 31, 2014. In its Federal Register notice of this IHA, NMFS responds to comments on the proposed IHA that criticize NMFS’ methods for determining MMPA Level Behavioral Takes.   In its response, NMFS states that

“NMFS uses 160 dB (rms) as the exposure level for estimating Level B harassment takes for most species in most cases. This threshold was established for underwater impulse sound sources based on measured avoidance responses observed in whales in the wild. Specifically, the 160 dB threshold was derived from data for mother-calf pairs of migrating gray whales (Malme et al., 1983, 1984) and bowhead whales (Richardson et al., 1985, 1986) responding to seismic airguns (e.g., impulsive sound source). We acknowledge there is more recent information bearing on behavioral reactions to seismic airguns, but those data only illustrate how complex and context-dependent the relationship is between the two. See 75 FR 49710, 49716 (August 13, 2010) (IHA for Shell seismic survey in Alaska; response to comment 9). Accordingly, it is not a matter of merely replacing the existing threshold with a new one. NOAA is developing relatively more sophisticated draft guidelines for determining acoustic impacts, including information for determining Level B harassment thresholds. Due to the complexity of the task, the draft guidelines will undergo a rigorous review that includes internal agency review, public notice and comment, and external peer review before any final product is published. In the meantime, and taking into consideration the facts and available science, NMFS determined it is reasonable to use the 160 dB threshold for estimating takes of marine mammals in Cook Inlet by Level B harassment. However, we discuss the science on this issue qualitatively in our analysis of potential effects to marine mammals.”

Click here to read NMFS’ Federal Register notice for this IHA.







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