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Soundings Archive

NMFS Explains Position on Several Marine Mammal Issues
The U.S. National Marine Fisheries Service has authorized the U.S. Geological Service to "take" specified numbers of marine mammals during a low-energy seismic survey in the Gulf of Mexico. NMFS issued this take authorization pursuant to the U.S. marine mammal aceThis take authority is issued pursuant to the U.S. Marine Mammal Protection Act. NMFS only authorizes behavioral effects takes.

In its Federal Register notice of the USGS take authorization, NMFS responds to comments on its proposed take authorizations. NMFS' responses clarify NMFS' position on several recurring issues under the MMPA. For example, with regard to new acoustic criteria for Level A physical effects under the MMPA, NMFS states

    "NMFS is currently developing new acoustic guidelines for assessing the effects of anthropogenic sound on marine mammal species under our jurisdiction. The updated acoustic criteria will be based on recent advances in science and includes studies that take into account frequency sensitivity associated with noise-induced hearing loss. Nevertheless, since these original criteria (i.e., 180/190 dB [rms]) were based on TTS, in the majority of situations, especially for intermittent sources, like airguns, the ranges of exclusion zones that account for these new data are equal, if not smaller than the zones based on the 180 and 190 dB (rms) thresholds. Thus, the exclusion zones to 180 and 190 dB are expected to be protective. More information regarding NMFS's marine mammal acoustic guidelines can be found online at: acoustics/guidelines.htm."
With regard to requiring mitigation measures that effect the least practicable adverse impact on the affected marine mammal species and stocks and their habitat, NMFS explains that it
    "has carefully evaluated the applicant's mitigation measures and has considered a range of other measures in the context of ensuring that NMFS prescribes the means of effecting the least practicable adverse impact on the affected marine mammal species and stocks and their habitat. NMFS's evaluation of potential measures included consideration of the following factors in relation to one another: (1) The manner in which, and the degree to which, the successful implementation of the measure is expected to minimize adverse impacts to marine mammals; (2) The proven or likely efficacy of the specific measure to minimize adverse impacts as planned; and (3) The practicability of the measure for applicant implementation."
With regard to making a negligible impact determination,
    "NMFS evaluated factors such as: (1) The number of anticipated injuries, serious injuries, or mortalities; (2) The number, nature, and intensity, and duration of Level B harassment...; (3) The context in which the takes occur (i.e., impacts to areas of significance, impacts to local populations, and cumulative impacts when taking into account successive/contemporaneous actions when added to baseline data); (4) The status of stock or species of marine mammals (i.e., depleted, not depleted, decreasing, increasing, stable, impact relative to the size of the population); (5) Impacts on habitat affecting rates of recruitment/survival; and (6) The effectiveness of monitoring and mitigation measures (i.e., the manner and degree in which the measure is likely to reduce adverse impacts to marine mammals, the likely effectiveness of the measures, and the practicability of implementation)."
  • Click here to read NMFS' Federal Register notice responding to comments
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