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Federal Register / Vol. 86, No. 23 / Friday, February 5, 2021 / Notices
Modeling indicates there is limited potential for auditory injury to humpback whales during pile driving even in the absence of the proposed mitigation measures; the remaining fifteen species are predicted to experience no Level A harassment, based on modeling results that assumed 10 dB attenuation Table 16.
NMFS expects that any exposures above the Level A harassment threshold would be in the form of slight PTS, i.e.
minor degradation of hearing capabilities within regions of hearing that align most completely with the energy produced by pile driving i.e. the low-frequency region below 2 kHz, not severe hearing impairment. If hearing impairment occurs, it is most likely that the affected animal would lose a few decibels in its hearing sensitivity, which in most cases is not likely to meaningfully affect its ability to forage and communicate with conspecifics, much less impact reproduction or survival.
Additionally, the number of Level A
harassment takes proposed for authorization are relatively low for all marine mammal stocks and species: For three of the stocks, only one take by Level A harassment is proposed for authorization i.e., fin whale, sei whale, and minke whale, and for most of the remaining stocks, NMFS does not propose to authorize any takes by Level A harassment over the duration of the project; for the remaining stock i.e., humpback whale, NMFS proposes to authorize four takes by Level A
harassment. As described above, any PTS incurred would be no more than a few decibels of lost hearing sensitivity that would not impact annual rates of recruitment or survival for any individual.
Repeated exposures of individuals to relatively low levels of sound outside of preferred habitat areas are unlikely to significantly disrupt critical behaviors.
Thus, even repeated Level B harassment of some small subset of an overall stock is unlikely to result in any significant realized decrease in viability for the affected individuals, and thus would not result in any adverse impact to the stock as a whole. Level B harassment will be reduced to the level of least practicable adverse impact through use of proposed mitigation measures and, if sound produced by project activities is sufficiently disturbing, marine mammals are likely to simply avoid the area while the activity is occurring.
Therefore, NMFS expects that animals disturbed by project sound would likely move away from the sound source during project activities in favor of other, similar habitats. NMFS expects
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that any avoidance of the project area by marine mammals would be temporary in nature and that any marine mammals that avoid the project area during construction would not be permanently displaced.
Feeding behavior is not likely to be significantly impacted, as prey species are mobile and are broadly distributed throughout the project area; therefore, marine mammals that may be temporarily displaced during construction activities are expected to be able to resume foraging once they have moved away from areas with disturbing levels of underwater noise.
Because of the temporary nature of the disturbance and the availability of similar habitat and resources in the surrounding area, the impacts to marine mammals and the food sources that they utilize are not expected to cause significant or long-term consequences for individual marine mammals or their populations. There are no areas of notable biological significance for marine mammal feeding known to exist in the project area. In addition, there are no rookeries or mating or calving areas known to be biologically important to marine mammals within the proposed project area.
NMFS concludes that exposures to marine mammals due to the proposed project would result in only short-term effects to individuals exposed. Marine mammals may temporarily avoid the immediate area but are not expected to permanently abandon the area. Impacts to breeding, feeding, sheltering, resting, or migration are not expected, nor are shifts in habitat use, distribution, or foraging success. NMFS does not anticipate the marine mammal takes that would result from the proposed project would impact annual rates of recruitment or survival.
As described above, humpback whales, minke whales, and gray and harbor seals are experiencing ongoing UMEs. For minke whales, although the ongoing UME is under investigation as occurs for all UMEs, this event does not provide cause for concern regarding population level impacts, as the likely population abundance is greater than 20,000 whales. With regard to humpback whales, the UME does not yet provide cause for concern regarding population-level impacts. Despite the UME, the relevant population of humpback whales the West Indies breeding population, or DPS remains healthy. The West Indies DPS, which consists of the whales whose breeding range includes the Atlantic margin of the Antilles from Cuba to northern Venezuela, and whose feeding range primarily includes the Gulf of Maine,
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eastern Canada, and western Greenland, was delisted. The status review identified harmful algal blooms, vessel collisions, and fishing gear entanglements as relevant threats for this DPS, but noted that all other threats are considered likely to have no or minor impact on population size or the growth rate of this DPS Bettridge et al., 2015. As described in Bettridge et al.
2015, the West Indies DPS has a substantial population size i.e., approximately 10,000; Stevick et al., 2003; Smith et al., 1999; Bettridge et al., 2015, and appears to be experiencing consistent growth. With regard to gray seals and harbor seals, although the ongoing UME is under investigation, the UME does not yet provide cause for concern regarding population-level impacts to any of these stocks. For harbor seals, the population abundance is over 75,000 and annual M/SI 345 is well below PBR 2,006 Hayes et al., 2020. For gray seals, the population abundance is over 500,000, and abundance is likely increasing in the U.S. Atlantic EEZ and in Canada Hayes et al., 2020. Proposed authorized takes by Level A harassment of humpback whales are low i.e., no more than four takes by Level A harassment proposed for authorization and, as described above, any Level A harassment would be expected to be in the form of slight PTS, i.e. minor degradation of hearing capabilities which is not likely to meaningfully affect the ability to forage or communicate with conspecifics. No serious injury or mortality is expected or proposed for authorization, and Level B harassment of humpback whales and minke whales and gray and harbor seals will be reduced to the level of least practicable adverse impact through use of proposed mitigation measures. As such, the proposed authorized takes of these species would not exacerbate or compound the effects of the ongoing UMEs on the populations.
In summary and as described above, the following factors primarily support NMFS preliminary determination that the impacts resulting from this activity are not expected to adversely affect the species or stock through effects on annual rates of recruitment or survival:
No mortality or serious injury is anticipated or proposed for authorization;
No Level A harassment of North Atlantic right whales would occur and Level B harassment will be minimized via extended mitigation measures;
The anticipated impacts of the proposed activity on marine mammals would be temporary behavioral changes primarily avoidance of the project area and limited instances of Level A

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