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Federal Register / Vol. 86, No. 33 / Monday, February 22, 2021 / Notices
TABLE 1ACOUSTIC DATA FROM UNATTENUATED IMPACT INSTALLATION OF 48 STEEL PIPE PILESContinued
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Processed data of datasets used to calculate the median:

Source dist. m
Measured SPLpk dB re 1
Pa
Measured SPLrms dB re 1
Pa
Measured SEL
dB re 1
Pa2s
Normalized to 10-m SL
SPLpk dB re 1 Pa @10 m
Normalized to 10m SL
SPLrms dB re 1 Pa @10 m
Normalized to 10m SL
SEL
dB re 1
Pa2s @10
m
Location
TT13.5R Mid 9

10

205

186

174

205

186

174

Naval Base Kitsap.

IP5

11

212.5

197.9

186.7

213.3278537

198.7278537

187.5278537

IP6 off

12

208.7

193.2

184.5

210.2836249

194.7836249

186.0836249

IP1

14

213.2

199

185.1

216.1225607

201.9225607

188.0225607

Port of Anchorage.
Port of Anchorage.
Port of Anchorage.

Median

207.3

193.4

181.3

Therefore, given that source levels at the project site are likely lower given the water depth, and considering that the 60-in CISS pile attenuated proxy source level is higher than the median source level of other source levels for impact installation of 48-in piles, NMFS
has continued to use the initially proposed source levels to calculate the Level A and Level B harassment zones for the final authorization. NMFS
intends to update the Level A and Level B harassment zone sizes with the verified zone sizes, and potentially the associated shutdown zones, as appropriate. It is likely that the SSV will reflect smaller zone sizes, which would therefore be easier for protected species observers PSOs to observe a larger portion of the zones.
Comment 37: The Commission recommended that NMFS 1 increase the a Level A harassment zones from 1,575 m to 2,249 m for LF cetaceans, from 56 m to 80 m for MF cetaceans, and from 843 m to 1,204 m for phocids, b shutdown zones from 1,600 m to at least 2,250 m for LF cetaceans and from 50 m to at least 80 m for MF cetaceans, and c Level B harassment zone from 2,154 m to 3,754 m during impact installation of 48-in piles; 2 revise the numbers of Level A and B harassment takes during impact installation of 48-in piles; 3 include Level A harassment takes of bowhead whales during impact installation of 48-in piles or prohibit AGDC from conducting such activities at night or in low-visibility conditions;
and 4 ensure the Level A harassment takes were estimated correctly for MF
cetaceans and phocids during all proposed activities.
Response: As stated in NMFS
response to Comment 36, NMFS did not adopt the commenters recommended source level change for impact installation of 48-in piles. Therefore, it is not appropriate to adopt the
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recommended changes to the Level A
and Level B harassment zones and shutdown zones that were based upon those recommended source level changes, nor is it appropriate to revise the number of Level A and Level B
harassment takes that are estimated to occur during impact installation of 48in piles, as those recommendations are based upon a change to the Level A and Level B harassment zone sizes.
Take by Level A harassment of bowhead whale during any activity, including impact installation of 48-in piles, is still not expected to occur given the water depth in the Level A
harassment zone. Further, there have been no bowhead whales observed in Block 1a which encompasses the area between the shoreline and the barrier islands, including Prudhoe Bay during ASAMM surveys since they began in 2016, further supporting NMFS
conclusion bowhead whales are not expected to occur within the Level A
harassment zone during construction.
Additionally, in the rare event that a bowhead whale were to enter the Level A harassment zone, it is likely that PSOs would detect the animal and that a shutdown would be implemented, preventing a take by Level A
harassment. Therefore, Level A
harassment take of bowhead whale is not included in this authorization. The final authorization does not prohibit AGDC from conducting construction activities at night or in low-visibility conditions, but notes that AGDC will use NVD and IR during those conditions. Additionally, given that most construction is expected to occur during the open water period when daylight is continuous July and August, or the majority of the time >70
percent of the time in September, the majority of construction will occur during daylight hours, even with work occurring 24-hours per day. Although,
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Report
Naval Base Kitsap at Bangor Trident Support Facilities EHW2 2013; p.
94, 101, 107.
Austin et al. 2016;
p. 7073.
Austin et al. 2016;
p. 7073.
Austin et al. 2016;
p. 7073.

NMFS recognizes that other conditions, such as fog, could limit visibility.
NMFS updated the Level A
harassment take calculations for phocids and beluga whale by correcting the zone sizes used in the calculation.
The updated calculation did not result in a change to the authorized Level A
harassment take of beluga whale, but the authorized Level A harassment take of ringed seal, spotted seal, and bearded seal decreased. Please see the Estimated Take section for additional information on changes to the take estimate.
Comment 38: The Commission recommended that NMFS 1 have its experts in underwater acoustics and bioacoustics review and finalize as soon as possible, its recommended proxy source levels for impact pile driving of the various pile types and sizes, 2
compile and analyze the source level data for vibratory pile driving of the various pile types and sizes in the near term, and 3 ensure action proponents use consistent and appropriate proxy source levels in all future rulemakings and proposed IHAs. If a subset of source level data is currently available i.e., vibratory pile driving of 24-in steel piles, those data should be reviewed immediately and usedthe data should not be retained until the other vibratory source levels are finalized.
Response: NMFS concurs with the Commissions recommendation and has prioritized these efforts.
Comment 39: A commenter stated that NMFS finding that there would be no impacts on subsistence harvest is arbitrary.
Response: NMFS did not find that there would be no impacts to subsistence harvests. Rather, NMFS
found that, based on the description of the specified activity, the mitigation measures described to minimize adverse effects on the availability of marine mammals for subsistence purposes, and
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