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Federal Register / Vol. 86, No. 33 / Monday, February 22, 2021 / Notices TABLE 12MARINE MAMMAL DENSITIES IN THE GEOGRAPHIC REGION BY SEASON
Winter NovMar
Species Bowhead Whale
Gray Whale
Beluga Whaleb
Ringed Seal
Spotted Seal
Bearded Seal

Spring AprJun a
0 0
0 0.507
0 0.003

Summer JulAug
0 0
0 0.548
0 0.003

0.005
0.00003
0.009
0.274
0.055
0.047

Fall SeptOct 0.017
0.00003
0.001
0.274
0 0.047

a AGDCs pile driving contingency period extends from late February to April 2024, however, very little if any pile driving is likely to occur in April.
b As noted above, the beluga whale densities were updated to include 2019 ASAMM survey data. Clarke et al., 2020.

Take Calculation and Estimation In this section, we describe how the information provided above is brought together to produce a quantitative take estimate.
To estimate Level A and Level B
harassment takes, AGDC first multiplied the area km2 estimated to be ensonified above the Level A or Level B
harassment thresholds for each species, respectively, for pile driving and removal of each pile size and hammer type by the duration days of that activity in that season by the seasonal density for each species number of animals/km2. NMFS generally concurs with, and has adopted this method, with the exception of the estimated duration of the activity, as described below.
AGDC expects that construction will likely be completed during the openwater construction season. AGDC
calculated that the construction will require approximately 164 days of inwater work; however, this estimate does not take into account that different pile types would be installed on the same day, therefore reducing the total number of pile driving days. Therefore, NMFS
expects that the take calculation using AGDCs method described above overestimates take. Taking into consideration the number of calendar days, construction occurring 6 days per week, and no work occurring on days during the whaling season, there are 123
days in the months of July through October on which the work is expected to occur 75 percent of the 164 days used to inform the take estimate in AGDCs application. As such, NMFS is authorizing 75 percent of the take estimate calculated by AGDC for each species except for Level A harassment
take of bowhead whales and beluga whales, and Level B harassment of gray whales as noted below.
NMFS recognizes that AGDC may work for a short time outside of this period in their February to April contingency period; however, we expect that if AGDC works during the contingency period, it would be because of construction delays and therefore, days on which they did not work during their planned open water work season. Additionally, we recognize that ringed seals may be present in ice lairs during the contingency period.
However, AGDC must initiate pile driving prior to March 1, as described in the Mitigation Measures section.
Initiating pile driving before March 1 is expected to discourage seals from establishing birthing lairs near pile driving. As such, we expect that this measure will eliminate the potential for physical injury to ringed seals during this period. Therefore, NMFS expects that the take estimate described herein is reasonable even if AGDC must pile drive during their contingency period.
NMFS calculated take using summer densities for all species except for bowhead whale. For bowhead whales, NMFS conservatively calculated take using the fall density.
For bowhead whale, including the 2019 ASAMM surveys decreases the fall bowhead density to 0.016 bowhead whales/km2. However, NMFS has conservatively used the higher density included in the proposed IHA to calculate Level B harassment take of bowhead whale. Using the lower density results in an estimate of 103
Level B harassment takes of bowhead, which NMFS considers to be a
negligible difference, though less conservative.
For gray whale, including the 2019
ASAMM survey data decreases the summer density to 0.000028 gray whales/km2. Using this lower density results in a calculated take estimate of 0.18 takes by Level B harassment of gray whale, but in consideration of group size, the take estimate remains 2 takes by Level B harassment, as included in the proposed IHA.
For beluga whale, including the 2019
ASAMM survey data increases the summer density to 0.0009 beluga whales/km2, which significantly increases the estimated Level A and Level B harassment takes. Therefore, NMFS recalculated the Level A and Level B harassment take estimates using this new density. The updated estimates are included in Table 14 and Table 15.
As noted in Table 15, in the proposed IHA 85 FR 43382; July 16, 2020, Level A harassment takes for beluga whale and phocids were erroneously calculated using the LF cetacean Level A harassment zone sizes. The calculations in Table 15 and in the final IHA reflect the corrected estimated Level A harassment take for phocids and beluga whale, calculated using the correct Level A harassment zone sizes.
The Final IHA does not authorize Level A harassment take of beluga whale nor was it included in the proposed IHA
despite the change to the calculation, given the small size of the Level A
harassment zones, the low likelihood that a beluga will occur in this area, the lack of modeled Level A harassment takes, and the required mitigation, as described below.

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TABLE 13AREA OF LEVEL A AND LEVEL B HARASSMENT ZONES
Area of level A harassment zone km2
LF cetaceans 11.5-in H-pile impact
14-in H-pile impact

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MF cetaceans
4.48
3.15

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0.01
0.00

22FEN2

Phocids 1.28
0.90

Area of level B
harassment zone km2
0.37
1.25