Voglio sapere a riguardo di…

8522

Federal Register / Vol. 86, No. 23 / Friday, February 5, 2021 / Notices
within the small time period of vibratory pile driving significantly reduces the risk of behavioral harassment exposures. In addition, marine mammal species in this region are not expected to remain in proximity to the cofferdam location for an extended amount of time. Although the modeled Level B harassment exposure estimates for harbor and gray seals were large 1,305, seals are only expected to be seasonally present in the region, and there are no known rookeries documented near the cofferdam location. Seals typically haul-out for some portion of their daily activities, often in large groups Hayes et al., 2020; however, the in-water median group size is estimated to be 13

animals depending on the distance to shore Herr et al., 2009 with larger groups typically being associated with direct proximity to a haul-out site.
There are a few documented haul-out sites around Long Island, New York; the nearest site is in Montauk Point, approximately 20 km northeast of the cofferdam location, where seals are primarily observed in winter CRESLI, 2019. Long Island, NY represents the northernmost portion of the range for the Western North Atlantic Migratory Coast Stock of bottlenose dolphins.
Bottlenose dolphin occurrence is also seasonal along the coast of Long Island, peaking in late summer/early fall Hayes et al., 2020. Potential exposures of bottlenose dolphins varied substantially
across the proposed construction months, with a minimum number of potential Level B harassment exposures in March 65 and a maximum in October 2007. The impact of vibratory pile driving on this species and both seal species will be largely dependent on the timing of the installation and extraction of the cofferdam.
Given the possibility that vibratory pile driving could occur anytime between October and May, the maximum modeled exposure for each species across months was used to conservatively predict take numbers and assess impacts resulting from vibratory pile driving Table 20.

TABLE 20PROPOSED LEVEL B HARASSMENT TAKE RESULTING FROM VIBRATORY PILE DRIVING
Population estimate
Species/stock Fin whale
Minke whale
Sei whale
Humpback whale
North Atlantic right whale
Atlantic white sided dolphin
Common dolphin
Bottlenose dolphin
Harbor porpoise
Gray seal
Harbor seal

HRG Surveys Potential exposures of marine mammals to acoustic impacts from HRG
survey activities were estimated using an approach similar to that described for installation and removal of a cofferdam.
For HRG surveys, however, the ZOI was calculated as follows:
ZOI = 2rd + pr2
where r is the linear acoustic range from the source to the largest estimated Level A
harassment 36.5 m and Level B
harassment 141 m isopleths, and d is the survey trackline distance per day 70
km.

jbell on DSKJLSW7X2PROD with NOTICES2

The daily area was then multiplied by the mean annual density of a given marine mammal species. Finally, the resulting value was multiplied by the number of proposed survey days 60.
Modeled distances to isopleths corresponding to the Level A
harassment threshold are very small
VerDate Sep<11>2014

19:54 Feb 04, 2021

Jkt 253001

<1 m for three of the four marine mammal functional hearing groups that may be impacted by the proposed activities i.e., low frequency and mid frequency cetaceans, and phocid pinnipeds; see Table 12. Based on the extremely small Level A harassment zones for these functional hearing groups, the potential for species within these functional hearing groups to be taken by Level A harassment is considered so low as to be discountable.
These three functional hearing groups encompass all but one of the marine mammal species listed in Table 3 that may be impacted by the proposed activities. There is one species harbor porpoise within the high frequency functional hearing group that may be impacted by the proposed activities.
However, the largest modeled distance to the Level A harassment threshold for the high frequency functional hearing group was only 36.5 m Table 12. More
PO 00000

Frm 00034

Fmt 4701

Sfmt 4703

6,802
21,968
6,292
1,393
412
93,233
172,974
62,851
95,543
505,000
75,834

Proposed level B takes 2
3 0
1 6
1 4
2,007
11
1,305
1,305

importantly, Level A harassment would also be more likely to occur at close approach to the sound source or as a result of longer duration exposure to the sound source, and the narrow beam width and directional nature of the sources, as well as the mitigation measures including a 100 m exclusion zone for harbor porpoises, minimize the potential for exposure to HRG
sources that would result in Level A
harassment. In addition, harbor porpoises are a notoriously shy species which is known to avoid vessels and would also be expected to avoid a sound source prior to that source reaching a level that would result in injury Level A harassment. Therefore, NMFS has determined that the potential for take by Level A harassment of harbor porpoises is so low as to be discountable. The modeled Level B harassment exposures of marine mammals resulting from HRG
survey activities are shown in Table 21.

E:FRFM05FEN2.SGM

05FEN2