Quiero saber acerca de...

Federal Register / Vol. 86, No. 157 / Wednesday, August 18, 2021 / Notices Weddell Seal Weddell seals are large pinnipeds weighing up to 600 kg with typical weights between 300 and 500 kg.
Weddell seals aggregate on the ice to molt, and also sporadically dive during this period. After molting in fall-winter these seals disperse to sea; some individuals remain within the vicinity of their colonies, whereas other individuals disperse several hundreds of kilometers away and may not return to their colonies for several weeks.
The Weddell seals range includes coastal areas around the Antarctic continent and they are found in areas of both fast and pack ice. Weddell seals rarely venture into open, ice-free waters.
Animals inhabiting the islands of the mostly ice-free northern Antarctic Peninsula are primarily coastal in their distribution.
Weddell seals consume epipelagic 0
200 m, mesopelagic 2001000 m and benthic prey. They can dive to depths over 600 m to reach the deeper prey items. Their diet consists mainly of fish but they also eat cephalopods, decapods and Antarctic krill. Their feeding/haul out pattern is diurnal; they haulout during the day and forage at night in response to the vertical migration of their prey Andrews-Goff et al., 2010; as cited in Wursig et al., 2018.

Over three seasons two Antarctic summers and one winter of observation from January 21, 2019 through March 31, 2020, individual Weddell seals were observed on shore at Bonaparte Point from the end of February of 2019
through April of 2019. Weddell seals were observed swimming in Hero Inlet in early April 2019 on several occasions.
No Weddell seals were sighted again until mid-September of 2019, when an individual was again observed on the ice in Hero Inlet. After September 16, 2019, no Weddell seals were observed in the vicinity of Palmer Station until January 6, 2020; at that time a seal was observed in the vicinity of the outfall.
As with 2019 observations, Weddell seal sightings at Bonaparte Pointe increased in midto late February of 2020, and continued every day or every few days through March 27, 2020.
As indicated above, all 17 species in Table 4 temporally and spatially cooccur with the activity to the degree that take is reasonably likely to occur, and we have proposed authorizing it.
Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately
46207

assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008.
To reflect this, Southall et al. 2007
recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. No direct measurements of hearing ability have been successfully completed for mysticetes i.e., lowfrequency cetaceans. Subsequently, NMFS 2018 described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel dB threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al., 2007
retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 5.

TABLE 5MARINE MAMMAL HEARING GROUPS NMFS, 2018
Generalized hearing range

Hearing group Low-frequency LF cetaceans baleen whales
Mid-frequency MF cetaceans dolphins, toothed whales, beaked whales, bottlenose whales
High-frequency HF cetaceans true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L.
australis.
Phocid pinnipeds PW underwater true seals
Otariid pinnipeds OW underwater sea lions and fur seals

7 Hz to 35 kHz.
150 Hz to 16 kHz.
275 Hz to 160 kHz.
50 Hz to 86 kHz.
60 Hz to 39 kHz.

jbell on DSKJLSW7X2PROD with NOTICES

Represents the generalized hearing range for the entire group as a composite i.e., all species within the group, where individual species hearing ranges are typically not as broad. Generalized hearing range chosen based on 65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans Southall et al., 2007 and PW pinniped approximation.

The pinniped functional hearing group was modified from Southall et al.
2007 on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range Hemila et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 2013.
For more detail concerning these groups and associated frequency ranges, please see NMFS 2018 for a review of available information. Of the seventeen marine mammal species that may be present, six are classified as lowfrequency cetaceans i.e., all mysticete species, five are classified as midfrequency cetaceans i.e., all delphinid
VerDate Sep<11>2014

17:34 Aug 17, 2021

Jkt 253001

and ziphiid species and the sperm whale, one is classified as a highfrequency cetacean species i.e., hourglass dolphin. and there is one species of otariid and 4 phocids.
Potential Effects of Specified Activities on Marine Mammals and Their Habitat This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the
PO 00000

Frm 00034

Fmt 4703

Sfmt 4703

content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.
Acoustic effects on marine mammals during the specified activity can occur from the underwater noise resulting from DTH pile installation, vibratory hammer removal, limited impact driving to seat piles, rock chipping, and the use of a hydrogrinder. The effects of underwater noise from NSFs proposed activities have the potential to result in
E:FRFM18AUN1.SGM

18AUN1