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Federal Register / Vol. 86, No. 86 / Thursday, May 6, 2021 / Rules and Regulations entangled North Atlantic right whale was observed floating over 60 miles 96.6 km offshore of Virginia Beach Costidis et al. 2019. All North Atlantic right whale strandings in Virginia waters have occurred on ocean-facing beaches along Virginia Beach and the barrier islands seaward of the lower Delmarva Peninsula Costidis et al.
2017. Due to the low occurrence of North Atlantic right whales in the project area, NMFS is not authorizing take of this species.
Fin whales have been sighted off Virginia Cetacean and Turtle Assessment Program CeTAP 1981, 1982; Swingle et al. 1993; DoN 2009;
Hyrenbach et al. 2012; Barco 2013;
Mallette et al. 2016a, b; Aschettino et al.
2018; Engelhaupt et al. 2017, 2018;
Cotter 2019, and in the Chesapeake Bay Bailey 1948; CeTAP 1981, 1982;
Morgan et al. 2002; Barco 2013;
Aschettino et al. 2018; however, they are not likely to occur in the project area. Sightings have been documented around the Chesapeake Bay Bridge Tunnel CBBT during the winter months CeTAP 1981, 1982; Barco 2013;
Aschettino et al. 2018.
Eleven fin whale strandings have occurred off Virginia from 1988 to 2016
mostly during the winter months of February and March, followed by a few in the spring and summer months Costidis et al. 2017. Six of the strandings occurred in the Chesapeake Bay three on eastern shore; three on western shore with the remaining five occurring on the Atlantic coast Costidis et al. 2017. Documented strandings near the project area have occurred:
February 2012, a dead fin whale washed ashore on Oceanview Beach in Norfolk Swingle et al. 2013; December 2017, a live fin whale stranded on a shoal in Newport News and died at the site Swingle et al. 2018; February 2014, a dead fin whale stranded on a sand bar
in Pocomoke Sound near Great Fox Island, Accomack Swingle et al. 2015;
and, March 2007, a dead fin whale near Craney Island, in the Elizabeth River, in Norfolk Barco 2013. Only stranded fin whales have been documented in the project area; no free-swimming fin whales have been observed. Due to the low occurrence of fin whales in the project area, NMFS is not authorizing take of this species.
Minke whales have been sighted off Virginia CeTAP 1981, 1982; Hyrenbach et al. 2012; Barco 2013; Mallette et al.
2016a, b; McLellan 2017; Engelhaupt et al. 2017, 2018; Cotter 2019, near the CBBT Aschettino et al. 2018, but sightings in the project area are from strandings Jensen and Silber 2004;
Barco 2013; DoN 2009. In August 1994, a ship strike incident involved a minke whale in Hampton Roads Jensen and Silber 2004; Barco 2013. It was reported that the animal was struck offshore and was carried inshore on the bow of a ship DoN 2009. Twelve strandings of minke whales have occurred in Virginia waters from 1988 to 2016 Costidis et al. 2017.
There have been six minke whale stranding from 2017 through 2020 in Virginia waters. Because all known minke whale occurrences in the project area are due to strandings, NMFS is not authorizing take of this species.
A detailed description of the species likely to be affected by the Navys project, including brief introductions to the species and relevant stocks as well as available information regarding population trends and threats, and information regarding local occurrence, were provided in the proposed rule 85
FR 83001; December 21, 2020; since that time, we are not aware of any changes in the status of these species and stocks, except that the Gulf of Maine humpback whale stock has been designated as strategic in the 2020 draft SARs; therefore, detailed descriptions
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are not provided here. Please refer to the proposed rule for these descriptions 85
FR 83001; December 21, 2020. Please also refer to NMFS website https
www.fisheries.noaa.gov/find-species for generalized species accounts.
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 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. Note that no direct measurements of hearing ability have been successfully completed for mysticetes i.e., LF 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 LF
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 2.

TABLE 2MARINE MAMMAL HEARING GROUPS
NMFS, 2018
Generalized hearing range

Hearing group
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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 160 kHz.
275 Hz to 160 kHz.
50 Hz to 86 kHz.
60 Hz to 39 kHz.

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
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that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids,
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especially in the higher frequency range Hemila et al. 2006; Kastelein et al.
2009; Reichmuth and Holt, 2013.

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