Quiero saber acerca de...

14729

Federal Register / Vol. 86, No. 51 / Thursday, March 18, 2021 / Notices kilometers km2 21.5 square miles in Sitka Sound. As of February 21, 2021
the project has recorded small Level B
harassment takes of three species. This IHA proposes to authorize the remaining take associated with the work not completed under the 2020 IHA. The original proposed and final IHA
documents, monitoring report, and public comments can be found on our project web page at: https
www.fisheries.noaa.gov/action/
incidental-take-authorization-old-sitkadock-north-dolphins-expansion-projectsitka-alaska.
Detailed Description of the Activity A detailed description of the demolition and construction activities for which take is proposed here may be found in the notices of the proposed and final IHAs for the 2020 IHA. The location, and nature of the activities, including the types of equipment planned for use, are identical to those described in the previous notices.
The 2020 IHA was only valid from October 1 through February 28 because HPMS believed their Army Corps of Engineers permit would prohibit work from March 1 and June 15, and that cruise ship activity would prevent work from May 1 to October 1. Thus the Endangered Species Act Biological Opinion also prohibited work from March 1 to October 1. As it turned out, the Army Corps of Engineers permit did not prohibit work between March 1 and June 15 and large cruise ship activity did not take place in 2020, nor is it expected to occur in the summer of 2021. This new IHA will be effective year-round, and the applicant hopes to begin work close to April 15. In this part of Alaska, herring are common during spring and summer as discussed in the proposed 2020 IHA. Stellers sea lions in particular are more common in the project area during this time because they feed on herring. Because of this, the applicant has requested a larger daily rate of Level B harassment take of Stellers sea lions as discussed below.
The 2020 IHA considered an impulsive source level for the effects of
down-the-hole drilling that was in line with our previous understanding of that activity. Since the 2020 IHA was analyzed, our understanding of downthe-hole drilling has evolved based on recent hydroacoustic monitoring. Our recommended impulsive source level for calculating Level A harassment isopleths has changed for holes of the size HPMS is creating. Below we update our analysis and the Level A harassment isopleths using our current understanding of down-the-hole drilling.
Description of Marine Mammals A description of the marine mammals in the area of the activities for which authorization of take is proposed here, including information on abundance, status, distribution, and hearing, may be found in the notices of the proposed and final IHAs for the 2020 authorization.
NMFS has reviewed the monitoring data from the 2020 IHA, recent draft Stock Assessment Reports, information on relevant Unusual Mortality Events, and other scientific literature, and determined that neither this nor any other new information affects which species or stocks have the potential to be affected or the pertinent information in the Description of the Marine Mammals in the Area of Specified Activities contained in the supporting documents for the 2020 IHA.
Potential Effects on Marine Mammals and Their Habitat A description of the potential effects of the specified activity on marine mammals and their habitat for the activities for which take is proposed here may be found in the notices of the proposed and final IHAs for the 2020
authorization. NMFS has reviewed the monitoring data from the 2020 IHA, recent draft Stock Assessment Reports, information on relevant Unusual Mortality Events, and other scientific literature, and determined that, besides the revised understanding of down-thehole drilling source levels and Stellers sea lion occurrence mentioned above and analyzed below, neither this nor
any other new information affects our initial analysis of impacts on marine mammals and their habitat.
Estimated Take A detailed description of the methods and inputs used to estimate take for the specified activity are found in the Notice of the Final IHA for the 2020
IHA. Specifically, the source levels, and days of operation applicable to this authorization remain unchanged from the previously issued IHA, except for the change to the down-the-hole drilling source level and Level A harassment zones described below and in Table 1.
Similarly, the stocks taken, methods of take, and types of take remain unchanged from the previously issued IHA. The only change to the marine mammal density/occurrence data is an increase in Stellers sea lions around the time of the herring run as discussed below. The only change to the number of proposed takes, which are indicated below in Table 2, is to account for the increased occurrence of Stellers sea lions and the work remaining to be completed.
Because the Level B source levels and harassment zone sizes for down-thehole drilling did not change from the 2020 IHA we do not propose changes to the overall or Level B harassment take from down-the-hole drilling. However, in the 2020 IHA we used a source level of 166.2 dB RMS decibels root mean square to calculate the Level A
harassment isopleths for down-the-hole drilling. More recent hydroacoustic data and analysis from down-the-hole drilling projects has led us to recommend the use of a source level of 164 dB SELss sound exposure level single strike from Denes et al. 2019 for the impulsive component of this source relevant for Level A harassment isopleth calculation. Using this source level and the equivalent user spreadsheet inputs, the Level A harassment isopleths for the down-the-hole drilling increase from 10
to 336.5 m, depending on hearing group, in the 2020 IHA, to 26.1 to 873.7 m in this proposed IHA Table 1.

TABLE 1CALCULATED DISTANCES TO LEVEL A HARASSMENT ISOPLETHS FOR DOWN-THE-HOLE DRILLING FROM THE
2020 IHA AND THIS PROPOSED IHA
Level A harassment zone m jbell on DSKJLSW7X2PROD with NOTICES

Activity
Lowfrequency cetaceans
33-inch down-the-hole 2020 IHA
33-inch down-the-hole this IHA

VerDate Sep<11>2014

16:49 Mar 17, 2021

Jkt 253001

PO 00000

Frm 00010

Fmt 4703

282.5
733.5

Sfmt 4703

Midfrequency cetaceans
Highfrequency cetaceans
10.0
26.1

E:FRFM18MRN1.SGM

336.5
873.7

18MRN1

Phocid pinnipeds 151.2
392.5

Otariid pinnipeds 11.0
28.6