2024-27442. Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Skagway Ore Terminal Redevelopment Project

Table 1—Level A and Level B Harassment Isopleths ( m ) for Impact and Vibratory Pile Driving

Activity	Level A harassment zone (m) 1					Level B harassment zone (m)
	LF	HF	VHF	Phocids	Otariids
24-in steel pile, Impact Installation	1,970.4	251.4	3,049.2	1,750.4	652.5	857.7
24-in steel pile,* Vibratory Installation and Removal	5.6	2.2	4.6	7.2	2.4	3,981
14-in timber pile, Vibratory Removal	3.7	1.4	3	4.7	1.6	3,415
1  Zones are based on the 2024 Updated Technical Guidance, further described above. This is new information that was not available at the time of the initial and modified IHA. Species groups have also been re-named in the Updated Technical Guidance.
* Based on the up to 30-in piles included in the initial IHA that also included pile sizes: 10.75-in, 14-in, 16-in, 20-in, 24-in, 28-in, and 30-in.

Table 2—Amount of Taking, by Level A and Level B Harassment, by Species and Stock and Percent of Take by Stock

Species	Stock	Initial IHA authorized Level A take	Initial IHA authorized Level B take	Renewal Level A take	Renewal Level B take	Percent of stock
Humpback Whale	Hawaii	2	13	0	* 2	<1
	Mexico—North Pacific	0	1	0	0	0
Minke Whale	Alaska	2	6	0	* 1	<1
Killer Whale 1	Eastern North Pacific, Northern Residents, Southeast Alaska + Eastern North Pacific, Alaska Residents + West Coast Transients + Gulf, Aleutian, Bering Sea Transients	2	90	0	* 25	<1
Dall's Porpoise	Alaska	43	193	0	4	<1
Harbor Porpoise	Northern Southeast Alaska Inland Waters	17	75	0	* 2	<1
Harbor Seal	Alaska—Lynn Canal/Stephens Passage	193	2,760	11	54	<1
Steller Sea Lion	Eastern U.S. + Western U.S	2	270	0	10	<1
Northern Fur Seal	Pribilof Islands/Eastern Pacific stock	2	45	0	3	<1
* Rounded up to assumed average group size based on Dahlheim et al., 2009.
1  Dahlheim et al. (2009) observed mean group sizes of 25 (resident ecotype) and 5 (transient ecotype) for killer whales in Southeast Alaska. While MOS observed only two killer whales during the initial IHA, it is possible that a larger group could enter the area during the renewal activities.

Description of Mitigation, Monitoring and Reporting Measures

The mitigation, monitoring, and reporting measures included as requirements in this authorization are substantially similar to those included in the FR notice announcing the issuance of the initial IHA, and the discussion of the least practicable adverse impact included in that document remains accurate (88 FR 60652, September 5, 2023). The only ( print page 92648) changes from the initial IHA are to the required shutdown zones and the removal of the acoustic monitoring requirement. The required shutdown zones (table 3) changed due to the changes in Level A harassment zone distances (table 1). As the initial IHA required shutdown zones equal to the Level A harassment zones, we retain that approach to mitigation in reflection of the new zones updated on the basis of the best scientific information available. Additionally, acoustic monitoring (as was required through the initial IHA) is not planned here, due to the minimal pile driving planned under this renewal IHA.

Table 3—Shutdown and Monitoring Zones

Activity	Minimum shutdown zone (m)					Harassment zone (m)
	LF cetacean	HF cetacean	VHF cetacean	Phocids	Otariids
24-in steel pile, Impact Installation	1,975	255	3,050	1,755	655	860
24-in steel pile, Vibratory Installation and Removal	10	10	10	10	10	3,985
14-in timber pile, Vibratory Removal	10	10	10	10	10	3,415