A Notice by the National Oceanic and Atmospheric Administration on 09/09/2020. Response—As noted by the Commission, these comments reflect a longstanding disagreement between NMFS and the Commission regarding L-DEO's approach to modeling the output of their airgun array and its propagation through the water column. PSO resumes shall be provided to NMFS for approval. These are instances are characterized by "a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response," as outlined in the Marine Mammal Protection Act. While every effort has been made to ensure that and services, go to 09/23/2020, 42 All Rights Reserved.

R/V Langseth will likely leave out of and return to port in Dutch Harbor, Alaska, during September-October 2020. Response—NMFS does not expect that the proposed activities have the potential to result in injury or mortality to marine mammals and therefore does not agree that a blanket requirement for project activities to cease would be warranted. For seven of these species, taking by Level A and Level B harassment is authorized, with only Level B harassment authorized for the remaining 17 species. Using the HKY+I+G substitution model, we estimated the Maximum Likelihood cytb phylogeny with IQ-TREE (14); perturbation strength = 0.5, and the number of unsuccessful iterations = 100. The pinniped functional hearing group was modified from Southall et al. Visual PSOs shall use best professional judgment in making the decision to call for a shutdown if there is uncertainty regarding identification (i.e., whether the observed marine mammal(s) belongs to one of the delphinid genera for which shutdown is waived or one of the species with a larger exclusion zone). Shutdown procedures for live stranding or milling marine mammals include the following: If at any time, the marine mammal the marine mammal(s) die or are euthanized, or if herding/intervention efforts are stopped, the Director of OPR, NMFS (or designee) will advise the IHA-holder that the shutdown around the animals' location is no longer needed. PAM would take place in addition to the visual monitoring program. Visual monitoring typically is not effective during periods of poor visibility or at night, and even with good visibility, is unable to detect marine mammals when they are below the surface or beyond visual range. PSOs shall record detailed information about any implementation of mitigation requirements, including the distance of animals to the acoustic source and description of specific actions that ensued, the behavior of the animal(s), any observed changes in behavior before and after implementation of mitigation, and if shutdown was implemented, the length of time before any subsequent ramp-up of the acoustic source. Status of all sound source use in the 48 hours preceding the estimated time of stranding and within 50 km of the discovery/notification of the stranding by NMFS; and, If available, description of the behavior of any marine mammal(s) observed preceding (. Below, we describe the factors considered here in more detail and present the take numbers. The highest densities of feeding fin whales in the Bering Sea likely occur from June through September. Learn more here. Survey activity may continue for 30 minutes when the PAM system malfunctions or is damaged, while the PAM operator diagnoses the issue. However, there are no NSF-proposed seismic surveys on the R/V Langseth for this region in the foreseeable future. In addition, the Commission recommends that NMFS (1) explain why sound channels with downward refraction, as well as seafloor Start Printed Page 55648reflections, are not likely to occur during the geophysical survey, (2) specify the degree to which both of those parameters would affect the estimation (or underestimation) of Level B harassment zones in deep- and intermediate-water depths, (3) explain why L-DEO's model and other modeling approaches provide more accurate, realistic, and appropriate Level A and B harassment zones than BELLHOP (a different propagation model favored by the Commission), particularly for deep- and intermediate-water depths, and (4) explain why, if L-DEO's model and other modeling approaches are considered best available science, other action proponents that conduct seismic surveys are not implementing similar methods, particularly given their simplicity. Estimated exposures and authorized take numbers are shown in Table 6. In addition to considering estimates of the number of Start Printed Page 55664marine mammals that might be “taken” through harassment, NMFS considers other factors, such as the likely nature of any responses (e.g., intensity, duration), the context of any responses (e.g., critical reproductive time or location, migration), as well as effects on habitat, and the likely effectiveness of the mitigation.