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Federal Register / Vol. 86, No. 106 / Friday, June 4, 2021 / Notices acoustic source is in the water, whether activated or not, a minimum of two visual PSOs must be on duty and conducting visual observations at all times during daylight hours i.e., from 30 minutes prior to sunrise through 30
minutes following sunset. Visual monitoring of the pre-start clearance zone must begin no less than 30 minutes prior to ramp-up, and monitoring must continue until one hour after use of the acoustic source ceases or until 30
minutes past sunset. Visual PSOs shall coordinate to ensure 360 visual coverage around the vessel from the most appropriate observation posts, and shall conduct visual observations using binoculars and the naked eye while free from distractions and in a consistent, systematic, and diligent manner.
PSOs shall establish and monitor the exclusion and buffer zones. These zones shall be based upon the radial distance from the edges of the acoustic source rather than being based on the center of the array or around the vessel itself.
During use of the acoustic source i.e., anytime airguns are active, including ramp-up, detections of marine mammals within the buffer zone but outside the EZ shall be communicated to the operator to prepare for the potential shutdown of the acoustic source. Visual PSOs will immediately communicate all observations to the on duty acoustic PSOs, including any determination by the PSO regarding species identification, distance, and bearing and the degree of confidence in the determination. Any observations of marine mammals by crew members shall be relayed to the PSO team. During good conditions e.g., daylight hours;
Beaufort sea state BSS 3 or less, visual PSOs shall conduct observations when the acoustic source is not operating for comparison of sighting rates and behavior with and without use of the acoustic source and between acquisition periods, to the maximum extent practicable.
Visual PSOs may be on watch for a maximum of 4 consecutive hours followed by a break of at least one hour between watches and may conduct a maximum of 12 hours of observation per 24-hour period. Combined observational duties visual and acoustic but not at same time may not exceed 12 hours per 24-hour period for any individual PSO.
Passive Acoustic Monitoring Acoustic monitoring means the use of trained personnel sometimes referred to as passive acoustic monitoring PAM
operators, herein referred to as acoustic PSOs to operate PAM equipment to acoustically detect the presence of marine mammals. Acoustic monitoring
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involves acoustically detecting marine mammals regardless of distance from the source, as localization of animals may not always be possible. Acoustic monitoring is intended to further support visual monitoring during daylight hours in maintaining an EZ
around the sound source that is clear of marine mammals. In cases where visual monitoring is not effective e.g., due to weather, nighttime, acoustic monitoring may be used to allow certain activities to occur, as further detailed below.
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. Acoustic monitoring can be used in addition to visual observations to improve detection, identification, and localization of cetaceans. The acoustic monitoring would serve to alert visual PSOs if on duty when vocalizing cetaceans are detected. It is only useful when marine mammals vocalize, but it can be effective either by day or by night, and does not depend on good visibility. It would be monitored in real time so that the visual observers can be advised when cetaceans are detected.
The R/V Langseth will use a towed PAM system, which must be monitored by at a minimum one on duty acoustic PSO beginning at least 30 minutes prior to ramp-up and at all times during use of the acoustic source. Acoustic PSOs may be on watch for a maximum of 4
consecutive hours followed by a break of at least one hour between watches and may conduct a maximum of 12
hours of observation per 24-hour period.
Combined observational duties acoustic and visual but not at same time may not exceed 12 hours per 24-hour period for any individual PSO.
Survey activity may continue for 30
minutes when the PAM system malfunctions or is damaged, while the PAM operator diagnoses the issue. If the diagnosis indicates that the PAM system must be repaired to solve the problem, operations may continue for an additional 5 hours without acoustic monitoring during daylight hours only under the following conditions:
Sea state is less than or equal to BSS 4;
No marine mammals excluding delphinids detected solely by PAM in the applicable EZ in the previous 2
hours;
NMFS is notified via email as soon as practicable with the time and location in which operations began
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occurring without an active PAM
system; and Operations with an active acoustic source, but without an operating PAM
system, do not exceed a cumulative total of 5 hours in any 24-hour period.
Establishment of Exclusion and PreStart Clearance Zones An EZ is a defined area within which occurrence of a marine mammal triggers mitigation action intended to reduce the potential for certain outcomes, e.g., auditory injury, disruption of critical behaviors. The PSOs would establish a minimum EZ with a 500-m radius. The 500-m EZ would be based on radial distance from the edge of the airgun array rather than being based on the center of the array or around the vessel itself. With certain exceptions described below, if a marine mammal appears within or enters this zone, the acoustic source would be shut down.
The pre-start clearance zone is defined as the area that must be clear of marine mammals prior to beginning ramp-up of the acoustic source, and includes the EZ plus the buffer zone.
Detections of marine mammals within the pre-start clearance zone would prevent airgun operations from beginning i.e., ramp-up.
The 500-m EZ is intended to be precautionary in the sense that it would be expected to contain sound exceeding the injury criteria for all cetacean hearing groups, based on the dual criteria of SELcum and peak SPL, while also providing a consistent, reasonably observable zone within which PSOs would typically be able to conduct effective observational effort.
Additionally, a 500-m EZ is expected to minimize the likelihood that marine mammals will be exposed to levels likely to result in more severe behavioral responses. Although significantly greater distances may be observed from an elevated platform under good conditions, we believe that 500 m is likely regularly attainable for PSOs using the naked eye during typical conditions. The pre-start clearance zone simply represents the addition of a buffer to the EZ, doubling the EZ size during pre-clearance.
An extended EZ of 1,500 m must be enforced for all beaked whales. No buffer of this extended EZ is required.
Pre-Start Clearance and Ramp-Up Ramp-up sometimes referred to as soft start means the gradual and systematic increase of emitted sound levels from an airgun array. Ramp-up begins by first activating a single airgun of the smallest volume, followed by doubling the number of active elements
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