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Federal Register / Vol. 86, No. 157 / Wednesday, August 18, 2021 / Notices
times during daylight hours i.e., from 30 minutes prior to sunrise through 30
minutes following sunset. Visual monitoring of the EZ and buffer zone must begin no less than 30 minutes prior to ramp-up and 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 EZ and buffer zone. 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.
During use of the airgun i.e., anytime the acoustic source is active, including ramp-up, detections of marine mammals within the buffer zone but outside the EZ should 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 four 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.
Establishment of Exclusion and Buffer Zones An EZ is a defined area within which occurrence of a marine mammal triggers
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mitigation action intended to reduce the potential for certain outcomes, e.g., auditory injury, disruption of behavioral patterns. The PSOs would establish a minimum EZ with a 500- or 100-m radius, during use of the high-energy and low-energy arrays, respectively, for all species except bowhead whales. The 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.
The EZs are intended to be precautionary in the sense that they 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, the EZs are 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 these distances are likely regularly attainable for PSOs using the naked eye during typical conditions.
An extended EZ of 1,500/500 m must be implemented for all bowhead whales during high-energy and low-energy survey effort, respectively, because of their importance to subsistence hunters and protected status. No buffer of this extended EZ is required.
Pre-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 in stages until the full complement of an arrays airguns are active. Each stage should be approximately the same duration, and the total duration should not be less than approximately 20
minutes for high-energy airgun arrays.
Ramp-up for the low-energy array, which includes only two elements, may be shorter. The intent of pre-clearance observation 30 minutes is to ensure no protected species are observed within the buffer zone prior to the beginning of ramp-up. During pre-clearance is the only time observations of protected species in the buffer zone would prevent operations i.e., the beginning of ramp-up. The intent of ramp-up is to warn protected species of pending seismic operations and to allow sufficient time for those animals to leave
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the immediate vicinity. A ramp-up procedure, involving a step-wise increase in the number of airguns firing and total array volume until all operational airguns are activated and the full volume is achieved, is required at all times as part of the activation of the acoustic source. All operators must adhere to the following pre-clearance and ramp-up requirements:
The operator must notify a designated PSO of the planned start of ramp-up as agreed upon with the lead PSO; the notification time should not be less than 60 minutes prior to the planned ramp-up in order to allow the PSOs time to monitor the EZ and buffer zone for 30 minutes prior to the initiation of ramp-up pre-clearance;
Ramp-ups shall be scheduled so as to minimize the time spent with the source activated prior to reaching the designated run-in;
One of the PSOs conducting preclearance observations must be notified again immediately prior to initiating ramp-up procedures and the operator must receive confirmation from the PSO
to proceed;
Ramp-up may not be initiated if any marine mammal is within the applicable EZ or buffer zone. If a marine mammal is observed within the applicable EZ or the buffer zone during the 30 minute pre-clearance period, ramp-up may not begin until the animals has been observed exiting the zones or until an additional time period has elapsed with no further sightings 15 minutes for small odontocetes and pinnipeds, and 30 minutes for all mysticetes and all other odontocetes, including large delphinids, such as beluga whales and killer whales;
Ramp-up shall begin by activating a single airgun of the smallest volume in the array and shall continue in stages by doubling the number of active elements at the commencement of each stage, with each stage of approximately the same duration. Duration shall not be less than 20 minutes for high-energy arrays. The operator must provide information to the PSO documenting that appropriate procedures were followed;
PSOs must monitor the relevant EZ
and buffer zone during ramp-up, and ramp-up must cease and the source must be shut down upon detection of a marine mammal within the applicable EZ. Once ramp-up has begun, detections of marine mammals within the buffer zone do not require shutdown, but such observation shall be communicated to the operator to prepare for the potential shutdown;
Ramp-up may occur at times of poor visibility, including nighttime, if
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