Abstract
This report provides a summary of all protected species monitoring and mitigation activities for geophysical surveys (Surveys) conducted under the 2019 Ørsted Incidental Harassment Authorization (NMFS 2019), valid for the one-year period from 26 September 2019 through 25 September 2020. The IHA covered all high-resolution geophysical (HRG) survey work in four developing wind farms in New England waters, within and near the Bureau of Ocean Energy Management (BOEM) Commercial Leases of Submerged Lands for Renewable Energy Development on the Outer Continental Shelf OCS A-0486, OCS-A 0487, and OCS-A 0500 (Lease Areas).
Protected species observers (PSOs) aboard eight different HRG survey vessels completed a total of 103,186 kilometers (km), representing 15,919 hours (h) of Monitoring Effort on the Surveys. Monitoring Effort was split approximately equally between Daylight versus Darkness, and in areas Inside versus Outside the three BOEM Lease Areas covered by the NMFS IHA.
During the Surveys, there was a total of 2,106 protected species groups/detections composed of an estimated 15,751 individuals. Short-beaked common dolphin and humpback whale were the most frequently detected species. A total of five North Atlantic right whale (NARW) individuals were seen in five different detection events. Most marine mammal detections occurred while HRG Sound was being produced below 200 kilohertz (kHz; HRG Sound On). Fifty sea turtles were detected, split equally between periods of HRG Sound On versus Off.
PSOs estimated only 8% of marine mammal detections were observed to change behavior while HRG Sound was On. The majority of these were short-beaked common dolphins changing direction, which is not considered an avoidance or disturbance behavior. Mysticete whales were observed to blow more when HRG Sound was On, and the median closest observed point of approach (CPA) was greater for all marine mammal species groups when HRG Sound was On versus Off. HRG Sound had no apparent effect on sea turtle behavior. These results indicate that any potential reactions of protected species to HRG Sound were localized and low-level.
The majority of the 259 total mitigation requests made by PSOs were for a shutdown (n=149) of electromechanical equipment operating below 200 kHz, or for a delay (n=104) of energizing this equipment. PSOs requested mitigation pertaining to vessel strike avoidance measures on 33 occasions. Short-beaked common dolphins were the primary cause of PSO-requested shutdowns and also for delays during pre-clearance, likely due to their curiosity about vessel activity. All mitigation requests were implemented quickly and effectively, helping to safeguard protected species from ship strikes and potential physical harm or behavioral disturbance from HRG equipment noise.
After excluding all individual marine mammal detections within the 180-m Level B isopleth that resulted in an immediate shutdown, as well as other individuals exposed to lower- Smultea Sciences 2019-2020 Ørsted IHA PSO Technical Report 25 December 2020 Smultea Sciences confidential and proprietary. 2 energy sounds sources, the number of estimated Level B exposures for each species was less than the number of Level B incidental takes authorized by NMFS in Ørsted’s IHA.
An estimated nine individual, non-delphinoid cetaceans were detected within the 180-m Level B harassment zone while HRG sound sources were operating below 200 kHz and for which a shutdown was not implemented. However, none of these individuals came within the 100-m EZ stipulated within the IHA, thus no mitigation was required or requested by PSOs. Although all appropriate mitigation and shutdown protocols were followed, it is possible these individuals were exposed to impulsive sound levels above 160 decibels (dB) root mean square (RMS) for brief durations.
Mitigation and monitoring measures defined in the 2019 Ørsted IHA and BOEM Leases were properly implemented by PSOs throughout the Surveys and considered effective to safeguard protected species.