BOEM Selects Mitigation Measures for Atlantic Seismic

The U.S. Bureau of Ocean Energy Management has published BOEM’s Record of Decision (ROD) for the Atlantic OCS Proposed Geological and Geophysical Activities, Mid-Atlantic and South Atlantic Planning Areas (AOI”), Final Programmatic Environmental Impact Statement (PEIS).  These documents select the following mitigation measures for all G & G activities in the Atlantic, including seismic surveys.

 Mitigation Measures for All G&G Activities

 Subject to site-specific analysis, the following mitigation measures apply to all G&G activities within the AOI for which BOEM authorization is required:

I .  Guidance for vessel strike avoidance.  Vessel operator, regardless of vessel size, must maintain a vigi lant watch for all marine mammals and sea turtles to avoid strikes while in transit. Speed must be reduced to 10 knots or less when within designated time/area closures for North Atlantic Right Whales (NARWs) or when mother/calf pairs, pods, or large groups of any cetaceans are observed nearby. A minimum distance of 500 meters must be kept from any NARW sighted, 100 meters from other whale species listed under the Endangered Species Act (ESA), and 50 meters from all other marine mammals and sea turtles.

2.   Guidance to avoid disturbing special areas in surveys within the AOI for oil, gas, or marine minerals, whether or not leased; and for renewable energy surveys within leased areas of the AOI.  Based on site-specific information, BOEM will require G&G activities to avoid disturbing special areas, such as sensitive benthic (seafloor) biological communities, national marine sanctuaries, historic and prehistoric sites, and cables or other infrastructure.

3.  Guidance to prevent discharge of marine debris. All vessel operators, employees, and con tractors who actively engage in G&G surveys must be briefed on trash and marine debris and made aware of their responsibility to ensure that trash and other debris is not intentionally or accidentally discharged into the sea.

4.   Guidance for military and National Aeronautics and Space Administration (NASA) coordination. All vessel and aircraft operators will be required to establish and maintain early contact and coordination with the appropriate military command headquarters or NASA points of contact.  BOEM and the Department of Defense are coordinating with each other and other agencies through interagency working groups formed to avoid conflicts and alsothrough established state-federal interagency task forces and regional planning efforts.

 Mitigation Measures for Seismic Airgun Suurveys

 The following mitigation measures apply to authorizations or seismic airgun surveys within the AOI.

1. Airgun seismic survey protocol.

a.         Acoustic exclusion zone around vessels.  All airgun seismic activities will be subject to an acoustic exclusion zone around vessels that disallows those activities if marine mammals and sea turtles are present within the zone to ensure that those animals are not exposed to sound pressure levels of 1 80 decibels…or more-the level that the National Marine Fisheries Service (NMFS) has concluded may damage marine mammal hearing. The size of the zone may vary with the source level of airguns used, but in any event the zone’s boundary can not be less than 500 meters from the source.

b.         Visual monitoring by protected species observers (PSOs) on vessels.  Visual monitoring will be required by trained PSOs during daylight hours before and during seismic surveys.

c.          Halting airgun use when animals get too close.  Airgun seismic survey activities must be shut down if a marine mammal or sea turtle enters the exclusion zone and may not be re-started until the zone has been clear for at least 60  minutes.An exception will be made for dolphins voluntarily approaching the vessel or the equipment towed, which happens frequently without apparent harm to the dolphins.

d.         Ramping-up airguns.  Airgun arrays will be required to ramp-up incrementally for at least 20 minutes before reaching maximum source level.

e.         Passive acoustic monitoring (PAM). PAM refers to use of microphones in the water to l isten for marine mammal vocal izations.  PAM will be required during all airgun surveys and will use towed or stationary hydrophones that will monitor for marine mammal vocalizations.

f.         Geographic separation of simultaneous surveys. A 40-km geographic separation distance may be required between simultaneously operating deep penetration seismic surveys within the AOI.  The use of this mitigation measure will be evaluated on a case-by-case basis.

2.   Airgun seismic survey time-area closures for NARWs.

a.         Critical habitat. NMFS has designated critical habitat for the NARW offshore the coast of southern Georgia and northern Florida.  Airgun surveys within the designated  area will be prohibited  between November  1 5 and April 1 5, when NARWs arc present to breed, give birth, and nurse cal ves.

b.          All-coast seasonal management area  (SMA).  A SMA with time closures will be observed for waters seaward from the coastline to 20 nm offshore along the entire coast of the AOI from the entrance to Delaware Bay to just south of Cape Canaveral in Florida.  G&G survey vessel speed will be limited to 10 knots or less, and airgun seismic surveys will be prohibited by BOEM during time closures to avoid migrating NARWs or NARWs with calves on wintering grounds.  The time closures for the SMA will be from November 1 to April 30 between the Delaware Bay and Brunswick, Georgia, and from November 15 through April 1 5 for the portion of the SMA south of Brunswick, including NARW critical habitat.

c.         Dynamic management areas (DMAs).   DMAs are areas that may be temporarily designated by NMFS after NARWs arc observed in those areas.  Vessel operators are required to avoid DMAs or reduce speed to 10 knots or less when transiting DMAs.  All sound sources within a DMA must cease within 24 hours of its designation.

d.         Sound limits for airgun surveys outside of time-area closures.  Survey operators will also be required to ensure that sound from surveys outside of NARW critical habitat, the SMA, or DMAs does not exceed 160 decibels at the boundaries of these areas–the limit currently advanced by NMFS as the threshold for assuring no disruption of marine mammal behavior.

3.  Airgun seismic survey time-area closure for sea turtles. To protect nesting sea turtles. which breed in the thousands at Archie Carr National Wildlife Refuge, airgun seismic surveys will be prohibited between May I and October 31  i n a zone extending to 5.9 miles offshore Brevard County, Florida.

 Mitigation Measures for High Resolution Geophysical (HRG) Surveys

The following mitigation measures apply to authorizations of HRG surveys within the AOl:

I.   Restrictions in NARW critical habitat for non-airgun HRG surveys below 30kHz. Non-airgun HRG surveys using frequencies lower than 30kHz will be prohibited in NARW critical  habitat  from November 15 to April 15, unless BOEM determines that survey information is critically needed.  In such a case, BOEM will require additional mitigation measures that may be needed to avoid impacts.

2.   Restrictions  in DMAs.  Survey vessels using HRG non-airgun sound sources in or near DMAs will be subject to the same restrictions as vessels using airguns.

3.  Acoustic exclusion zone size.  A 200-meter minimum exclusion zone for marine mammals and sea turtles will be required for HRG surveys operating at 200kHz or lower frequencies. Larger zones will be required if field observations or modeling indicate that sound pressure levels may exceed 1 80 decibels beyond 200 meters from the HRG survey activities.

4.   Acoustic exclusion zone monitoring.  Exclusion zones must be monitored by trained PSOs. If BOEM authorizes nighttime operations or if operations continue during periods of reduced visibility, then shipboard lighting and equipment must be used to enhance the PSO’s ability to visually monitor the exclusion zones, and PAM may al so be required.

5.  Notice to NMFS.  BOEM must provide NMFS with advance notice of at least 30 days before any HRG surveys begin.


Click here to read BOEM’s ROD containing these mitigation measures.



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