[Federal Register Volume 60, Number 200 (Tuesday, October 17, 1995)]
[Notices]
[Pages 53752-53760]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25722]
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[[Page 53753]]
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[I.D. 053095D]
Small Takes of Marine Mammals Incidental to Specified Activities;
Offshore Seismic Activities in Southern California
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of issuance of an incidental harassment authorization.
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SUMMARY: In accordance with provisions of the Marine Mammal Protection
Act (MMPA) as amended, notification is hereby given that an Incidental
Harassment Authorization to take small numbers of cetaceans by
harassment incidental to conducting a three-dimensional (3-D) seismic
survey in the Santa Ynez Unit (SYU), located in the western portion of
the Santa Barbara Channel, offshore California, in Federal waters has
been issued to the Exxon Company, U.S.A., Thousand Oaks, CA, for a
period of approximately 2 months.
EFFECTIVE DATE: This authorization is effective from October 11, 1995
through December 31, 1995.
ADDRESSES: The application, authorization, programmatic environmental
assessment (EA), and reference lists are available from the following
offices: Marine Mammal Division, Office of Protected Resources, NMFS,
1315 East-West Highway, Silver Spring, MD 20910 and the Southwest
Region, NMFS, 501 West Ocean Blvd. Long Beach, CA 90802.
A copy of the EA for the 3-D seismic survey in the SYU is available
from the Minerals Management Service (MMS), Pacific Region, 770 Paseo
Camarillo, Camarillo, CA 93010.
FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead, Office of
Protected Resources at 301-713-2055, or Irma Lagomarsino, Southwest
Regional Office at 310-980-4016.
SUPPLEMENTARY INFORMATION:
Background
Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1361 et seq.) directs
the Secretary of Commerce to allow, upon request, the incidental, but
not intentional taking of marine mammals by U.S. citizens who engage in
a specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and regulations are
issued.
Permission may be granted if NMFS finds that the taking will have a
negligible impact on the species or stock(s); will not have an
unmitigable adverse impact on the availability of the species or
stock(s) for subsistence uses; and the permissible methods of taking
and requirements pertaining to the monitoring and reporting of such
taking are set forth.
On April 30, 1994, the President signed Public Law 103-238, The
MMPA Amendments of 1994. One part of this law added a new subsection
101(a)(5)(D) to the MMPA to establish an expedited process by which
citizens of the United States can apply for an authorization to
incidentally take small numbers of marine mammals by harassment for a
period of up to 1 year. The MMPA defines ``harassment'' as:
* * * any act of pursuit, torment, or annoyance which (a) has the
potential to injure a marine mammal or marine mammal stock in the
wild; or (b) has the potential to disturb a marine mammal or marine
mammal stock in the wild by causing disruption of behavioral
patterns, including, but not limited to, migration, breathing,
nursing, breeding, feeding, or sheltering.
New subsection 101(a)(5)(D) establishes a 45-day time limit for
NMFS review of an application followed by a 30-day public notice and
comment period on any proposed authorizations for the incidental
harassment of small numbers of marine mammals. Within 45 days of the
close of the comment period, NMFS must either issue or deny issuance of
the authorization.
On May 11, 1995, NMFS received an application from Exxon requesting
an authorization for the harassment of small numbers of certain species
of cetaceans incidental to conducting a 3-D seismic survey within the
SYU, located in the western portion of the Santa Barbara Channel, off
Southern California, in U.S. waters. The species requested are as
follows: Blue whale (Balaenoptera musculus), fin whale (Balaenoptera
physalus), sei whale (Balaenoptera borealis), humpback whale (Megaptera
novaeangliae), minke whale (Balaenoptera acutorostrata), Bryde's whale
(Balaenoptera edeni), gray whale (Eschrichtius robustus), sperm whale
(Physeter macrocephalus) and pygmy sperm whale (Kogia breviceps).
Exxon's survey will cover an area of approximately 117 mi2
(303 km2) of the outer continental shelf and will require
approximately 45-60 days, commencing in late October 1995, to complete.
The survey will provide subsurface data that will enable Exxon to more
accurately assess the oil and gas reservoirs in order to optimally
locate future development wells from existing platforms.
In addition to a press release, notices were published in
newspapers of general circulation in Santa Barbara and Ventura
Counties, the areas adjacent to the SYU survey area. Also a notice of
receipt of Exxon's application and the proposed authorization were
published in the Federal Register (June 7, 1995, 60 FR 30066) and a 30-
day public comment period was provided on the application and proposed
authorization. The comment period closed on July 7, 1995. During the
comment period, 9 letters were received. Beginning September 13, 1995,
more than 2 months after the comment period closed, NMFS received
several additional comments. NMFS is under no obligation to accept
comments received after close of the comment period. Nevertheless, NMFS
considered the concerns raised by the late comments, and because NMFS
believed that valid points had been made, took them into consideration
in finalizing the incidental harassment authorization. Comments
relative to Exxon's incidental harassment authorization request are
discussed below. Other than information necessary to respond to the
comments, additional background information on the activity and request
can be found in the above-mentioned documents and does not need to be
repeated here.
Comments and Responses
Activity Concerns
Comment 1. One commenter had concerns that neither the application
nor the proposed authorization addressed the operation of the 3-D
seismic array in sufficient detail, thereby preventing a detailed
analysis of the impacts. This same commenter questioned the duty cycle
and that signals with quick rise and fall times do not allow the animal
time to auditorially accommodate the noise.
Response. The commenter is correct that there was absent from the
discussion any mention of the peak source level for the seismic array.
However, like the commenter, NMFS used data provided in Richardson et
al. (1991)1 and Malme et al. (1984). These references indicate
that a seismic array would have a sound pressure level (SPL) of between
226 dB and 239 dB (re 1 Pa) at 1 meter (m) from the source.
Information not available at the time of receipt of the application
indicates that air gun arrays may produce broadband peak source levels
as high as 240-250 dB (re 1 Pa), but that much of this total
output is directed downward; horizontal
[[Page 53754]]
propagation is 230-235 dB (MMS, 1995). Air gun pulse components are
strongest around 50-100 Hz, although there is considerable energy in
the 20-250 Hz range (Richardson and Malme, 1993 as cited in MMS, 1995).
Exxon's contractor for the surveys, who had not been selected at the
time of the proposed authorization's publication, has indicated that
his seismic arrays will have a maximum output of 215 dB at a distance
of 8 m and will result in fewer west-east transects (55 v 64) than
estimated in the application and proposed authorization. This array
will therefore result in lower sound pressure levels at a given
distance from the source than was predicted in the proposal.
\1\A list of references used in this document can be obtained by
writing to the address provided above (see ADDRESSES).
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While the proposed authorization noted that the 195 dB isopleth
would be located approximately 300 ft (91.5 m) from the source,
recalculations (based upon the 20LogR transmission loss model),
indicate that 195 dB will occur at 246 ft (75 m) from the source. This
is the area within which NMFS was originally concerned that temporary
or permanent threshold-shift (TTS/PTS) injury potentially could take
place (if the animal remained in this relatively small area for any
length of time and had the ability to hear in the frequencies of the
source) and therefore, in order to protect all species of marine
mammals from potential auditory injury, the seismic array must be
turned off whenever any marine mammals are sighted within the area and/
or must not be powered up whenever marine mammals are within the area.
NMFS recognizes that some marine mammals are deep divers and may not be
visible on the surface, and that night-time operations will limit
observations outside the safety zone. NMFS is confident however, that
no marine mammals will remain within this area because (1) The vessel
is underway at a speed of approximately 5 knots (9.26 km/hr), less than
the normal swimming speed of marine mammals, allowing them sufficient
advance notice of the seismic array (if they hear the noise) and, if it
disturbs them, to move away from the source; (2) it is presumed that
water turbulence from the vessel, the paravanes and streamer array will
tend to deter marine mammals from approaching the source even if they
do not hear the source; and (3) the requirement to ramp-up whenever the
source is turned on.
The seismic source will consist of dual air gun arrays deployed
approximately 120 ft (37.5 m) apart and fired alternately to acquire
separate records. Each array will consist of 18 guns of different
strengths. Each array will transmit every 8 to 9 seconds (depending
upon vessel speed), while the vessel is on a trackline, creating a
regular series of strong noise impulses, with short pulses separated by
silent periods lasting 5-15 seconds, depending on survey type and depth
of target strata. While the science is unclear on the relationship
between the duty cycle of a seismic source and the potential for
auditory damage to a marine mammal, because of the slow vessel speed,
and the requirements to both terminate the source whenever marine
mammals are within the safety zone and to employ ramp-up, NMFS believes
that the likelihood that a marine mammal would voluntarily remain in
close proximity to the source in the presence of pain or annoyance, and
thereby be seriously injured by the towed acoustic array, is remote.
Marine Mammal Species Impacts
Comment 2. Three commenters were concerned that seismic surveys
disturbed other marine mammal species in addition to the large whales,
especially the harbor seal and the California sea lion. Also, comments
were received after the close of the comment period that (1) Seismic
arrays produced seismic noise in frequencies up to 1 kHz at levels
sufficient to harass odontocetes and pinnipeds and (2) that the correct
transmission loss model for the seismic area was not 20LogR but more
likely 15 or 17LogR which would affect both designated safety zones and
the number of marine mammals affected. Based upon measurements made in
the Beaufort Sea in 1993, one commenter believed that a 160 dB isopleth
should extend 27.4 km, not 5.2 km as proposed.
Response. NMFS would like to clarify for reviewers that being able
to hear certain sounds (noise) does not necessarily mean that a marine
mammal is being physiologically stressed (harassed) by that sound. In
addition, when noise is frequent, marine mammals may habituate to it
once the determination is made that injury or harm does not result.
In order to be detectable by a marine mammal, noise needs to be
greater than ambient within the same frequency band as the animal's
hearing range. The further outside the species' principal (best)
hearing range the noise occurs, the greater (louder) sounds need to be
in order to be detectable, bothersome, or injurious.
Seismic airgun arrays emit pulsed energy at frequencies in the 20
to 250 Hz range, with a peak SPL usually between 226 dB and 239 dB (re
1 Pa) at 1 m. Exxon calculated (and the manufacturer has
confirmed) that its seismic array would have an SPL of 215 dB at a
distance of 8 m from the geometric center of the source (or
approximately 1 m from the outside of the array) and based its
transmission loss calculations using the 20LogR model, even though
Malme et al. (1986) indicated that for offshore California seismic
work, a less conservative, 25LogR model was appropriate. The 8 m/20LogR
model indicated SPLs would attenuate to approximately 195 dB at 246 ft
(75 m), 190 dB at 451 ft (137.5 m), 180 db at 1,476 ft (450 m) and 160
dB at 2.84 nautical miles (nm) (5.2 km). Based upon comments that the
20LogR transmission loss model was not appropriate for coastal
California waters, Exxon has again recalculated transmission loss
estimates based upon an industry standard of 1 m from geometric center
of the source. This model indicates that SPLs would attenuate
approximately as follows:
Distance From Source (ft/m)
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Sound level 20LogR 17LogR 15LogR
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195 dB...................... 32.9/10................... 49.2/15................... 72.1/22
190 dB...................... 58.4/17.8................. 96.8/29.5................. 152.4/46.5
180 db...................... 187.0/57.................. 377.3/115................. 705.4/215
170 dB...................... 587.3/179................. 1492.8/455................ 3280.8/1000
160 dB...................... 1837.2/560................ 5643.0/1,720.............. 15419.8/4700
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As these distances are significantly less than the distances proposed
earlier for 8m/20LogR, NMFS has determined that the more cautious
approach, using 8 m/20LogR model, should be used for this
authorization. The commenter who
[[Page 53755]]
suggested that 1993 Beaufort Sea survey data should be used
acknowledged that his model may not be ``completely accurate for the
Santa Barbara Channel,'' but believed it was appropriate for planning
purposes. NMFS is unaware of the parameters involved with the Beaufort
Sea measurements (e.g., water temperature, depth, bottom topography,
ice cover), but in general those characteristics are quite different
from those off Southern California.
In the proposed authorization, NMFS stated that dolphin, porpoise,
seal, and sea lion hearing is believed to be poor at frequencies less
than 1,000 Hz, and thus it is unlikely that the airgun noise would
significantly affect them. One commenter correctly pointed out that
``significantly affect a marine mammal'' is not the appropriate
criterion, and that the appropriate criterion is that the activity have
a negligible impact. This commenter recommended NMFS provide a more
thorough rationale for the determination that species other than large
whales will not be taken by harassment incidental to the seismic
surveys and that the takings of large whales will be limited to
harassment.
Within the pinniped suborder, Schusterman et al. (1967) have
determined that none of the species tested to date have exhibited good
hearing capabilities at low frequencies, although the northern elephant
seal, California sea lion, and harbor seal appear to have some
communication ability within the upper low-frequency band (100-1,000
Hz). Underwater audiograms indicate that pinnipeds and odontocetes are
particularly sensitive to sound with frequencies in the 2-12 kHz range
(Richardson et al., 1991). Seals and sea lions have thresholds of
roughly 60 to 80 dB (re 1 Pa) in the range of best hearing.
Phocid seals have lower thresholds and a wider frequency range of
hearing than otariid seals. Pinniped hearing in sub-1 kHz range varies
from 85 dB at 1 kHz to 114 dB at 250 Hz for the California sea lion,
70-85 dB at 1 kHz for the harbor seal, and 95 dB at 1 kHz for the
northern fur seal (Richardson et al., 1991). No information has been
reported concerning the in-water hearing of northern elephant seals
(Richardson et al., 1991), although Schusterman (as cited in Advanced
Research Projects Office, 1995) believes they may have mid- to low-
frequency hearing ability.
No studies have focused on pinniped reaction to underwater noise
from pulsed, seismic arrays in open water (Richardson et al., 1991), as
opposed to in-air exposure to continuous noise. However, assuming an
SPL needed to be 80-100 dB over its threshold in order to cause
annoyance and 130 dB for injury (pain), as is the current thought based
upon human studies (ARPA, 1995), it appears unlikely that pinnipeds
would be harassed or injured by low frequency sounds from a seismic
source unless they were within close proximity of the array (114
dB2 + 80 dB = 190 dB (harassment); 114 dB2 + 130 dB = 244 dB
(injury)). At the upper end of the seismic array's frequency (1 kHz),
sufficient energy to cause harassment would occur at a distance of only
1-3 m from the source while TTS injury takes would not occur (70 dB
(harbor seal) - 85 dB (California sea lion) + 80 dB = 150-165 dB
(harassment); 70 dB (harbor seal) - 85 dB (California sea lion) + 130
dB = 200-215 dB (injury)).
\2\Extrapolated from Figure 7.2 in Richardson et al. (1991).
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For permanent injury, marine mammals would need to remain in the
high noise field for extended periods of time. Existing evidence also
suggests that, while they may be capable of hearing sounds from seismic
arrays, seals and sea lions appear to tolerate intense pulsatile
sounds, without known effect, once they learn that there is no danger
associated with the noise (see for example, NMFS/WDFW, 1995). In
addition, they will apparently not abandon feeding or breeding areas
due to exposure to these noise sources (Richardson et al., 1991) and
may habituate to certain noises over time. Since seismic work is common
in southern California waters, pinnipeds have previously been exposed
to seismic noise, and may not react to it. However, because the
evidence indicates that pinnipeds could be incidentally harassed at an
SPL of 190 dB or greater, and because Exxon has not requested an
incidental harassment authorization for pinnipeds, NMFS will require,
as part of the authorization, that a safety zone around the source be
established at the 190 dB isopleth or 451 ft (137.5 m) from the source.
For added protection, this zone will include the entire area from the
stern of the vessel out to the paravanes or approximately 500 ft (152.4
m) from the source.
For odontocetes, based upon the best scientific evidence available,
NMFS concludes that the hearing of dolphins, porpoises and other small
whales that inhabit the Channel Islands area is poor at frequencies
less than 1,000 Hz, and thus it is unlikely that the airgun noise would
affect them. While odontocetes can hear sounds over a very wide range
of frequencies, from as low as 75-125 Hz in bottlenose dolphins and
belugas (Johnson, 1967; Awbrey et al., 1988) to 105-150 kHz in several
other species (Richardson et al., 1991), underwater audiograms indicate
that odontocetes hear best at frequencies above 10 kHz. However, none
of the seismic source frequencies will be within the dominant
frequencies used by odontocetes for vocalization (Richardson et al.,
1991).
In the range of best hearing (10 kHz-90 kHz), odontocetes have
thresholds in the range of 40 to 60 dB re 1 Pa. In the absence
of noise, bottlenose dolphins can detect a signal of about 41-42 dB at
various frequencies between 10 kHz and 100 kHz (Johnson, 1967, 1968).
For frequencies from 100 Hz to roughly 1000 Hz however, hearing
thresholds range from 130 dB to 90 dB re 1 Pa, suggesting the
potential for an increased tolerance for low frequency sound. Other
odontocete species appear to have similar threshold frequencies (see
Richardson et al., 1991). If one accepts one commenter's premise and
Richardson et al.'s (1991) conclusion, that, based upon studies on
humans, SPLs of 80-100 dB over threshold are necessary in order to
cause annoyance and 130 dB for injury (pain) in odontocetes, most
odontocetes would probably need to be almost adjacent to the seismic
source, and intentionally remain there, in order to be affected by the
seismic array (110 dB3 + 80 dB (harassment) = 190 dB; 110 dB + 130
dB (injury) = 240 dB). At the upper end of the seismic array's
frequency (1 kHz), sufficient energy would not occur that would cause
either harassment or TTS injury takes to occur (90 dB + 80 dB = 170 dB
(harassment); 90 dB + 130 dB = 220 dB (injury)).
\3\ Extrapolated from Figure 7.1 in Richardson et al. (1991).
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However, NMFS cautions that testing on the similarity between
hearing capabilities between humans and marine mammals still needs to
be conducted before more than hypothetical conclusions can be drawn.
Similar to pinnipeds, because the evidence indicates that odontocetes
(other than the sperm whale) could be incidentally harassed at an SPL
of 190 dB or greater, and because Exxon has not requested an incidental
harassment authorization for odontocetes (other than the sperm whale),
NMFS will require, as part of the authorization, that a safety zone
around the source be established at the 190 dB isopleth or 451 ft
(137.5 m) from the source. For added protection, this zone will include
the entire area from the stern of the vessel out to the paravanes, or
approximately 500 ft (152.4 m) from the source.
Therefore, whether or not the above mentioned marine mammal species
can hear seismic array sounds, their
[[Page 53756]]
estimated area of potential harassment and/or auditory damage remains
entirely within the area bounded by the vessel, the paravanes and the
streamer cables. As Exxon will be required to turn off the array if any
species of marine mammal is sighted within this new 500-ft (152.4 m)
safety zone, to ramp-up the array slowly (see below), and, if any
marine mammals are observed within the 500-ft (152.4-m) safety zone,
delay operations until all marine mammals are outside the zone, it is
unlikely that pinnipeds or odontocete cetaceans (except sperm whales)
will be incidentally harassed by the seismic array and therefore, an
authorization is not needed for these species. It can also be presumed
that any marine mammals that consistently remain in the vicinity of, or
swim along with, the vessel or its equipment, are not being harassed by
the vessel or the array.
For mysticete and sperm whales, NMFS has reviewed the evidence and
has determined that, because an authorization for serious injury has
not been requested for these species, a no-injury safety zone should be
established that, based upon the best evidence, would preclude injury.
NMFS has determined that injury may occur at a level of 180 dB or
greater and has therefore established, through the authorization, a
safety zone for these species at a distance of 1,476 ft (450 m) from
the source. While there are indications, based upon the Heard Island
assessment, that injury may occur at the 160 dB SPL, because the 160 dB
SPL is where Malme et al. (1984) noted 10 percent avoidance behavior
for gray whales, and injury appears to be about 30 dB higher than the
onset of harassment, 160 dB may be an overly conservative level for
injury takes. However, because mysticete sensitivity is likely greater
than that of odontocetes, 190 dB appears too high for these species.
Therefore, a safety zone established at the 180 dB level appears
warranted.
Comment 3. Several commenters noted that Exxon's survey period was
for 60 days but that NMFS' proposed authorization was for a period of 1
year. These commenters recommended either that the period of time not
extend past the period when the gray whale migration begins, because
the analyses have not been conducted to assess the risk of adversely
affecting this migration or that the authorization period end at the
same time (December 31st) that the California Air Pollution Control
District's (APCD) permit for the survey. One of these commenters also
questioned the calculated level of take of gray whales (and other
species), noting that, for gray whales, the level depended upon the
timing of the survey and, therefore, might be greater than proposed.
For other species, the commenter was concerned that the proposed
authorization used average densities along the coast of California and
may seriously over- or under-estimate abundance.
Response. While one commenter is correct that NMFS originally
proposed to issue a 1-year authorization, NMFS has accepted the other
commenter's suggestion and will limit the authorization to a period of
validity of the APCD permit (December 31, 1995).
In its proposed authorization, NMFS assumed that gray whales could
be incidentally harassed if the survey extended into the gray whale
migratory period (southbound--mid-December through early February;
northbound--mid-February through May) and therefore, included that
species under the proposed incidental harassment authorization. Because
Barlow (1995) did not observe any gray whales during his summer/fall
ship surveys, incidental harassment levels were based upon fall/winter
gray whale density calculations found in Forney et al. (1995).
It should be noted that for incidental harassment takings, NMFS
does not consider its calculations to be quotas, but only a guide for
making the MMPA negligible impact determinations. The two tables in the
proposed authorization indicate that, based upon density calculations
in Forney et al. (1995), NMFS estimated that, if the survey extended
into the latter part of December, on average, 11 gray whales could be
within the area at any one time. Because of the method of operation of
the seismic array (as explained in the proposed authorization), NMFS
has calculated that there could be 341 incidental harassment takings of
gray whales, but that this level could increase or decrease somewhat
depending upon the time of the year, pod size, and the actual location
of the seismic vessel (onshore/offshore). This number may vary also due
to the time of the survey in relation to gray whale migration, if the
survey ends early, the number of harassments would be lower than it the
survey continued into the peak migration period in late January.
However, whether the estimate is an under- or over-estimate, with a
migration rate of approximately 3-4 mi/hr (5.5-7.7 km/hr), an
individual gray whale would be expected to be harassed only during a
single-line transect by the vessel and the length of time the animal is
exposed to the noise would depend upon its direction and distance in
relation to the seismic vessel's direction and speed and any action the
animal might take to avoid the noise. Therefore, although the potential
exists that the seismic array noise could result in gray whale
harassments, and although Exxon will make every effort to complete the
survey prior to the start of the gray whale period, an authorization
remains necessary for this species because of the possibility of survey
delays.
During their southbound migration, gray whales migrate near shore
along the coast of North America from Alaska to central California. In
1993 and 1994, 95.6 percent and 98.7 percent of the southbound gray
whales passed within 3 nm (5.6 km) of the Granite Canyon area of
central CA (Withrow et al., 1995). After passing Point Conception,
California, Rice et al. (1984) believed the majority of the animals
took a more direct offshore route across the southern California Bight
to northern Baja California. This route passes Santa Rosa and San
Nicolas islands, the Tanner and Cortes banks and into Mexican waters
(MMS, 1992), well away from Exxon's seismic survey area. Other routes
include the nearshore route which follows the mainland coast of
California, and the inshore route which passes through the northern
Channel Island chain to Santa Catalina or San Clemente Island and on
into Mexico. Although seismic array noise may be detectable to those
gray whales using the offshore and inshore routes, the noise levels at
those distances are not expected to result in any behavioral
modification or require animals to deviate from their planned migratory
path. Therefore, it is anticipated that only those gray whales on the
nearshore route would come into the vicinity of the seismic array and
potentially be disturbed by it.
Assuming that nearshore migratory animals would be within 3 nm (5.6
km) (Withrow et al., 1995) of the coastline as in central California,
this portion of the population could potentially be subject to
disturbance by seismic noise if the survey continued into the migratory
period. However, even though NMFS believes that few gray whales will be
migrating through the area prior to the time the authorization expires
on December 31, 1995, and therefore any harassment takings that do
occur would have only a negligible impact on the eastern Pacific stock,
in order to ensure that those early migratory gray whales have an
unimpeded migratory corridor, NMFS will require, as part of the
authorization, that an NMFS biologist be on board the seismic and/or
another auxiliary support vessel to monitor gray whale behavior. This
individual would
[[Page 53757]]
have authority, under the authorization, and with the concurrence of
the Regional Director, to modify or terminate the authorization if this
individual determines that gray whales are not able to migrate through
the SYU area.
Comment 4. One commenter was concerned about other potential causes
of incidental harassment or other forms of taking by, for example,
entanglement in streamer cables, vessel noise, or support vessels and
aircraft. Another commenter believed that disturbance by whale watch
vessels circling the animals was more likely than disturbance by a
seismic array.
Response. All vessels create underwater noise that is potentially
detectable by marine mammals and, based upon distance between the
mammal and the source, may have the potential to cause disturbance to
the animal. If owners or operators of these vessels (other than
commercial fishing vessels) believe that their vessels may be harassing
marine mammals, they should apply for incidental harassment
authorizations. However, the operation of one or two seismic and
support vessels or aircraft for a 45- to 60-day period is expected to
have a negligible impact on marine mammals. Vessel noise is likely to
be indistinguishable from the noise caused by the approximately 19,800
round trips annually by vessels, other than commercial-fishing boats,
into Los Angeles/Long Beach (LA/LB) harbor. It should be noted that the
southwestern portion of the survey area is adjacent to the LA/LB
shipping lanes and, therefore, is already subject to anthropogenic
noise. To avoid additional harassment authorizations, except in
emergency situations, aircraft supplying the seismic vessels are
requested to maintain an altitude of 1,000 ft (305 m) until within
3,038 ft (.5 nm; 926 m) of the seismic vessel, unless conducting
surveys for marine mammals.
The streamer array, along which the passive hydrophones are
located, will consist of 6 cables in parallel. The individual cables
will be 9,840 ft (3,000 m) long and spaced 246 ft (75 m) apart,
typically towed at a depth of 16.4 to 32.8 ft (5 to 10 m) below the
water surface. Hydrophones are attached along the cable and paravanes
will be deployed to separate the streamer arrays. The cables have a
diameter of 3.5-4 inches (8.9 to 10.2 cm); therefore, it is very
unlikely that a marine mammal would become entangled in one. More
likely, the presence of the vessel and the water turbulence from the
paravane and streamer cables will provide a zone around the source that
marine mammals will not enter. In addition, because of the slow ship
speed and resultant water turbulence and noise, it is extremely
unlikely that any marine mammals would be struck and thereby injured or
killed by the seismic vessel.
Mitigation and Monitoring Concerns
Comment 5. Two commenters were concerned that the criterion for the
Acoustic Thermography of Ocean Climate (ATOC) project having a
potential to cause harassment has been established at 120 dB, while the
3-D seismic survey's zone of influence (ZOI) was proposed for 160 dB.
Another commenter questioned whether some marine mammals would hear the
seismic pulse outside the 160 dB isopleth since Tyack (1988) indicated
that 10 percent of the gray whales showed behavioral changes at that
range.
Response. It is presumed that certain species of marine mammals
outside the 160 dB isopleth will hear the seismic array. For California
waters, Richardson et al. (1991) estimated that airgun sound pulses
would remain above typical ambient noise levels (approximately 75-90
dB) at distances greater than 60 mi (100 km) from the source. However,
as stated previously, being able to hear certain frequency sounds does
not necessarily mean that the marine mammal is being physiologically
stressed by that sound.
Based upon Tyack (1988), who indicates that avoidance behavior
occurs only at relatively close ranges at decibels greater than 120 dB
for continuous noise and 160-170 dB for pulsed sounds such as from
airguns, the marine mammal ZOI for seismic work is considered to be the
160 dB isopleth because seismic arrays are pulsed noise generators
whereas activities such as ATOC result in continuous sound and
therefore has a ZOI set at the 120 dB isopleth. For pulsed sounds such
as airgun arrays, Tyack found that fewer than 10 percent of the animals
located beyond the 160 dB range would show avoidance behavior to the
noise. However, because noise level measurements are logarithmic,
extending the potential ZOI to the 150 dB isopleth, as one commenter
suggests, may unnecessarily impose a larger ZOI. For reference
purposes, it should be noted that ZOI and the terms ``zone of potential
disturbance'' and ``zone of potential harassment'' used in the proposed
authorization, are all considered synonymous.
Comment 6. Two commenters expressed opposing concerns regarding
NMFS' proposed mitigation measure that would require Exxon to leave the
array on if restarting the array would occur during nighttime hours. A
third commenter noted that NMFS' proposed authorization and the Exxon
application differed in that the applicant appeared to envision
monitoring occurring day and night while NMFS envisioned it to occur
only during the day.
Response. One of the mitigation measures proposed by NMFS was for
the airgun arrays to be shut down during turning and maneuvering, and
then be powered up slowly over a 5-minute period. NMFS also proposed
that whenever the array was turned off during nighttime that the array
not be repowered until daylight. As a result of comments, difficulties
with this proposed mitigation measure were identified. If the survey
vessel is not authorized to power up the array during nighttime, the
duration of the survey could be doubled, resulting in increased total
air emissions, fishing preclusion time in the survey area, and costs to
the applicant, although the number of marine mammal incidental
harassments would probably not increase or decrease substantially. In
addition, NMFS has been informed that crew safety concerns will prevent
leaving an array powered up whenever work is needed on the rear deck.
Unfortunately, while leaving at least partial power to one of the
arrays at times when repairs are underway should alert marine mammals
to the presence of the array and prevent potential auditory damage,
this could also result in additional harassments. It is NMFS' view that
ramping up the acoustic array and use of lights to illuminate most of
the 500 ft (152.4 m) safety zone, no serious injury of a marine mammal
should result during nighttime operations. Therefore, NMFS will not
require a mitigation requirement prohibiting turning on an array in
darkness but will modify ramp-up to require the array be linearly
increased by no more than 6 dB/min above 160 dB. This will increase the
ramp-up period from 5 minutes to approximately 15 minutes and will
further ensure that marine mammals can vacate the immediate survey area
if they so choose, prior to potential onset of a temporary threshold
shift injury or less serious harassment.
Comment 7. Two commenters recommended a greater distance between
the vessel and cetaceans prior to turning on and ramping up of the
seismic array. One commenter recommended that the seismic array not be
turned on if marine mammals were within the 160 dB isopleth while the
other commenter noted that within state
[[Page 53758]]
waters mitigation measures prohibit the array from being powered up
whenever cetaceans are within 1.2 nm (2 km) of the survey boat.
Response. While NMFS has established a safety zone for pinnipeds
and odontocetes at 500 ft (152.4 m) and increased the safety zone for
mysticetes to 1,476 ft (450 m), there are several difficulties with
requiring that the seismic device not be turned on if marine mammals
are visible within the 160 dB isopleth. The 160 dB isopleth occurs at a
radius of approximately 2.84 nm (5.2 km) from the seismic source and,
based upon estimates made by NMFS in the proposed authorization,
mysticete/sperm whale harassment incidents are predicted to occur
within this zone. Because harassment takings of mysticetes are
authorized, and harassment takings of odontocetes and pinnipeds are not
expected to occur unless the animals were within the 190 dB isopleth,
termination of the seismic source, if marine mammals are seen within
the 160 dB isopleth, is not warranted. In addition, if Exxon were
required to cease operations each time one of these animals was
sighted, or whenever a pinniped and odontocete was sighted (which
evidence indicates will not be disturbed by seismic array noise in this
area), the survey would result in many data gaps. Depending upon the
frequency of shutting off the array and powering it back up, track
lines could have serious data gaps requiring all or portions of the
track-line to be resurveyed. This would result in increased survey
time.
Because harassment takings only are being authorized by this
action, and because implementing this recommendation is not likely to
result in a lesser impact on marine mammals in the long-term, NMFS does
not believe that it is necessary to require this mitigation measure.
A distance of 1.2 nm (2 km) from the survey vessel, while less
conservative than a 2.84 nm (5.2 km) safety zone, may be unwarranted
and impractical for the same reasons.
In addition, some cetaceans have been reported approaching seismic
survey vessels. If true, this would be evidence that certain species of
marine mammals either do not hear the array or the noise is not
disturbing the animal. NMFS believes that to require this mitigation
measure would impose an unnecessary burden on Exxon, since it would be
required to wait until all marine mammals voluntarily move away from
the area before resuming the survey. Observers however, will be
required to record all marine mammal behavior patterns within the 2.84
nm (5.2 km) ZOI. One purpose of these observations will be to determine
whether pinnipeds and odontocetes react to seismic noise. This
information will then be available for consideration in future seismic
applications.
Comment 8. One commenter recommended that NMFS require Exxon to
implement monitoring methods similar to that used by seismic and oil
development activities in the Beaufort Sea, including an extensive
aerial monitoring program.
Response. While a monitoring protocol based upon monitoring
guidelines recommended for use in the Beaufort Sea will be provided to
Exxon, aerial monitoring is an expensive undertaking whose benefit for
marine mammals must be weighed against the cost of undertaking the
program. In the Beaufort Sea, an extensive monitoring program has been
implemented by MMS since 1979 and MMS and NMFS since 1986, particularly
since 1991, to determine among other things, whether oil and gas
exploration and development activities were having a more than
negligible impact on the availability of bowhead whales for subsistence
purposes during the fall migration of bowheads. More extensive
monitoring requirements were recommended because extensive activities
were conducted (i.e., seismic work, actual drilling, icebreaking
operations and supply ship and aircraft activities) and there were
concerns that such activities might drive bowheads so far offshore that
they would become unavailable for subsistence purposes. Secondary use
of the monitoring program was to determine the level of harassment
takings to bowheads and several other marine mammal species. Aerial
monitoring was augmented by vessel observations, but other mitigation,
such as ramp up and termination of the source whenever a marine mammal
entered a pre-set ZOI was not required as part of the Letter of
Authorization. Because (1) the SYU 160 dB ZOI can be adequately
monitored visually from the bridge of the survey vessel, (2) aerial
marine mammal surveys may result in additional incidental harassment of
marine mammals, (3) mitigation measures imposed will ensure no
harassment takings of pinnipeds and odontocetes nor any TTS injury to
mysticetes will occur, and (4) the relative low abundance of marine
mammals in the Southern California Bight (SCB) during this time of
year, NMFS does not believe that aerial monitoring of the SYU survey
area is warranted solely for monitoring purposes. However, because
aerial surveys can provide valuable information on whale behavior and
can provide a platform for better statistical analyses of behavioral
modification, NMFS recommends that Exxon incorporate an aerial survey
for marine mammals that provides statistically valid results.
Comment 9. Two commenters recommended that the observers on board
the Exxon vessel either be NMFS employees or be an independent third
party contracted by NMFS.
Response. Although NMFS will require Exxon to have an NMFS employee
on board the vessel after December 15th to observe gray whale behavior,
NMFS has neither the staff nor funding to provide observers under small
take authorizations. For this authorization, Exxon has contracted an
independent firm in southern California to provide NMFS-approved
observers. These observers are trained and instructed to record all
observations made on marine mammals (and other sea life), including
times when marine mammals may enter a designated safety zone. NMFS will
require observers to report daily on harassment takes and logbooks be
submitted as part of the reporting requirement. These logbooks will be
reviewed by NMFS and if violations to either the incidental harassment
authorization or the MMPA are found, appropriate action can be taken
under existing procedures.
Comment 10. Several commenters recommended that (a) because sperm
whales and some other species have long dive periods, monitoring
commence sooner than 30 minutes prior to turning on the array, (b) that
monitoring continue 24 hours daily and (c) NMFS and Exxon supplement
the proposed monitoring program with acoustic monitoring capable of
detecting submerged sperm whales and other cetacean species.
Response. NMFS has modified the monitoring program requirements to
make clear that monitoring will be continuous during daylight hours to
(a) ensure that no marine mammals enter the safety zones while the
array is at or above 160 dB, and (b) commence monitoring 30 minutes
prior to the estimated time that the array will reach the 160 dB SPL.
As the ramp-up period has been increased to approximately 15 minutes,
this will mean a minimum monitoring period of 45 minutes. To ensure
adequate monitoring of the safety zone, Exxon will be required, as part
of the authorization, to provide Big Eye binoculars for use by the
observers.
During nighttime hours, monitoring by the observer needs to be
conducted only whenever the array is being powered up. To facilitate
observations
[[Page 53759]]
within the expanded safety zones, Exxon will provide observers with
night-vision binoculars. The 500-ft (91.5 m) safety zone around the
array will be required to be visually monitored by the biological
observer for a minimum of 30 minutes prior to reaching the 160 dB SPL
during ramp up to ensure that no marine mammals are within the zone.
After careful consideration, additional visual monitoring by the
observer during nighttime is viewed as being neither necessary nor
practical, since, as mentioned previously, it is very unlikely that a
marine mammal will enter the safety zone(s) and ramping up will allow
affected marine mammals adequate time to leave the area. Use of
statistical analyses will allow for an estimate of those mysticetes
that may enter the 160-dB ZOI during nighttime. However, a crew member
will be assigned to monitor the area with instructions to alert the
watch stander to the presence of marine mammals and, if necessary,
power-down the source to below 160 dB. The biological observer on call
for such an event will then be promptly notified.
Because the seismic array is broadband in the same frequencies
utilized by the mysticete cetacean species, it is difficult to make
continuous acoustic recordings of mysticete vocalizations and to
distinguish marine mammal vocalizations from other noises. However,
although recordings can be made independent of the survey vessel's
hydrophone array during periods between transmission cycles or while
turning or maneuvering, because (1) there is an authorization to
incidentally harass mysticete whales; (2) the 160 dB ZOI and the 180
and 190 dB safety zones can be adequately monitored visually from the
bridge of the survey vessel because of the small areas involved; (3)
mitigation measures (including ramp up and termination of the source
whenever marine mammals are sighted within their safety zones) imposed
will virtually eliminate any harassment takings of pinnipeds and
odontocetes and any TTS injury to mysticetes, and (4) the relative low
abundance of marine mammals in the SCB during this time of year
especially deep diving sperm whales, NMFS does not believe that a
sophisticated acoustic monitoring of the SYU survey area is warranted
solely for monitoring purposes. However, because acoustic monitoring
can provide valuable information on whale behavior (at least acoustic)
and an indication of behavioral modification with and without seismic
noise, NMFS recommends that Exxon incorporate an acoustical measurement
program for marine mammals.
National Environmental Policy Act Concerns
Comment 11. Two commenters were concerned that there did not appear
to be a recognition of National Environmental Policy Act (NEPA)
responsibilities since it was not mentioned in the proposed
authorization.
Response. The responsibility for reviewing an activity under NEPA
belongs primarily to the responsible Federal agency, if that activity
is Federal, federally-funded, or federally-permitted. The MMS of the
U.S. Department of the Interior has published several documents under
NEPA regarding offshore oil and gas leasing and development in the SYU.
A list of MMS' NEPA references is available upon request (see
ADDRESSES). In addition, an EA on conducting the 3-D seismic survey in
the SYU has recently been released by, and is available from, MMS (see
ADDRESSES). That document, which has been reviewed and adopted in part
(marine mammals) by NMFS, supports NMFS' conclusion that this activity
will have a negligible impact on marine mammal stocks and their
habitat. An analysis of concerns regarding oil spills and other
environmental issues can be found in those documents.
In addition, it should be noted that while each proposed incidental
harassment authorization is reviewed independently by NMFS to determine
its impact on the human environment, NMFS believes that, because the
finding required for incidental harassment authorizations is that the
taking (limited to harassment) have only a negligible impact on marine
mammals and their habitat, the majority of the authorizations should be
categorically excluded (as defined in 40 CFR 1508.4) from the
preparation of either an environmental impact statement or an EA under
NEPA and section 6.02.c.3(i) of NOAA Administrative Order 216-6 for
Environmental Review Procedures (published August 6, 1991). For Exxon's
application, NMFS conducted a review of the impacts expected from the
issuance of an incidental harassment authorization. NMFS has determined
that there will be no more than a negligible impact on marine mammals
from the issuance of the harassment authorization provided the
mitigation measures required under that authorization are implemented
and, based upon this determination and the portions of the MMS EA
adopted by NMFS, has made a finding of no significant impact.
A programmatic EA on issuing incidental harassment authorizations
under section 101(a)(5)(D) of the MMPA is available for public review
and comment until October 16, 1995 (see ADDRESSES).
Other Concerns
Comment 12. Several commenters recommended NMFS require the
immediate suspension of operations if taking by means other than
harassment occurs as a condition of the authorization.
Response. NMFS concurs with this recommendation and has made the
harassment, injury or death of a marine mammal that is not authorized,
or the serious injury or death of a species for which an authorization
has been issued, to be a violation of the authorization and making the
Incidental Harassment Authorization subject to suspension.
Comment 13. One commenter requested NMFS deny the incidental
harassment authorization because the commenter is opposed to more oil
wells and platforms going into operation, and because the risk of oil
spills is significant.
Response. NMFS would like to clarify that it does not authorize the
activity (i.e., conducting the seismic survey); such authorization is
provided by the MMS and is not within the jurisdiction of the Secretary
of Commerce. Rather, NMFS authorizes the unintentional incidental
harassment of marine mammals in connection with such activities and
prescribes methods of taking and other means of effecting the least
practicable adverse impact on the species and its habitat.
Furthermore, the 3-D seismic survey does not involve any oil
drilling or production activities. The survey merely would provide
additional subsurface data that would enable Exxon to more accurately
assess the oil-bearing strata to more efficiently develop the field
while minimizing the number of wells needed to do so. Geological and
geophysical work to gather seismic data is authorized by Exxon's lease.
The Exxon SYU project underwent considerable environmental analysis
during the implementation of the NEPA process and that analysis
identified mitigation measures that would reduce the risk of oil spills
to the extent feasible. These mitigation measures have been
implemented. Additionally, in complying with recent state and Federal
legislation, Exxon has implemented extensive oil spill contingency
planning requirements that further reduce the risk of oil spills.
[[Page 53760]]
Summary of Mitigation Measures
To minimize potential serious injury to marine mammals and to limit
incidental harassment to the lowest practical level, NMFS will require
Exxon to: (1) Ramp up airguns to operating levels at a rate not to
exceed 6 dB/min. from 160 dB to operating level at the start of
operations or testing, when beginning a new trackline, or any time
after the array is powered down below 160 dB; (2) immediately power
down the array to a level below 160 dB whenever a marine mammal is
observed entering either the 500-ft (152.4 m) safety zone for pinnipeds
and odontocetes or the 1,476 ft (450 m) safety zone for mysticetes; (3)
if marine mammals are observed within these safety zones, powering up
the array above 160 dB must be delayed until all marine mammals are
given the opportunity to leave the safety zone; and (4) ensure that the
seismic survey's acoustical sounds do not impede the southbound
migration of the gray whale. To accomplish this latter mitigation
measure, Exxon will be required to notify NMFS if the survey continues
after December 15, 1995, in order for an NMFS biologist to board an
Exxon vessel to observe gray whale behavior, and to determine if a more
than negligible impact on gray whale migration is occurring. At any
time the NMFS biologist can no longer make a negligible impact
determination for gray whales, Exxon will be required to either
terminate the survey or move to an area of the SYU where a negligible
impact determination can again be made. In addition, no incidental
harassment takings will be authorized after December 31, 1995.
Monitoring
NMFS will require that the holder of the Incidental Harassment
Authorization monitor the impact of seismic activities on the marine
mammal populations within the SYU. Monitoring will be conducted by one
or more NMFS-approved observers during all daylight hours using Big Eye
binoculars and whenever the array is being powered up. At all times,
but specifically during routine nighttime surveys when an observer need
only be on standby, the crew is to be instructed to keep watch for
marine mammals. If any are sighted, the watch-stander is to immediately
notify the NMFS-approved observer. If the marine mammal is within the
safety zone, the acoustic source must be immediately powered down. To
facilitate nighttime sightings within the safety zones, high intensity
lighting will be installed and used to light up these zones.
Visual monitoring will commence a minimum of 30 minutes prior to
the estimated time that the array will reach the 160 dB SPL after being
turned on and/or powered up. Monitoring will consist of noting the
numbers and species of all marine mammals seen within the 2.84 nm (5.2
km) ZOI, their behavior whenever the seismic source is off (speed,
direction, submergence time, respiration etc) and any behavioral
responses or modifications of these indicators due either to the
seismic array or vessel. A report on this monitoring program will be
required to be submitted daily by radio, cellular telephone, or fax to
NMFS and within 90 days of completion of the survey. In addition, NMFS
will require Exxon, as part of the authorization, to undertake
additional observations or measurements, or both, necessary to
determine the acoustic properties of the seismic source and the impacts
of seismic activities on marine mammals. These may include aerial
observations and acoustic recordings of marine mammal vocalizations and
are subject to the approval of NMFS prior to initiating the survey.
Consultation
Under section 7 of the Endangered Species Act (16 U.S.C. 1531 et
seq.), NMFS has completed consultation on the issuance of this
authorization. Based on the best available information, NMFS concludes
that the authorization to harass small numbers of cetaceans from
conducting a 3-D seismic survey in the SYU under section 101(a)(5)(D)
of the MMPA is not likely to jeopardize the continued existence of any
listed species. The short-term impact from conducting these surveys may
result in a temporary modification in behavior of certain listed and
non-listed whale species. While temporary behavioral modifications may
be made by these species of cetaceans to avoid seismic noise, this
behavioral change is expected to have only a negligible impact on the
animals.
Conclusions
Since NMFS is assured that the taking will not result in more than
the incidental harassment (as defined by the MMPA Amendments of 1994)
of small numbers of mysticete cetaceans, sperm whales, and possibly
pygmy sperm whales; would have only a negligible impact on these
cetacean stocks; will not have an unmitigable adverse impact on the
availability of these stocks for subsistence uses; and would result in
the least practicable impact on the stocks, NMFS has determined that
the requirements of section 101(a)(5)(D) have been met and the
authorization can be issued.
For the above reasons, NMFS has issued an incidental harassment
authorization for the period ending December 31, 1995, for a 3-D
seismic survey within the SYU provided the above mentioned monitoring
and reporting requirements are incorporated.
Dated: October 11, 1995.
Patricia A. Montanio,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 95-25722 Filed 10-16-95; 8:45 am]
BILLING CODE 3510-22-P
