[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)                                          
----------------------------------------------------------------------------------------------------------------
         Sound level                    20LogR                      17LogR                      15LogR          
----------------------------------------------------------------------------------------------------------------
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              
----------------------------------------------------------------------------------------------------------------

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