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Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
Authorization shall 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 (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such taking are set forth.
NMFS has defined “negligible impact” in 50 CFR 216.103 as “* * * an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.”
Section 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the U.S. can apply for an authorization to incidentally take small numbers of marine mammals by harassment. Except with respect to certain activities not pertinent here, the MMPA defines “harassment” as: any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild [Level A harassment]; or (ii) 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 [Level B harassment].
Section 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 marine mammals. Within 45 days of the close of the comment period, NMFS must either issue or deny issuance of the authorization.
NMFS received an application on March 1, 2012, from ION for the taking, by harassment, of marine mammals incidental to a marine seismic survey in ice in the Beaufort and Chukchi Seas, Alaska, during October through December 15, 2012. After addressing comments from NMFS, ION modified its application and submitted a revised application on June 11, 2012.
ION's activities consist of a geophysical in-ice (seismic reflection/refraction) survey and related vessel operations to be conducted primarily in the Alaskan Beaufort and Chukchi seas from October to December 15, 2012. The primary survey area extends from the U.S.-Canadian border in the east to Point Barrow in the west. Two survey lines extend west of Point Barrow into the northern Chukchi Sea, and three short tracks are proposed near the U.S.-Russian border (see Figure 1 of ION's IHA application). The bathymetry of the proposed survey area ranges from shallow (<20 m [66 ft]) to relatively deep (>3,500 m [11,483 ft]) water over the continental shelf, the continental slope, and the abyssal plain.
The survey will be conducted from the seismic vessel
The survey vessels arrived in the survey area from Canadian waters in early October and plan to begin data collection on or after October 15, 2012. After completion of the survey, or when ice and weather conditions dictate, the vessels will exit to the south, transiting through the Chukchi and Bering Seas. The
ION's geophysical survey has been designed and scheduled to minimize potential effects to marine mammals, bowhead whales in particular, and subsistence users. For mitigation and operational reasons, the survey area has been bisected by a line that runs from 70.5° N. 150.5° W. to 73° N. 148° W. (see Figure 1 of ION's IHA application). Weather and ice permitting, ION plans to begin survey operations east of the line described above (eastern survey area) and in offshore waters (>1,000 m [3,281 ft]) where bowheads are expected to be least abundant in early October. This operational plan is based on the fact that only ∼2% of bowhead whales observed by Bureau of Ocean Energy Management's (BOEM) aerial surveys from 1979-2007 occurred in areas of water depth >1,000 m (3,281 ft) (MMS, 2010), and on average ∼97% of bowheads have passed through the eastern U.S. Beaufort Sea by October 15 (Miller
Ice conditions are expected to range from open water to 10/10 ice cover. However, the survey cannot take place in thick multi-year ice as both the icebreaker and seismic vessel must make continuous forward progress at 3-4 kts. In order for the survey to proceed, areas of high ice concentration can only consist of mostly newly forming juvenile first year ice or young first year ice less than 0.5 m (1.6 ft) thick. Sounds generated by the icebreaker and seismic vessel moving through these relatively light ice conditions are expected to be far below the high sound levels often attributed to icebreaking. These high sound levels (>200 dB re 1 μPa [rms]) have been recorded from icebreakers during backing and ramming operations in very heavy ice conditions and are created by cavitation of the propellers as the vessel is slowed by the ice or reverses direction (Erbe and Farmer, 1998; Roth and Schmidt, 2010).
The seismic source used during the project would be an airgun array consisting of 28 Sercel G-gun airguns, of which 26 would be active and have a total discharge volume of 4,450 in
Both vessels will operate industry standard echo sounder/fathometer instruments for continuous measurements of water depth while underway. These instruments are used by all large vessels to provide routine water depth information to the vessel crew. Navigation echo sounders send a single, narrowly focused, high frequency acoustic signal directly downward to the sea floor. The sound energy reflected off the sea floor returns to the vessel where it is detected by the instrument, and the depth is calculated and displayed to the user. Source levels of navigational echo sounders of this type are typically in the 180-200 dB re 1 μPA-m (Richardson
The proposed geophysical survey would be conducted for ∼76 days from approximately October 15 to December 15, 2012. Both the
A notice of NMFS' proposal to issue an IHA to ION was published in the
Any comments specific to ION's application that address the statutory and regulatory requirements or findings NMFS must make to issue an IHA are addressed in this section of the
As described here and in previous FR notices, PTS is considered to be injury (Level A Harassment). However, an animal would need to stay very close to the sound source for an extended amount of time to incur a serious degree of PTS, which could increase the probability of mortality. In this case, it would be highly unlikely for this scenario to unfold given the nature of any anticipated acoustic exposures that could potentially result from a mobile marine mammal that is generally expected to avoid loud sounds swimming in the vicinity of an airgun array moving at 3-4 knots. Therefore, it is appropriate to issue an incidental take authorization under 101(a)(5)(D), as we have made the necessary findings (described elsewhere in this document) under that Section of the MMPA.
As discussed in detail in the Negligible Impact and Small Numbers Analysis and Determination section of this document, most of the takes from ION's proposed in-ice seismic surveys are expected to be Level B behavioral harassment, in the form of startle behavior or vacating the area for the short duration of time when the seismic airgun is firing in the area. Animals could also change their behavior patterns during this short duration, butare expected to resume their normal activities and reoccupy the area as soon as the vessels move away. Additionally, since the proposed icebreaking seismic survey is planned outside the time when ice seals are giving birth and after approximately 97% of the bowhead population is expected to have moved through the area, no impacts on pups or calves are expected, and nor are there any orther areas of particular importance for reproduction or feeding that could be impacted. Therefore, any behavioral effects to ringed seals, bowheads, or other species are not expected to have significant impacts to individual fitness or the population. In addition, the mitigation and monitoring measures (described previously in this document) included in the IHA are expected to further reduce any potential disturbance to marine mammals. Last, a small number of takes in the form of PTS are being authorized, however, if incurred, they would be expected to be minor in degree (low intensity—a few dBs of loss at certain frequencies), and they are not expected because of a combination of mitigation and likely avoidance of high source levels. Mortality is neither authorized nor anticipated.
Therefore, NMFS believes that the take, by harassment, from ION's in-ice seismic survey will have a negligible impacton the affected species or stocks.
In addition, cumulative effects were addressed in the Environmental Assessment and biological opinion prepared for this action, both of which NMFS indicated would be completed prior to the issuance of an IHA (77 FR 49922; August 17, 2012). The Environmental Assessment's cumulative effects analysis included consideration of (among other things): BP Exploration (Alasks), Inc.'s (BPXA) ocean-bottom-cable seismic surveys in the Simpson Lagoon area of the Beaufort Sea; BPXA's proposed Northstar oil production activity in the Beaufort Sea; and Shell Offshore Inc.'s (Shell) proposed exploratory drilling activities in the Beaufort and Chukchi Seas, Arctic warming, subsistence hunting, and noise contribution from vessel traffic.
These documents, as well as the Alaska Marine Stock Assessments and the most recent abundance estimates for the affected species, are part of NMFS' Administrative Record for this action, and provided the decision maker with information regarding other activities in the action area that affect marine mammals, an analysis of cumulative impacts, and other information relevant to the determination made under the MMPA.
Regarding the environmental baseline, as described in the
Separately, regarding marine mammal responses to noise in general and as described in the
Finally, we acknowledge that bowhead and gray whales may remain in the Beaufort and Chukchi Seas during the timeframe of ION's proposed survey. To account for this possibility, NMFS relied on summer/fall data to estimate potential abundance of these species, which resulted in an over-estimate of take.
If the percentage decrease were left unrounded the average density for water depths <200 m in the Eastern Beaufort Sea in Table 2 of the ION's IHA application would become 0.0132 bowheads/km
NMFS and ION by focused on bowhead whale aerial surveys that were conducted in the spring of 2011 and 2012. We ultimately agreed that the aerial survey data being used for density calculations was the most appropriate and that any newer data (
The determination regarding whether the total taking would have a negligible impact on the species or stocks is based on the species-specific average density, or based on allotted number from past chance occurrence, as described above and in the proposed
Regarding the requirement for ION to account for all sources of uncertainty in its estimation approach, including animals that may be present but not observed, NMFS believes that all population survey studies, as well as density estimates, take into account for marine mammals not observed during the survey.
Noise-induced threshold shifts (TS, include PTS) are defined as increases in the threshold of audibility (
In addition, there are different degrees of PTS: Ranging from slight/mild to moderate and from severe to profound (Clark 1981). Profound PTS or the complete loss of the ability to hear in one or both ears is commonly referred to as deafness (CDC 2004; WHO 2006). High-frequency PTS, presumably as a normal process of aging that occurs in humans and other terrestrial mammals, has also been demonstrated in captive cetaceans (Ridgway and Carder 1997; Yuen
In terms of what is analyzed for the potential PTS (Level A harassment) in marine mammals as a result of ION's in-ice seismic survey, if it occurs, NMFS has determined that the levels would be slight/mild because research shows that most cetaceans (and particularly Arctic cetaceans) show relatively high levels of avoidance when received sound pulse levels exceed 160 dB re 1 μPa (rms) (review in Richardson
In addition, NMFS provided more detailed analyses on noise-induced stress in its EA for the issuance of an IHA to ION (NMFS 2012), which also included three specific studies concerning marine mammals (Thomas
Nevertheless, NMFS recognizes that the TTS threshold of harbor porpoise is lower that other cetacean species (bottlenose dolphin and beluga whale) tested (
As far as the hearing sensitivity of mid-frequency cetaceans is concerned, it is well known that mid-frequency cetaceans have greater sensitivity to sounds within their best hearing ranges, which are typically between 10-100 kHz (Johnson 1967; Hall and Johnson 1972; White
The 10% correction factor used by NMFS is appropriate for estimating likely Level A Harassment takes, since there is evidence suggesting that most, if not all, marine mammals would avoid the noise levels that could cause immediate PTS (as described in the Estimated Take section below.
NMFS does not agree with the Commission's recommendation. Again, there is a difference between potential TTS (Level B Harassment), potential PTS (Level A Harassment) and serious injury. As described in detail in the response to Comment 13, the 180/190 dB re 1 μPa are the current standards used to prevent marine mammals from experiencing injury, which is equated with PTS, not TTS, which occurs at substantively lower received levels than PTS. In fact, all studies on marine mammal TTS have pointed out that TTS occurs at a received levels higher than NMFS current 180/190 dB re 1 μPa threshold (
Finally, even if the animal receives PTS, this does not equate to serious injury. As stated earlier in response to Comment 13, NMFS defines injury as “any injury that will likely result in mortality” (50 CFR 229.2), which, based on the best available science and NMFS' judgment, does not include PTS. .
To address these observations, it is important to understand that the vocal behaviors shown by fin and humpback whales, as reported by Clark and Gagnon (2006) and Risch
Based on the information and data summarized in Southall
Although it has been known that at long distances an impulse acoustic signal will lose its pulse feature by stretching its duration due to multipath propagation, these signals (or noises) are still fundamentally different from other non-impulse noise sources such as those from vibratory pile driving, drilling, and dredging based on the following characteristics:
First, the elongated pulse signals from the airgun array at far distances are caused by multipath propagation in a reverberant environment (Greene and Richardson 1988; Richardson
Second, even though during horizontal propagation, the initial short pulse could be “stretched” from milliseconds when emitted to about 0.25-0.5 second long at a few kilometers in shallow water (Richardson
Therefore, NMFS does not agree that it is appropriate to treat elongated airgun pulses at long distances as a “conventional” non-pulse signal and apply the 120 dB behavioral response threshold to that received sound.