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1.
Yazvenko SB McDonald TL Blokhin SA Johnson SR Melton HR Newcomer MW Nielson R Wainwright PW 《Environmental monitoring and assessment》2007,134(1-3):93-106
Exxon Neftegas Limited, as operator of the Sakhalin-1 consortium, is developing oil and gas reserves on the continental shelf
off northeast Sakhalin Island, Russia. DalMorNefteGeofizika (DMNG) on behalf of the Sakhalin-1 consortium conducted a 3-D
seismic survey of the Odoptu license area during 17 August–9 September 2001. A portion of the primary feeding area of the
endangered western gray whale (Eschrichtius robustus) is located in the vicinity of the seismic survey. This paper presents data to assess whether western gray whale bottom feeding
activity, as indicated by visible mud plumes, was affected by seismic operations. The mitigation and monitoring program associated
with the seismic survey included aerial surveys during 19 July–19 November 2001. These aerial surveys documented the local
and regional distribution, abundance, and bottom feeding activity of western gray whales. Data on gray whale feeding activity
before, during and after the seismic survey were collected, with the whales assumed to be feeding on the benthos if mud plumes
were observed on the surface. The data were used to assess the influence of seismic survey and other factors (including environmental)
on feeding activity of western gray whales. A stepwise multiple regression analysis failed to find a statistically significant
effect (α = 0.05) of the seismic survey on frequency of occurrence of mud plumes of western gray whales used as a proxy to evaluate
bottom feeding activity in Piltun feeding area. The regression indicated that transect number (a proxy for water depth, related
to distance from shore) and swell height (a proxy for sea state) were the only variables that had a significant effect on
frequency of whale mud plumes. It is concluded that the 2001 seismic survey had no measurable effect (α = 0.05) on bottom feeding activity of western gray whales off Sakhalin Island.
M.W. Newcomer, deceased 相似文献
2.
The introduction of anthropogenic sounds into the marine environment can impact some marine mammals. Impacts can be greatly
reduced if appropriate mitigation measures and monitoring are implemented. This paper concerns such measures undertaken by
Exxon Neftegas Limited, as operator of the Sakhalin-1 Consortium, during the Odoptu 3-D seismic survey conducted during 17
August–9 September 2001. The key environmental issue was protection of the critically endangered western gray whale (Eschrichtius robustus), which feeds in summer and fall primarily in the Piltun feeding area off northeast Sakhalin Island. Existing mitigation
and monitoring practices for seismic surveys in other jurisdictions were evaluated to identify best practices for reducing
impacts on feeding activity by western gray whales. Two buffer zones were established to protect whales from physical injury
or undue disturbance during feeding. A 1 km buffer protected all whales from exposure to levels of sound energy potentially
capable of producing physical injury. A 4–5 km buffer was established to avoid displacing western gray whales from feeding
areas. Trained Marine Mammal Observers (MMOs) on the seismic ship Nordic Explorer had the authority to shut down the air guns if whales were sighted within these buffers.
Additional mitigation measures were also incorporated: Temporal mitigation was provided by rescheduling the program from June–August
to August–September to avoid interference with spring arrival of migrating gray whales. The survey area was reduced by 19%
to avoid certain waters <20 m deep where feeding whales concentrated and where seismic acquisition was a lower priority. The
number of air guns and total volume of the air guns were reduced by about half (from 28 to 14 air guns and from 3,390 in3 to 1,640 in3) relative to initial plans. “Ramp-up” (=“soft-start”) procedures were implemented.
Monitoring activities were conducted as needed to implement some mitigation measures, and to assess residual impacts. Aerial
and vessel-based surveys determined the distribution of whales before, during and after the seismic survey. Daily aerial reconnaissance
helped verify whale-free areas and select the sequence of seismic lines to be surveyed. A scout vessel with MMOs aboard was
positioned 4 km shoreward of the active seismic vessel to provide better visual coverage of the 4–5 km buffer and to help
define the inshore edge of the 4–5 km buffer. A second scout vessel remained near the seismic vessel. Shore-based observers
determined whale numbers, distribution, and behavior during and after the seismic survey. Acoustic monitoring documented received
sound levels near and in the main whale feeding area.
Statistical analyses of aerial survey data indicated that about 5–10 gray whales moved away from waters near (inshore of)
the seismic survey during seismic operations. They shifted into the core gray whale feeding area farther south, and the proportion
of gray whales observed feeding did not change over the study period.
Five shutdowns of the air guns were invoked for gray whales seen within or near the buffer. A previously unknown gray whale
feeding area (the Offshore feeding area) was discovered south and offshore from the nearshore Piltun feeding area. The Offshore
area has subsequently been shown to be used by feeding gray whales during several years when no anthropogenic activity occurred
near the Piltun feeding area.
Shore-based counts indicated that whales continued to feed inshore of the Odoptu block throughout the seismic survey, with
no significant correlation between gray whale abundance and seismic activity. Average values of most behavioral parameters
were similar to those without seismic surveys. Univariate analysis showed no correlation between seismic sound levels and
any behavioral parameter. Multiple regression analyses indicated that, after allowance for environmental covariates, 5 of
11 behavioral parameters were statistically correlated with estimated seismic survey-related variables; 6 of 11 behavioral
parameters were not statistically correlated with seismic survey-related variables. Behavioral parameters that were correlated
with seismic variables were transient and within the range of variation attributable to environmental effects.
Acoustic monitoring determined that the 4–5 km buffer zone, in conjunction with reduction of the air gun array to 14 guns
and 1,640 in3, was effective in limiting sound exposure. Within the Piltun feeding area, these mitigation measures were designed to insure
that western gray whales were not exposed to received levels exceeding the 163 dB re 1 μPa (rms) threshold.
This was among the most complex and intensive mitigation programs ever conducted for any marine mammal. It provided valuable
new information about underwater sounds and gray whale responses during a nearshore seismic program that will be useful in
planning future work. Overall, the efforts in 2001 were successful in reducing impacts to levels tolerable by western gray
whales. Research in 2002–2005 suggested no biologically significant or population-level impacts of the 2001 seismic survey.
M. W. Newcomer is deceased. 相似文献
3.
A geophysical seismic survey was conducted in the summer of 2001 off the northeastern coast of Sakhalin Island, Russia. The
area of seismic exploration was immediately adjacent to the Piltun feeding grounds of the endangered western gray whale (Eschrichtius robustus). This study investigates relative abundance, behavior, and movement patterns of gray whales in relation to occurrence and
proximity to the seismic survey by employing scan sampling, focal follow, and theodolite tracking methodologies. These data
were analyzed in relation to temporal, environmental, and seismic related variables to evaluate potential disturbance reactions
of gray whales to the seismic survey. The relative numbers of whales and pods recorded from five shore-based stations were
not significantly different during periods when seismic surveys were occurring compared to periods when no seismic surveys
were occurring and to the post-seismic period. Univariate analyses indicated no significant statistical correlation between
seismic survey variables and any of the eleven movement and behavior variables. Multiple regression analyses indicated that,
after accounting for temporal and environmental variables, 6 of 11 movement and behavior variables (linearity, acceleration,
mean direction, blows per surfacing, and surface-dive blow rate) were not significantly associated with seismic survey variables,
and 5 of 11 variables (leg speed, reorientation rate, distance-from-shore, blow interval, and dive time) were significantly
associated with seismic survey variables. In summary, after accounting for environmental variables, no correlation was found
between seismic survey variables and the linearity of whale movements, changes in whale swimming speed between theodolite
fixes, mean direction of whale movement, mean number of whale exhalations per minute at the surface, mean time at the surface,
and mean number of exhalations per minute during a whales surface-to-dive cycle. In contrast, at higher received sound energy
exposure levels, whales traveled faster, changed directions of movement less, were recorded further from shore, and stayed
under water longer between respirations. 相似文献
4.
Rutenko AN Borisov SV Gritsenko AV Jenkerson MR 《Environmental monitoring and assessment》2007,134(1-3):21-44
A 3D marine seismic survey of the Odoptu license area off northeastern Sakhalin Island, Russia, was conducted by DalMorNefteGeofizika
(DMNG) on behalf of Exxon Neftegas Limited and the Sakhalin-1 consortium during mid-August through early September 2001. The
key environmental issue identified in an environmental impact assessment was protection of the critically endangered western
gray whale (Eschrichtius robustus), which spends the summer–fall open water period feeding off northeast Sakhalin Island in close proximity to the seismic
survey area. Seismic mitigation and monitoring guidelines and recommendations were developed and implemented to reduce impacts
on the feeding activity of western gray whales. Results of the acoustic monitoring program indicated that the noise monitoring
and mitigation program was successful in reducing exposure of feeding western gray whales to seismic noise. 相似文献