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Roberto Racca - One of the best experts on this subject based on the ideXlab platform.
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monitoring and impact mitigation during a 4d Seismic Survey near a population of gray whales off sakhalin island russia
Endangered Species Research, 2015Co-Authors: Koen Broker, Glenn Gailey, Judy Muir, Roberto RaccaAbstract:A 4D Seismic Survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales’ feeding activity and enhance understanding of the potential impacts of Seismic Surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on Seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa2-s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore- and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales’ position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the Seismic source was implemented. Additionally, behaviour and distribution Surveys were conducted before, during and after the Seismic Survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the Seismic Survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to Seismic sounds. KEY WORDS: Seismic · Mitigation · Western gray whale · Eschrichtius robustus · Sakhalin · Piltun · Sea of Okhotsk · Anthropogenic disturbance
Glenn Gailey - One of the best experts on this subject based on the ideXlab platform.
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monitoring and impact mitigation during a 4d Seismic Survey near a population of gray whales off sakhalin island russia
Endangered Species Research, 2015Co-Authors: Koen Broker, Glenn Gailey, Judy Muir, Roberto RaccaAbstract:A 4D Seismic Survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales’ feeding activity and enhance understanding of the potential impacts of Seismic Surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on Seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa2-s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore- and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales’ position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the Seismic source was implemented. Additionally, behaviour and distribution Surveys were conducted before, during and after the Seismic Survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the Seismic Survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to Seismic sounds. KEY WORDS: Seismic · Mitigation · Western gray whale · Eschrichtius robustus · Sakhalin · Piltun · Sea of Okhotsk · Anthropogenic disturbance
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a western gray whale mitigation and monitoring program for a 3 d Seismic Survey sakhalin island russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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’ 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’ 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’ km buffer and to help define the inshore edge of the 4’ 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 5’0 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’ 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 2002’005 suggested no biologically significant or population-level impacts of the 2001 Seismic Survey.
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Abundance, behavior, and movement patterns of western gray whales in relation to a 3-D Seismic Survey, Northeast Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: Glenn Gailey, Bernd Würsig, Trent L McdonaldAbstract: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.
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A western gray whale mitigation and monitoring program for a 3-D Seismic Survey, Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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
Koen Broker - One of the best experts on this subject based on the ideXlab platform.
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monitoring and impact mitigation during a 4d Seismic Survey near a population of gray whales off sakhalin island russia
Endangered Species Research, 2015Co-Authors: Koen Broker, Glenn Gailey, Judy Muir, Roberto RaccaAbstract:A 4D Seismic Survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales’ feeding activity and enhance understanding of the potential impacts of Seismic Surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on Seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa2-s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore- and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales’ position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the Seismic source was implemented. Additionally, behaviour and distribution Surveys were conducted before, during and after the Seismic Survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the Seismic Survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to Seismic sounds. KEY WORDS: Seismic · Mitigation · Western gray whale · Eschrichtius robustus · Sakhalin · Piltun · Sea of Okhotsk · Anthropogenic disturbance
S.r. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Distribution and abundance of western gray whales during a Seismic Survey near Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: S. B. Yazvenko, S. K. Meier, H. R. Melton, M. W. Newcomer, Trent L Mcdonald, S. A. Blokhin, S.r. Johnson, R. M. Nielson, V. L. Vladimirov, P. W. WainwrightAbstract:Exxon Neftegas Limited, 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-September 2001. A portion of the primary known feeding area of the endangered western gray whale ( Eschrichtius robustus ) is located adjacent to the Seismic block. The data presented here were collected as part of daily monitoring to determine if there was any measurable effect of the Seismic Survey on the distribution and abundance of western gray whales. Mitigation and monitoring program included aerial Surveys conducted between 19 July and 19 November using the methodology outlined by the Southern California High Energy Seismic Survey team (HESS). These Surveys provided documentation of the distribution, abundance and bottom feeding activity of western gray whales in relation to Seismic Survey sounds. From an operations perspective, the aerial Surveys provided near real-time data on the location of whales in and outside the feeding area, and documented whether whales were displaced out of an area normally used as feeding habitat. The objectives of this study were to assess (a) temporal changes in the distribution and abundance of gray whales in relation to Seismic Survey, and (b) the influence of Seismic Survey, environmental factors, and other variables on the distribution and abundance of gray whales within their preferred feeding area adjacent to Piltun Bay. Multiple regression analysis revealed a limited redistribution of gray whales southward within the Piltun feeding area when the Seismic Survey was fully operational. A total of five environmental and other variables unrelated to Seismic Survey (date and proxies of depth, sea state and visibility) and one Seismic Survey-related variable ( seg3d , i.e., received sound energy accumulated over 3 days) had statistically significant effects on the distribution and abundance of gray whales. The distribution of two to four gray whales observed on the surface (i.e., about five to ten whales in total) has likely been affected by the Seismic Survey. However, the total number of gray whales observed within the Piltun feeding area remained stable during the Seismic Survey.
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Feeding of western gray whales during a Seismic Survey near Sakhalin Island, Russia.
Environmental monitoring and assessment, 2007Co-Authors: S. B. Yazvenko, H. R. Melton, M. W. Newcomer, Trent L Mcdonald, S. A. Blokhin, S.r. Johnson, R Nielson, P. W. WainwrightAbstract: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 (alpha = 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 (alpha = 0.05) on bottom feeding activity of western gray whales off Sakhalin Island.
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a western gray whale mitigation and monitoring program for a 3 d Seismic Survey sakhalin island russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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’ 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’ 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’ km buffer and to help define the inshore edge of the 4’ 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 5’0 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’ 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 2002’005 suggested no biologically significant or population-level impacts of the 2001 Seismic Survey.
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A western gray whale mitigation and monitoring program for a 3-D Seismic Survey, Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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
S. B. Yazvenko - One of the best experts on this subject based on the ideXlab platform.
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Distribution and abundance of western gray whales during a Seismic Survey near Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: S. B. Yazvenko, S. K. Meier, H. R. Melton, M. W. Newcomer, Trent L Mcdonald, S. A. Blokhin, S.r. Johnson, R. M. Nielson, V. L. Vladimirov, P. W. WainwrightAbstract:Exxon Neftegas Limited, 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-September 2001. A portion of the primary known feeding area of the endangered western gray whale ( Eschrichtius robustus ) is located adjacent to the Seismic block. The data presented here were collected as part of daily monitoring to determine if there was any measurable effect of the Seismic Survey on the distribution and abundance of western gray whales. Mitigation and monitoring program included aerial Surveys conducted between 19 July and 19 November using the methodology outlined by the Southern California High Energy Seismic Survey team (HESS). These Surveys provided documentation of the distribution, abundance and bottom feeding activity of western gray whales in relation to Seismic Survey sounds. From an operations perspective, the aerial Surveys provided near real-time data on the location of whales in and outside the feeding area, and documented whether whales were displaced out of an area normally used as feeding habitat. The objectives of this study were to assess (a) temporal changes in the distribution and abundance of gray whales in relation to Seismic Survey, and (b) the influence of Seismic Survey, environmental factors, and other variables on the distribution and abundance of gray whales within their preferred feeding area adjacent to Piltun Bay. Multiple regression analysis revealed a limited redistribution of gray whales southward within the Piltun feeding area when the Seismic Survey was fully operational. A total of five environmental and other variables unrelated to Seismic Survey (date and proxies of depth, sea state and visibility) and one Seismic Survey-related variable ( seg3d , i.e., received sound energy accumulated over 3 days) had statistically significant effects on the distribution and abundance of gray whales. The distribution of two to four gray whales observed on the surface (i.e., about five to ten whales in total) has likely been affected by the Seismic Survey. However, the total number of gray whales observed within the Piltun feeding area remained stable during the Seismic Survey.
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Feeding of western gray whales during a Seismic Survey near Sakhalin Island, Russia.
Environmental monitoring and assessment, 2007Co-Authors: S. B. Yazvenko, H. R. Melton, M. W. Newcomer, Trent L Mcdonald, S. A. Blokhin, S.r. Johnson, R Nielson, P. W. WainwrightAbstract: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 (alpha = 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 (alpha = 0.05) on bottom feeding activity of western gray whales off Sakhalin Island.
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a western gray whale mitigation and monitoring program for a 3 d Seismic Survey sakhalin island russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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’ 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’ 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’ km buffer and to help define the inshore edge of the 4’ 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 5’0 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’ 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 2002’005 suggested no biologically significant or population-level impacts of the 2001 Seismic Survey.
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A western gray whale mitigation and monitoring program for a 3-D Seismic Survey, Sakhalin Island, Russia
Environmental Monitoring and Assessment, 2007Co-Authors: S.r. Johnson, S. B. Yazvenko, M. R. Jenkerson, S. K. Meier, H. R. Melton, M. W. Newcomer, S. A. Blokhin, W J Richardson, Glenn Gailey, A. S. PerlovAbstract: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
