Far East Seas, Whales and Oil Drilling
Endangered Sakhalin gray whales face cumulative threats on their feeding ground during summer 2001
Robert L. Brownell. Jr. (1) and Alexey V. Yablokov (2)
(1) Southwest Fisheries Science Center, La Jolla, California, USA
(2) Center for Russian Environmental Policy, Moscow, Russia
The endangered western gray whale population, now believed to number less than 100, summers and feeds off the northeastern coast of Sakhalin Island (Weller et al. 1999, 2001). Development of major offshore oil and gas fields, within near proximity of where these gray whales feed, are ongoing and oil production started in 1999. Since the mid 1990s, whales feeding off Sakhalin Island have had to coexist with high intensity seismic exploration, placement of temporary drilling rigs, increased ship and helicopter traffic, and the installation of a major drilling and production platform; all within 10-20 km of their primary feeding habitat. Concerns about this development include threats of an oil spill to the whales and/or their food, and disruption to the whales by underwater noise from seismic surveys, drilling and production rigs, and associated support vessels and helicopters operating in the areas around the Sakhalin I and Sakhalin II projects (Brownell et al. 1997).
This note reviews additional threats that these whales will be facing during the summer of 2001, when intensive geophysical seismic surveys will be conducted near the feeding grounds.
Proposed Seismic Surveys
Major oil and gas fields occur off the northeastern shore of Sakhalin Island (Fig. 1). The two active projects in this area are called Sakhalin I (Exxon) and Sakhalin II (SEIC). They are located offshore the summer feeding ground of the western gray whales (Fig. 1). Seismic surveys and exploration wells are used to find specific oil and gas deposits within the leases operated by each company. This type of work started in the mid 1990's and has proceeded at a rapid pace. The Sakhalin II project started oil production in1999.
During summer 2001, the Sakhalin I project will conduct additional seismic surveys in an area very near where the gray whales will be feeding. The exact timing of these surveys is unknown, but operations will probably start in early August 2001 and continue for three or four weeks. Peak numbers of whales are on the feeding grounds July-September (Weller et al. 1999). Therefore, potential impacts from exposure to seismic noise may affect all animals in the area (even those 30 km or more from the seismic array) and possibly the entire population. Mitigation plans to keep disturbance of the gray whales to a minimum have not been make public, and it is unclear why these survey operations were not scheduled prior to the arrival of whales to the feeding grounds after break-up of the winter ice sheet (April - May) or subsequent to their departure (late November -December) but prior to formation of sea ice.
Concerns for Western Gray Whales
The western gray whale population was estimated to include 100 to 250 animals. However, recent evidence suggests that the population is less than 100 whales. The western gray whale is one of the world's most endangered large whale populations. The small number of whales remaining in the population, in combination with the possibility that fewer than 50 reproductive individuals exist, served as the basis for The World Conservation Union (IUCN) listing (his population as Critically Endangered (Hilton-Taylor 2000).
Since the western gray whale was classified as critically endangered by the IUCN, the status of this population has continued to deteriorate. Some of the new concerns include: gray whale products appeared in Japanese commercial markets in 1999 (Baker et al. In press), increase in frequency of "skinny" whales observed on the Sakhalin feeding grounds between 1999 and 2000, unusually low calf survival estimates, apparent 2:1 male bias in the population, and quantitative mark-recapture population size estimates for 1997-2000 indicated < 100 whales exist (Brownell and Weller 2001, Vinogradov 2001, Weller et al. 2001).
The planned seismic survey work this summer on the Odoptu field (Sakhalin I) is slated to occur at the northern half of the primary feeding grounds off Piltun, and should be the cause of grave concern. Gray whales have a reaction threshold to seismic noise similar to that of bowhead whales. Bowheads usually avoid seismic vessels operating within several km.
Studies of bowhead responses to seismic vessels at greater distances have shown avoidance at distances as great as 24 km. In 1997 a U.S.-Russian research team documented apparent behavioral shifts of gray whales off Sakhalin in relation to active seismic ships when they were working > 30 km away (Wursig et al. 1997). Even with a proper whale-monitoring program in place for the 2001 seismic surveys, noise from open-water seismic operations can potentially permeate the entire feeding area and could affect whales many kilometers away from the seismic array. Further, helicopter and support vessel traffic associated with the seismic monitoring and other activities also adds significant potential for disturbing the whales. It is also known that large amounts of drilling materials were observed in the region around the drilling platform (Vinogradov 2001).
Shore-based studies of gray whales between 1997 and 2000 on the Sakhalin feeding grounds indicate that a shift in distribution to the north occurred in 1999 and 2000. Although the causal mechanism for this apparent shift is unexplained, it is reasonable to assume that whales have moved to find food, or to avoid the industry-related activities at the more southern end of the feeding grounds. A majority of the industry-related activities, including the location of the offshore drilling and production platform "Molikpaq" (Sakhalin II), currently taking place on the Sakhalin shelf occur at the southern end of the primary feeding habitat. Thus, if whales moved to the northern portion of the feeding grounds to locate a better prey base, or if they moved to avoid ongoing industry disturbance in the south, conducting seismic work in the north during 2001 may have significant consequences. For example, survey work in the north and current production activities in the south may exclude whales from their preferred feeding area, or essentially "box" whales in at northern and southern ends of their main feeding habitat. It is clear that when an endangered whale population is being threatened a public document of planned monitoring studies and mitigation procedures should be available for public and scientific comment. However, we are unaware of such a document at this time.
The cumulative impacts that seismic operations may have on the health of western gray whales, especially those observed to be "skinny" in 1999 and 2000, should be of significant concern to the oil companies sponsoring the 2001 work. Any skinny whales that return to the Piltun feeding grounds in 2001 will have below normal body fat reserves and will need to feed efficiently for the maximum number of days possible before the winter ice causes them to migrate south. Females that return to the feeding ground with calves or that had a calf early in 2001 will be in the most serious condition regarding depleted fat reserves. Mother-young separations generally occur between July and September (Weller et al. 1999). Feeding is extremely important for these whales as the adult females are still lactating and also need to store lipids for the late fall migration. The young need to suckle as they continue to grow as well as feed on their own before the separation from their mothers in mid to late summer. Therefore, until we better understand the extent to which whales in this population maybe nutritionally and socially compromised, we recommend that no additional seismic surveys take place in this area while whales are on the feeding grounds.
However, if the seismic surveys go forward in the summer of 2001, we are interested in learning the details of the monitoring and mitigation plans developed. We are also curious to know how the health status and behavioral reactions of gray whales (including those quite distant from the seismic ship) will be monitored in relation to such activities. Even more difficult is conducting a suitable monitoring program in an area known for its poor weather. Thus, gray whales will be difficult to monitor without good weather, but good weather is not needed for the scheduled seismic surveys. Anthropogenic threats occur throughout the range of this population and need to be minimized whenever and wherever possible to give these whales the best chance for survival. One relatively simple mitigation strategy in the present situation would be to conduct seismic operations prior to the arrival or subsequent to the departure of whales on the feeding grounds (as is done off the north slop of Alaska for bowhead whales). Special monitoring and planning is needed for projects that have the possibility for cumulative impacts, like oil and gas development in the waters off Sakhalin Island where critically endangered gray whales feed.
Baker, C. S. et al. In press.
Gray whale products sold in commercial markets along the Pacific coast of Japan. Marine Mammal Science.
Brownell, R. L., Jr. and Weller, D. W. 2001.
Is the carrying capacity hypothesis a plausible explanation for the "skinny" gray whale phenomenon? Unpublished IWC document SC/53/BRG 20.
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