|
Revised polar bear stocks out for review US Fish & Wildlife says Southern Beaufort Sea, Chukchi-Bering Sea populations strategic — declining or likely to be declining Kristen Nelson Petroleum News
The U.S. Fish and Wildlife Service has issued revised population estimates for two stocks of Alaska polar bears, with comments due on the draft revised marine mammal stock assessment reports Sept. 10.
The polar bear, including the Southern Beaufort Sea and Chukchi Sea stocks, was designated as threatened under the Endangered Species Act in May 2008.
The Southern Beaufort Sea polar bear and Chukchi-Bering seas polar bear are strategic stocks — declining or likely to be declining; or currently listed or likely to be listed in the foreseeable future as threatened or endangered under the Endangered Species Act.
Fish and Wildlife regulates taking, possession, transportation, purchasing, selling, offering for sale, exporting and importing of marine mammals under the Marine Mammal Protection Act and it said June 18 that stock assessments are updated periodically to reflect the most current information.
It has been difficult to obtain accurate population estimates for Alaska polar bears “because of low population densities, inaccessibility of the habitat, movement of bears across international boundaries and budget limitations,” the department said.
The most recent population estimate, in 2006, was 1,526 bears for the area from Point Barrow east to the Baillie Islands in Canada.
The department said that when Alaska’s polar bears were hunted primarily by Natives the population was probably at near carrying capacity. Hunting by non-Natives in the early 1960s reduced stocks substantially, but since passage of the Marine Mammal Protection Act in 1972, stocks have increased. The act banned hunting of polar bears, with an exception for Alaska Natives living in coastal communities who are allowed to hunt bears for subsistence and making of handicrafts, “provided that the hunt was not done in a wasteful manner.”
The Southern Beaufort Sea stock experienced little or no growth in the 1990s, the department said, and low growth rates in years of reduced sea ice in 2004 and 2005. An overall declining growth rate of 3 percent from 2001-05 “indicates that the Southern Beaufort Sea population is now declining,” the department said.
The department’s estimate of a minimum population for the stock is 1,397 for the population size of 1,526, for the area from Point Barrow to the Baillie Islands, which results in a calculated potential biological removal of 22 bears per year in order for the stock to remain above its optimum sustainable population, defined as “the number of animals which will result in the maximum productivity of the population or the species, keeping in mind the carrying capacity of the habitat and the health of the ecosystem of which they form a constituent element.”
Stock depleted, threatened The annual harvest from the Southern Beaufort Sea polar bear stock was 39 a year in the 1980s, 33 a year in the 1990s and 32 a year in the 2000s, with an average harvest of 33 in 2003-07. The Canadian harvest for the Southern Beaufort Sea was 21 in the same period, for an average annual Alaska and Canadian harvest during the past five years of 53.6 bears.
The Southern Beaufort Sea polar bear stock is classified as depleted under the Marine Mammal Protection Act and is listed as threatened under the U.S. Endangered Species Act.
“The primary concerns for this population is loss of the sea ice habitat due in part to climate changes in the Arctic, potential overharvest and current and proposed human activities including industrial activities occurring in the near-shore and offshore environment,” the department said.
Data suggests this population is declining and because it is classified as a threatened species it is designated as a strategic stock.
Oil and gas concern Oil and gas exploration is a habitat concern for the Southern Beaufort Sea polar population, the department said, citing a 2004 Minerals Management Service estimate of an 11 percent chance of a marine spill greater than 1,000 barrels in the Beaufort Sea from multiple planned sales.
With a hypothetical 5,912 barrel oil spill from the Northstar offshore oil production facility in the Beaufort Sea, MMS found a low probability that a large number of bears, 25 to 60, might be affected for such a spill and for the purposes of that scenario it was assumed that a polar bear would die if it came into contact with the oil. The range in potential bear deaths was zero to 27 during open water conditions in September and from zero to 74 in mixed ice conditions in October.
At the time of that analysis, based on a stable population size of 1,800 bears, the sustainable average harvest was estimated at 81.1 bears. The department said the actual harvest was 58.2 bears at that time, so an additional 23 bears could have been removed from the population without affecting population levels.
“However, the harvest figure of 81 bears may no longer be sustainable for the Southern Beaufort Sea population so, given the average harvest rate cited above, fewer than 23 oil spill-related mortalities could result in a population decline or increase the time required for recovery,” the department said.
No recent O&G lethal takes During the past five years one Southern Beaufort Sea bear died as a result of research mortality and two bears were euthanized, the department said, but there were no lethal takes of polar bears in oil and gas activities under “incidental take” regulations in the past three years.
1990 is the most recent of three documented lethal takes of polar bears related to oil and gas activities in the Southern Beaufort Sea. The department said one lethal take occurred in 1968 at an offshore drilling site in the Canadian Beaufort Sea; one in 1990 at the Stinson site in the Alaska Beaufort Sea; and one in 1988 when a bear ingested ethylene glycol stored at an offshore island in the Alaska Beaufort.
The department said a polar bear was killed in 1993 at the Oliktok remote radar defense site when it broke into a residence and severely mauled a worked.
Chukchi-Bering seas stock Fish and Wildlife said the Chukchi-Bering seas polar bear population is widely distributed on the pack ice in the Chukchi Sea and northern Bering Sea and adjacent coastal areas in Alaska and Russia, with the northeastern boundary of this stock near the Colville Delta in the central Beaufort Sea and the western boundary near Chauniskaya Bay in the Eastern Siberian Sea; the southern boundary is determined by the annual extent of pack ice.
While the Chukchi-Bering seas population is estimated at some 2,000 animals, the department said a reliable population estimate has been difficult to obtain because of “the vast and inaccessible nature of the habitat, movement of bears across international boundaries, logistical constraints of conducting studies in Russian territory and budget limitations.”
Until 1992 the Chukchi-Bering stock likely “mimicked the growth pattern and later stability of Southern Beaufort Sea stock, since both stocks experienced similar management and harvest histories,” the department said, but since 1992 the Chukchi-Bering stock faced increased harvest in Russia and greater loss of summer sea ice habitat and the population is believed to be declining.
Harvest from the Chukchi-Bering stock was 92 a year in the 1980s, 49 a year in the 1990s and 43 a year in the 2000s, with an annual Alaska harvest from 2003-07 of 37.
Illegal harvest in Russia While Russia prohibited hunting of all polar bears in 1956, problem bears are killed and there has been increased illegal harvest in Russia beginning in 1992, with estimates of annual harvests in Russia as high as 150-250 a year, for a combined Russia-Alaska harvest of some 200 bears in many years.
The department said illegal harvest has not been detected in Alaska and while oil and gas exploration in the Bering-Chukchi region of Alaska began again in 2006, it was primarily in the open water season and has “resulted in minimal interaction with polar bears; there was no evidence of mortality or serious injury.”
The ongoing harvest in western Alaska and Chukotka — the autonomous Russian okrug on the Chukchi Peninsula — “is a concern,” the department said.
“The primary concerns for this population are habitat loss resulting from climate change, potential over-harvest, human activities including industrial activities occurring within the near-shore environment, and potential effects of contaminants on nutritionally stressed populations.”
The department said the stock is designated as a strategic stock because the population is listed as threatened under the Endangered Species Act.
| 