Polar Bear in its Natural Habitat
Human Impact on Polar Bears
1.Hunting:
•Polar bears have been hunted for thousands of years.
°Evidence of human polar bear hunts have been found in 2,500 to 3,000 year-old ruins. Arctic peoples have traditionally hunted polar bears for food, clothing, bedding, and religious purposes.
°Commercial hunting of polar bears for hides began as early as the 1500s and flourished by the 1700s.
°Kills increased substantially in the 1950s and 1960s when hunters began using snowmobiles, boats, and airplanes to hunt polar bears. Public concern about these hunting methods led to an international agreement in 1973 banning the use of aircraft or large motorized boats for polar bear hunts.
•For the last several decades, hunting has been the greatest known cause of polar bear mortality.
°Today, polar bears are hunted by native arctic populations primarily for food, clothing, handicrafts, and sale of skins. Polar bears are also killed in defense of people or property.
°Hunting is government-regulated in Canada, Greenland, and the United States. Hunting is currently banned in Norway and parts of Russia.
2.Environmental threats:
•Climate change impacts in the Arctic, including increasing temperatures, shifts in the distribution of multi-year ice, and changes in precipitation patterns, threaten polar bear populations in a number of ways.
°Increasing temperatures are associated with a decrease in sea ice (both the amount and length of time sea ice forms).
°Since polar bears use sea ice as a platform to prey mainly on ringed and bearded seals, changes in sea ice can lead to less access to prey and an increase in malnourished or starving bears.
°Because of their strong association with the ice, ringed seal populations may also plummet due to loss of sea ice and result in even further reduction in polar bear food supplies.
°In addition, with less sea ice, female polar bears may have a more difficult time reaching traditional denning areas.
•Oil spills from drilling platforms or tankers potentially threaten polar bears.
°A polar bear's fur loses its insulating properties when covered with oil.
°Oil spills could diminish or contaminate polar bear food sources.
°Scientists are trying to determine whether noise from industrial subsistence or recreational activities could disturb polar bears and deter them from important habitats.
•The presence of toxic chemicals in polar bears may have long-term effects on their health and longevity.
°Toxic chemicals from worldwide industrial activities are carried to the Arctic by air currents, rivers, and oceans.
°Arctic animals in higher food chain levels concentrate greater amounts of toxic chemicals in their tissues than those below them. Because polar bears are top predators in the arctic, they are exposed to especially high levels of toxic chemicals.°Human-made toxic chemicals such as heavy metals, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and organochlorines are present in the Arctic. Arctic seals have particularly high levels of organochlorines concentrated in their blubber. Since polar bears mainly feed on seals, organochlorines become even more concentrated in the fat layer of polar bears. This potentially leads to a higher than normal mortality rate of polar bear cubs who acquire these toxins from their mother's milk.
°Scientists continue to monitor the levels of toxic chemicals in polar bears to determine their long-term effects.
•Radionuclides, from nuclear waste dumping in the Russian Arctic, may have detrimental effects on polar bears, and the arctic ecosystem as a whole.
•Polar bears have been hunted for thousands of years.
°Evidence of human polar bear hunts have been found in 2,500 to 3,000 year-old ruins. Arctic peoples have traditionally hunted polar bears for food, clothing, bedding, and religious purposes.
°Commercial hunting of polar bears for hides began as early as the 1500s and flourished by the 1700s.
°Kills increased substantially in the 1950s and 1960s when hunters began using snowmobiles, boats, and airplanes to hunt polar bears. Public concern about these hunting methods led to an international agreement in 1973 banning the use of aircraft or large motorized boats for polar bear hunts.
•For the last several decades, hunting has been the greatest known cause of polar bear mortality.
°Today, polar bears are hunted by native arctic populations primarily for food, clothing, handicrafts, and sale of skins. Polar bears are also killed in defense of people or property.
°Hunting is government-regulated in Canada, Greenland, and the United States. Hunting is currently banned in Norway and parts of Russia.
2.Environmental threats:
•Climate change impacts in the Arctic, including increasing temperatures, shifts in the distribution of multi-year ice, and changes in precipitation patterns, threaten polar bear populations in a number of ways.
°Increasing temperatures are associated with a decrease in sea ice (both the amount and length of time sea ice forms).
°Since polar bears use sea ice as a platform to prey mainly on ringed and bearded seals, changes in sea ice can lead to less access to prey and an increase in malnourished or starving bears.
°Because of their strong association with the ice, ringed seal populations may also plummet due to loss of sea ice and result in even further reduction in polar bear food supplies.
°In addition, with less sea ice, female polar bears may have a more difficult time reaching traditional denning areas.
•Oil spills from drilling platforms or tankers potentially threaten polar bears.
°A polar bear's fur loses its insulating properties when covered with oil.
°Oil spills could diminish or contaminate polar bear food sources.
°Scientists are trying to determine whether noise from industrial subsistence or recreational activities could disturb polar bears and deter them from important habitats.
•The presence of toxic chemicals in polar bears may have long-term effects on their health and longevity.
°Toxic chemicals from worldwide industrial activities are carried to the Arctic by air currents, rivers, and oceans.
°Arctic animals in higher food chain levels concentrate greater amounts of toxic chemicals in their tissues than those below them. Because polar bears are top predators in the arctic, they are exposed to especially high levels of toxic chemicals.°Human-made toxic chemicals such as heavy metals, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and organochlorines are present in the Arctic. Arctic seals have particularly high levels of organochlorines concentrated in their blubber. Since polar bears mainly feed on seals, organochlorines become even more concentrated in the fat layer of polar bears. This potentially leads to a higher than normal mortality rate of polar bear cubs who acquire these toxins from their mother's milk.
°Scientists continue to monitor the levels of toxic chemicals in polar bears to determine their long-term effects.
•Radionuclides, from nuclear waste dumping in the Russian Arctic, may have detrimental effects on polar bears, and the arctic ecosystem as a whole.
"POLAR BEARS - Longevity & Causes of Death." POLAR BEARS - Longevity & Causes of Death. Seaworld, n.d. Web. 20 Apr. 2013. <http://www.seaworld.org/animal-info/info-books/polar-bear/longevity.htm>.