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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations
non-mechanical response strategy is the use of chemical dispersants to speed dissipation of oil from the water surface and disperse it within the water column in small droplets. However, dispersant use presents environmental trade-offs.
While walruses and polar bears would likely benefit from reduced surface or shoreline oiling, dispersant use could have negative impacts on the aquatic food chain. Oil spill cleanup in the broken-ice and open-water conditions that characterize Arctic waters is problematic.

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Evaluation of Effects of Oil Spills on Pacific Walruses and Polar Bears The MMPA does not authorize the incidental take of marine mammals as the result of illegal actions, such as oil spills. Nor do the specified activities in AOGAs request include oil spills. Any event that results in an injurious or lethal outcome to a marine mammal is not authorized under this ITR. However, for the purpose of developing a more complete context for evaluating potential effects on walruses and polar bears, the Service evaluated the potential impacts of oil spills within the Beaufort Sea ITR region.
Pacific Walrus As stated earlier, the Beaufort Sea is not within the primary range for walruses. Therefore, the probability of walruses encountering oil or waste products as a result of a spill from Industry activities is low. Onshore oil spills would not impact walruses unless they occurred on or near beaches or oil moved into the offshore environment.
However, in the event of a spill that occurs during the open-water season, oil in the water column could drift offshore and possibly encounter a small number of walruses. Oil spills from offshore platforms could also contact walruses under certain conditions. For example, spilled oil during the ice-covered season that isnt cleaned up could become part of the ice substrate and could eventually be released back into the environment during the following open-water season.
Additionally, during spring melt, oil would be collected by spill response activities, but it could eventually contact a limited number of walruses.
Little is known about the effects of oil, specifically on walruses, as no studies have been conducted to date.
Hypothetically, walruses may react to oil much like other pinnipeds. Walruses are not likely to ingest oil while grooming since walruses have very little hair and exhibit no grooming behavior.
Adult walruses may not be severely affected by the oil spill through direct contact, but they will be extremely
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sensitive to any habitat disturbance by human noise and response activities. In addition, due to the gregarious nature of walruses, an oil spill would most likely affect multiple individuals in the area.
Walruses may also expose themselves more often to the oil that has accumulated at the edge of a contaminated shore or ice lead if they repeatedly enter and exit the water.
Walrus calves are most likely to suffer the ill-effects of oil contamination.
Female walruses with calves are very attentive, and the calf will always stay close to its motherincluding when the female is foraging for food. Walrus calves can swim almost immediately after birth and will often join their mother in the water. It is possible that an oiled calf will be unrecognizable to its mother either by sight or by smell and be abandoned. However, the greater threat may come from an oiled calf that is unable to swim away from the contamination and a devoted mother that would not leave without the calf, resulting in the potential mortality of both animals. Further, a nursing calf might ingest oil if the mother was oiled, also increasing the risk of injury or mortality.
Walruses have thick skin and blubber layers for insulation. Heat loss is regulated by control of peripheral blood flow through the animals skin and blubber. The peripheral blood flow is decreased in cold water and increased at warmer temperatures. Direct exposure of walruses to oil is not believed to have any effect on the insulating capacity of their skin and blubber, although it is unknown if oil could affect their peripheral blood flow.
Damage to the skin of pinnipeds can occur from contact with oil because some of the oil penetrates the skin, causing inflammation and death of some tissue. The dead tissue is discarded, leaving behind an ulcer. While these skin lesions have only rarely been found on oiled seals, the effects on walruses may be greater because of a lack of hair to protect the skin. Direct exposure to oil can also result in conjunctivitis. Like other pinnipeds, walruses are susceptible to oil contamination in their eyes. Continuous exposure to oil will quickly cause permanent eye damage.
Inhalation of hydrocarbon fumes presents another threat to marine mammals. In studies conducted on pinnipeds, pulmonary hemorrhage, inflammation, congestion, and nerve damage resulted after exposure to concentrated hydrocarbon fumes for a period of 24 hours. If the walruses were also under stress from molting, pregnancy, etc., the increased heart rate associated with the stress would
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circulate the hydrocarbons more quickly, lowering the tolerance threshold for ingestion or inhalation.
Walruses are benthic feeders, and much of the benthic prey contaminated by an oil spill would be killed immediately. Others that survived would become contaminated from oil in bottom sediments, possibly resulting in slower growth and a decrease in reproduction. Bivalve mollusks, a favorite prey species of the walrus, are not effective at processing hydrocarbon compounds, resulting in highly concentrated accumulations and longterm retention of the contamination within the organism. Specifically, bivalve mollusks bioconcentrate polycyclic aromatic hydrocarbons PAHs. These compounds are a particularly toxic fraction of oil that may cause a variety of chronic toxic effects in exposed organisms, including enzyme induction, immune impairment, or cancer, among others. In addition, because walruses feed primarily on mollusks, they may be more vulnerable to a loss of this prey species than other pinnipeds that feed on a larger variety of prey. Furthermore, complete recovery of a bivalve mollusk population may take 10 years or more, forcing walruses to find other food resources or move to nontraditional areas.
The relatively few walruses in the Beaufort Sea and the low potential for a large oil spill 1,000 bbl or more, which is discussed in the following Risk Assessment Analysis, limit potential impacts to walruses to only certain events i.e., a large oil spill, which is further limited to only a handful of individuals. Fueling crews have personnel that are trained to handle operational spills and contain them. If a small offshore spill occurs, spill response vessels are stationed in close proximity and respond immediately.
Polar Bear To date, large oil spills from Industry activities in the Beaufort Sea and coastal regions that would impact polar bears have not occurred, although the interest in and the development of offshore hydrocarbon reservoirs has increased the potential for large offshore oil spills.
With limited background information available regarding oil spills in the Arctic environment, the outcome of such a spill is uncertain. For example, in the event of a large spill equal to a rupture in the Northstar pipeline and a complete drain of the subsea portion of the pipeline approximately 5,900 bbl, oil would be influenced by seasonal weather and sea conditions including temperature, winds, wave action, and currents. Weather and sea conditions
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