The US Fish and Wildlife Service’s recently released Oil Spill Response for Polar Bears in Alaska focuses on keeping oil away from polar bears, acknowledging that there is limited capacity to care for these large marine animals once they are oiled.
And, while the plan is for response in the US, the focus on keeping the oil away from the animals make sense for many species. Placing booms around sensitive habitat, using various deterrents and, for some species, pre-emptive capture, are now considered among the primary response tools. For example, during the 2011 response to the M/V Rena in New Zealand, fur seals and dotterels were pre-emptively captured to prevent oiling. And in 2000, during the response to the M/V Treasure in South Africa nearly 20,000 African penguins were captured and relocated to prevent them being oiled.
Polar bears, like sea otters and fur seals, are reliant on their dense coat for warmth. In fact, their fur, which appears white, is actually translucent with a complex interior structure that absorbs heat so efficiently the bears are able to maintain a body temperature of 37C even when ambient temperatures reach -60C. If the fur loses its ability to absorb light, the animals quickly become hypothermic. Polar bears are also highly susceptible to liver damage from ingesting oil while grooming. Equally important, these large, powerful animals are difficult to capture and confine.
Based on these concerns, the plan prioritises containment and in-situ burning to prevent oil reaching important polar bear habitat. Deterrents to keep the animals away from the oil would be the next step. Should polar bears become oiled, only a few animals could be treated at any one time, as facilities and equipment for cleaning and rehabilitating them are limited. Priority would be given to family groups and adult females with a high likelihood of survival.
Walrus capture and care also problematic
An article in the Alaska Dispatch News also looks the potential for response to other large marine mammals such as walrus. The plan for response to walruses is under review but according to James MacCracken, a walrus biologist with USFWS, response to oiled walrus would also be limited. Walruses are often found hauled out in large packs, thus attempting to capture oiled animals would likely result in stampedes, with animals being injured or killed by one another.
Walruses are also difficult to sedate safely and sedation would be needed to clean adult animals. So it is unlikely that any walruses, other than orphaned calves would be cleaned. On the positive side, walruses rely on blubber, not fur for warmth so they would be less likely to suffer from acute effects of oil exposure. Still, the optimum response for them would be similar to that proposed for polar bears— keeping the oil away from their known haul outs and using deterrents to keep them from oiled areas.
How to de-oil a polar bear: Grim outlook for wildlife impacts from an Arctic spill. Alaska Dispatch News. Accessed online August 2015
Oil Spill Response for Polar Bears in Alaska. USFWS document. Accessed online August 2015
Inside polar bear hair: a complex, heat-holding labyrinth of pores. Alaska Dispatch News. Accessed online August 2015