Given a choice between giving birth on land or sea ice, Pacific walrus mothers will most often choose ice.
Likewise, they prefer sea ice for molting, mating, nursing and resting between dives for food. Trouble is, as the century progresses, there’s going to be far less ice around.
The federal government in 2008 listed polar bears as a threatened species because of diminished sea ice brought on by climate warming. That year the Center for Biological Diversity petitioned to do the same for walruses.
“It is unknown whether Pacific walruses can give birth, conduct their nursing during immediate post-natal care period, or complete courtship on land,” said Justice Department lawyers in defending the decision.
A federal judge in Alaska will hear the center’s lawsuit challenging the government’s decision not to list the walrus as threatened. There is no court date set for the lawsuit.
Pacific walrus males grow to 12 feet long and up to 1,815 kg more than an average midsize sedan. Females reach half that weight. Walruses dive and use sensitive whiskers to find clams and snails in dim light on the sea floor.
An Endangered Species Act listing would require the U.S. Fish and Wildlife Service to designate critical habitat for walruses and plan for their recovery. Federal agencies, before issuing permits for development of such as offshore drilling, would be required to ensure walruses and their habitat would not be jeopardised.
Inaccessibility protected walruses for decades, but a rapid decline in summer sea ice has made them vulnerable.
In the Chukchi Sea between Alaska and Russia, where Pacific walrus females and juveniles spend their summer, ice could be absent during that season by 2060 or sooner, according to the Fish and Wildlife Service.
Since 1981, an area more than double the size of Texas 1.58 million square km has become unavailable to Arctic marine mammals by summer’s end, according to the National Snow and Ice Data Center.
By late August, as sea ice recedes beyond the shallow continental shelf, female walruses and their calves face a choice — stay on ice over water too deep to reach the ocean floor for feeding or come ashore for rest periods, where the smallest animals can be crushed in stampedes triggered by a hunter, airplane or bear.
Human intrusion
More open water already has meant more ship traffic. Walruses also could find more humans in their habitat with a reversal of U.S. policy on Arctic offshore drilling. Former President Barack Obama permanently withdrew most Arctic waters from lease sales, but President Donald Trump in April 2017 announced he was reversing Obama, a decision being challenged in court. The administration’s proposed five-year offshore leasing plan includes sales in the Chukchi Sea.
Designating walruses as threatened would mean oil exploration companies would have to consult with federal wildlife officials to make sure drill rigs don’t endanger the animals. However, Trump’s Interior and Commerce departments in July proposed administrative changes to the species law that would end automatic protections for threatened plants and animals and set limits on designating habitat as crucial to recovery.
Walruses are notoriously difficult to count and population estimates range widely. A preliminary one in 2017 put the number at 283,213, with the caveat that it could be as low as 93,000 or as high as 478,975.