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A28 SCIENCE
Tuesday 16 OcTOber 2018

As sea ice melts, some say walruses need better protection

By DAN JOLING that weight. Walruses dive their summer, ice could be Designating walruses as the answer is not so clear
Associated Press and use sensitive whiskers absent during that season threatened would mean cut, and much is unknown
ANCHORAGE, Alaska (AP) to find clams and snails in by 2060 or sooner, accord- oil exploration companies about how sea ice loss will
— Given a choice between dim light on the sea floor. ing to the Fish and Wildlife would have to consult with affect walruses.
giving birth on land or sea Chad Jay of the U.S. Geo-
ice, Pacific walrus mothers logical Survey said it’s un-
most often choose ice. known, for example, why
Likewise, they prefer sea ice female walruses give birth
for molting, mating, nursing on ice instead of land.
and resting between dives “One of the thoughts is that
for food. Trouble is, as the ... there’s more protection
century progresses, there’s for the young from preda-
going to be far less ice tors,” he said. “They’re off-
around. shore, and it’s a cleaner
How well walruses cope environment, too, for giv-
with less sea ice is at the ing birth. But those are hy-
heart of a legal fight over potheses that are difficult
whether walruses should to prove.”
be listed as a threatened A nursing walrus needs to
species, giving them an consume more than 7,800
added protection against clams per day, according
human encroachments. to a federal assessment.
The federal government in And summer is the usual
2008 listed polar bears as time for animals to fatten
a threatened species be- up. When ice melted in
cause of diminished sea alarming quantities, forcing
ice brought on by climate This June 12, 2010, photo provided by the United States Geological Survey shows Pacific walruses females and their calves
resting on an ice flow in the Chukchi Sea, Alaska.
warming. That year the Associated Press to shore in herds as large
Center for Biological Diver- as 40,000, government sci-
sity petitioned to do the Historically hunted for ivory Service. Since 1981, an federal wildlife officials to entists in 2008 tagged and
same for walruses. tusks, meat and blubber, area more than double make sure drill rigs don’t tracked walruses to see
However, the U.S. Fish and walruses since 1972 have the size of Texas — 610,000 endanger the animals. how the changes affected
Wildlife Service concluded been shielded by the Ma- square miles (1.58 million However, Trump’s Interior their feeding.
in October 2017 that wal- rine Mammal Protection square kilometers) — has and Commerce depart- They learned that females,
ruses are adapting and no Act. Only Alaska Native become unavailable to ments in July proposed ad- forced to rest on beaches
one has proven that they subsistence hunters may le- Arctic marine mammals by ministrative changes to the instead of ice, were still vis-
“need” sea ice. gally kill them. summer’s end, according species law that would end iting their favorite feeding
“It is unknown whether An Endangered Species to the National Snow and automatic protections for areas. However, the longer
Pacific walruses can give Act listing would require Ice Data Center. threatened plants and ani- swims drew down fat re-
birth, conduct their nurs- the U.S. Fish and Wildlife By late August, as sea ice mals and set limits on desig- serves critical for lactating.
ing during immediate post- Service to designate criti- recedes beyond the shal- nating habitat as crucial to The walruses should be fine,
natal care period, or com- cal habitat for walruses low continental shelf, fe- recovery. the study concluded, if
plete courtship on land,” and plan for their recovery. male walruses and their Walruses are notoriously dif- they can replace calories
said Justice Department Federal agencies, before calves face a choice: Stay ficult to count — and pop- with additional feeding in
lawyers in defending the issuing permits for develop- on ice over water too deep ulation estimates range winter, but whether that’s
decision. ment such as offshore drill- to reach the ocean floor for widely. A preliminary one happening is unknown.
A federal judge in Alaska ing, would be required to feeding — or come ashore in 2017 put the number at Undernourished females
will hear the center’s law- ensure walruses and their for rest periods, where the 283,213, with the caveat produce smaller offspring
suit challenging the gov- habitat would not be jeop- smallest animals can be that it could be as low as less likely to survive. The de-
ernment’s decision not to ardized. crushed in stampedes trig- 93,000 or as high as 478,975. clining size of polar bear
list the walrus as threat- Inaccessibility protected gered by a hunter, airplane The array of stresses and cubs in the southern Beau-
ened. There is no court walruses for decades, but or bear. uncertainty about the wal- fort Sea was a factor in
date set for the lawsuit. a rapid decline in summer More open water already ruses’ future are enough the decision to list them as
Pacific walrus males grow sea ice has made them has meant more ship traf- evidence for listing them as threatened.
to 12 feet (3.7 meters) long vulnerable. fic. Walruses also could threatened, the Center for Endangered species law
and up to 4,000 pounds In the Chukchi Sea be- find more humans in their Biological Diversity argues. does not require perfect
(1,815 kilograms) — more tween Alaska and Russia, habitat with a reversal of In the last decade, walrus- science to demonstrate
than an average midsize where Pacific walrus fe- U.S. policy on Arctic off- es that gathered on shores adverse effects, Wolf said.
sedan. Females reach half males and juveniles spend shore drilling. Former Presi- have suffered hundreds of When there’s uncertainty,
dent Barack Obama per- stampede deaths, and the she said, the benefit of the
manently withdrew most loss of ice floes has pushed doubt goes to the species.
Arctic waters from lease them away from feeding There have been previ-
sales, but President Don- areas, said Shaye Wolf, cli- ous geological time peri-
ald Trump in April 2017 an- mate science director for ods when walruses expe-
nounced he was reversing the nonprofit conservation rienced a lack of sea ice,
Obama, a decision being group. said Jay.
challenged in court. The “They’re not adapting. “Maybe they can get
administration’s proposed They’re suffering,” Wolf through that sort of an en-
five-year offshore leasing said. vironment. Maybe they
plan includes sales in the Scientists advising the Fish can’t,” he said. “No one re-
Chukchi Sea. and Wildlife Service say ally knows.”q