Warming Drives Massive Migration of Walruses
Scientists investigate massive walrus haul-out in Alaska
Scientists fear declining Arctic sea ice may have caused an unprecedented mass migration to dry land
The Guardian (U.K.), Sept. 13, 2010
Scientists in the
Arctic are reporting a rare mass migration of thousands of walrus from
the ice floes to dry land along Alaska's coast.
Researchers from the US Geological Survey (USGS) who have been tracking walrus movements
using satellite radio tags, say 10,000 to 20,000 of the animals, mainly
mothers and calves, are now congregating in tightly packed herds on the
Alaskan side of the Chukchi Sea, in the first such exodus of its kind.
"It's something
that we have never seen before in this area," said Geoff York, of the
WWF's global Arctic programme. "As the ice decreases, the walrus are
abandoning it earlier and earlier. They are having to swim ashore, or to
linger on less suitable drift ice for long periods of time."
The flight of the
walrus, first reported by the Alaska Dispatch, has reinforced warnings
from scientists that the lumbering animal may be headed for extinction
because of climate change.
Arctic sea ice
dropped to its third lowest level in recorded history this month. The
USGS study noted that the entire Chukchi shelf could be completely
ice-free during August, September and October by the end of the century.
The USGS, which
has been tracking the walrus since June, put the chances of extinction
or serious population decline among walrus at 40% by 2095 because of the rapid and widespread loss of summer sea ice due to warming temperatures.
Walrus are not the only animals facing depleted numbers or
extinction because of climate change. The Arctic is warming at twice
the rest of the world on average, and its seas are growing increasingly
acidic because of increased concentrations of carbon dioxide. A new
report today warned that 17 species - from tiny plankton to the weighty
narwhal - were threatened by the disappearing sea ice and rising seas.
In addition to polar bear – whose plight is widely recognised – and walrus, the report from the Centre for Biological Diversity said several species of whale and seal, and land-based animals such as caribou and fox were facing declines.
Meanwhile, local
residents in Point Lay told the Dispatch the numbers of walruses coming
ashore could be much higher than government estimates.
The rare onshore
mass sightings have raised fears of a grisly repeat of last summer when
some 130 of the beasts, mainly calves, were trampled to death as the
herd foraged for food.
"Walrus mums and
calves need the sea ice to rest," said Shaye Wold of the Centre for
Biological Diversity. "When the sea ice disappears they are forced to
come to shore and their calves are extremely vulnerable to being
trampled in a stampede as you can imagine with 10,000 to 20,000 walruses
on shore trying to forage in a limited area."
Because of their
huge girth, walrus are relatively clumsy in water. During their annual
migration, they rely on large floating patches of ice as resting stops
or mobile fishing platforms as they make their voyage cross the shallow
frigid waters between Alaska and Russia.
In 2007 and again
last year "thousands of walruses hauled out along the coast of
north-western Alaska and tens of thousands of walruses hauled out along
the coast of northern Chukotka when ice disappeared," the USGS report
said. "These events led to the trampling and death of hundreds of
walruses in Alaska and thousands in Russia," the report said.
Increased
concentrations of carbon dioxide in the ocean was also depleting the
walruses' food supply, making the waters too corrosive for the clams and
other shellfish that are their staple.
The USGS study
went on to note that disappearing summer sea ice, due to climate change,
was likely to spur an increase in shipping traffic through the Chukchi
and Bering seas, putting the walruses in further jeopardy.
In a statement,
Rebecca Noblin, the director of the Centre for Biological Diversity,
argued that the forecast failed to take stock of the risks of oil spills
in the pristine Arctic environment, because of the increase in
shipping, or the potential for damage if the area is opened up for
offshore oil and gas drilling.
"Unless we dramatically reduce our greenhouse emissions, the walrus is on a trajectory toward extinction," Noblin said.
The centre
launched a law suit two years ago to place the Pacific walrus on the
list of endangered species. The federal government must rule by January
2011 whether to grant endangered species protection to the Pacific
walrus, which would put restrictions on offshore oil drilling and
shipping routes through the Arctic.
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