Is ‘Pacific walrus’ a threatened species?

Drought blamed

ANCHORAGE, Alaska, Sept 28, (Agencies): A federal agency faces a deadline this week to decide whether the iconic Pacific walrus will join the polar bear on the threatened species list.

The US Fish and Wildlife Service under a court settlement has until Saturday to decide whether the Pacific walrus should be put on the list because of threats to its sea ice habitat due to climate change.

Walruses use sea ice as platforms for resting, feeding and nursing. In spring, ice in the Bering Sea melts and the edge gradually recedes north through the Bering Strait and into the Chukchi Sea.

Shaye Wolf, climate science director for the Center for Biological Diversity, in February 2008 filed the petition that called for the listing. The need has not diminished, she said Tuesday.

“The science is absolutely clear that the walrus is in trouble from climate change and it’s already waited much too long for protection,” Wolf said.

President Donald Trump has called climate change a “total con job” and “hoax” perpetrated to harm US economic competitiveness.

He has pushed to scrap Obama-era initiatives that sought to reduce carbon emissions from coal-fired power plants and other sources and announced that the country would pull out of the 2015 Paris climate accord, in which nearly 200 nations pledged to reduce carbon emissions.

The state of Alaska in unsuccessful lawsuits challenged the listing of polar bears and ringed seals and opposes the walrus listing.

State Division of Wildlife Conservation director Bruce Dale said Wednesday that the walrus population is robust and listing the species based on uncertain future climate change is not justified.

“They’ve gone through periods of warming before,” Dale said of walruses. “All these species have. That in itself doesn’t mean that they’re in jeopardy of extinction.”

Male walruses in summer mostly remain in the Bering Sea, resting on remote coasts when they’re not foraging.

Females with calves ride the ice north like a conveyor belt. The females dive for clams, sea snails and other mollusks on the shallow continental shelf while pups rest on ice. As ice recedes, the pack edge is continuously over new feeding grounds.

In recent years, however, as the Arctic has warmed, ice has receded beyond the shallow shelf to water more than 10,000 feet (3,050 meters) deep, far too deep for walrus to reach the ocean floor.

Wolf

Instead of remaining on ice over deep water, females with calves have congregated on shore in northwest Alaska and Russia, sometimes in herds of 40,000.

The animals pack beaches, ready to rush to the safety of the water if they perceive danger. When herds are spooked by polar bears, hunters, airplanes or boats, walrus stampedes into the ocean can crush the smallest animals.

A Sept 11 survey of a mile of beach near the tiny northwestern Alaska village of Point Lay recorded 64 mostly young dead walruses likely killed in stampedes. That followed 131 walruses found dead in September 2009 at Icy Cape about 140 miles (225 kms) southwest of Utqiagvik, formerly known as Barrow.

Climate models project sea ice could disappear, even over deep water, for part of the summer by midcentury, Wolf said.

“Stopping the climate denial, getting momentum nationally at all levels and cutting our greenhouse gas pollution, that’s absolutely the key to walruses’ survival,” Wolf said.

Projections of future sea ice rely on climate modeling and there’s uncertainty with models, Dale said. Some argue that listing high-profile species calls attention to global warming, Dale said, but it comes at a cost. “It’s a diversion of resources from meaningful conservation,” Dale said. “That’s not what the act was intended for.”

Both Dale and Wolf expect a decision this week. If the federal government denies the walrus listing, the decision likely would be challenged in court, Wolf said. Interior Department and US Fish and Wildlife Service officials did not respond immediately Wednesday to email requests for comment.

SYDNEY:

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The mystery loss of Tasmanian tigers from mainland Australia was likely caused by climate change and not wild dogs or hunting by Aborigines, scientists said Thursday.

The enigmatic animal — also known as the thylacine — was once widespread across the vast country, but was wiped out on the mainland around 3,000 years ago.

They survived in the southern island state of Tasmania until 1936 when the last known one died in captivity at Hobart Zoo after the species was hunted to extinction in the wild.

One previous theory on why the marsupials vanished from the mainland blamed the introduction by seafarers of wild dogs known as dingoes around 3,500 years ago. Dingoes have never lived in Tasmania.

Another suggested hunting by Aborigines pressured the population of the dog-like animal with stripes on its back, which remains one of Australia’s most mythical creatures — with some believing they still survive today.

But a study published in the Journal of Biogeography this week, based on ancient DNA extracted from fossil bones and museum specimens, has now concluded their mainland extinction was likely triggered by drought.

Researchers from the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) created the largest dataset of thylacine DNA to date with 51 new genome sequences and used it to track population sizes through time.

“The ancient DNA tells us that the mainland extinction was rapid, and not the result of intrinsic factors such as inbreeding or loss of genetic diversity,” said lead author Lauren White.

A large and genetically diverse thylacine population lived in parts of southern Australia until three millennia ago, when more drought-prone seasons caused by the onset of the El Nino weather system likely wiped them out, the scientists found.

“We also found evidence of a population crash, reducing numbers and genetic diversity of thylacines, in Tasmania around the same time,” said ACAD deputy director Jeremy Austin.