Ancient polar bears survived low ice periods on dead whales: study

Same study suggests bears aren’t likely to be able to rely on the same solution again

New research suggests an answer to the mystery of how polar bears survived previous eras of low sea ice.

But the same paper, published Tuesday in Frontiers of Ecology and the Environment, says the bears aren’t likely to be able to rely on the same solution again.

“I don’t think we can assume what worked in the past is going to work in the future,” said Kristin Laidre of the University of Washington.

Genetic research says polar bears diverged from other bears at least 150,000 years ago and probably as long as 500,000 years ago. That means the species lived through several low-ice periods, including a major warm period about 130,000 years ago.

At that time, while some year-round sea ice is thought to have remained, total coverage was greatly reduced and mostly found in the very highest reaches of the Arctic. Despite the bears needing sea ice to hunt fat-rich seals, somehow they survived.

RELATED: No change to Canada’s climate plans as UN report warns of losing battle

Laidre and her co-author Ian Stirling from the University of Alberta theorize those long-ago bears made it through an extended period of low ice by scavenging whale carcasses washed up on Arctic beaches.

“Polar bears likely survived those periods by accessing stranded marine mammal carcasses, and most likely large whale carcasses,” Laidre said. “They’re such large carcasses that they can be packages of food for, in some cases, years.”

The researchers calculated that a population of about 1,000 bears would need about 20 bowhead whale carcasses to remain healthy through the spring foraging season and about eight carcasses during the summer, when the bears eat less.

They then looked at mortality rates of large whales and what percentage of them might float long enough to wash up on a beach. Those numbers matched well with observed numbers of whale carcasses found in various parts of the Arctic.

A stretch of Russian coastline along the Chukchi Sea, for example, averages about 10 carcasses a year between July and November. A small number of polar bears have learned to rely on that resource.

The numbers suggest that washed-up whales could have been at least a major supplement during poor seal hunting conditions — especially since polar bears are very good at feasting on and storing fat.

“I think they were very likely the main source of nutrition,” said Stirling.

The future of modern polar bears in the face of rapidly shrinking sea ice is much debated, with some arguing their survival through previous low-ice periods bodes well today.

Laidre and Stirling aren’t so sure.

RELATED: Sick orca J50 declared dead by 1 group while scientists remain hopeful

The pace of change is much faster today than in the past. Bears don’t have much time to learn new behaviours on a wide scale.

As well, there aren’t as many whales as there used to be.

“Most of the whale populations have been overharvested,” Stirling said.

At best, he said whale carcasses could buy bears a little more time.

“We may have a little bit longer timeline. Hopefully, we’ll get climate warming under control.

“For the various different species that depend on a polar ice ecosystem, we may be able to keep some of that in its natural condition.”

Bob Weber, The Canadian Press

Like us on Facebook and follow us on Twitter.

Just Posted

What you need to know to vote in Canada’s federal election

Voting guide for Terrace, Kitimat up to Telegraph Creek

B.C. seniors advocate touring Northwest B.C.

Seniors advocate Isobel Mackenzie will be visiting Terrace, Kitimat and New Aiyansh Oct.15-17

Former Terracite Mathew Fee finishes cross-Canada trip on BMX bike

Fee biked more than 7,000 kilometres to raise awareness about addiction treatment

Terrace Search and Rescue headquarters gets $100K boost from Prince Rupert Port Authority

Investment to help grow regional response capacity in Northwest B.C.

Metlakatla, Lax Kw’alaams, Nisga’a and Haisla commit to fight climate change internationally

First Nations launch Northwest Coast First Nations Collaborative Climate Initiative

VIDEO: #MeToo leader launches new hashtag to mobilize voters

Tarana Burke hopes to prompt moderators to ask about sexual violence at next debate

EDITORIAL: Is researched, reasoned journalism the next endangered species?

#Newspapersmatter now more than ever: “In print that privacy is yours to keep”

Cheating husband sues mistress for gifted ring after wife learns about affair

The husband gave his mistress $1,000 to buy herself a ring in December 2017

British couple vacationing in Vancouver, detained in US after ‘accidentally’ crossing border

Parents travelling with three-month-old reportedly being held in Pennsylvania

After losing two baby boys, B.C. parents hope to cut through the taboo of infant death

Oct. 15 is Pregnancy and Infant Loss Awareness Day in B.C.

Alberta to join B.C.’s class-action lawsuit against opioid manufacturers, distributors

B.C. government claims opioids were falsely marketed as less addictive than other pain meds

VIDEO: Trudeau, Singh posture for ‘progressive’ votes while Scheer fights in Quebec

NDP Leader Jagmeet Singh, whose party has been on the rise in recent polls, is campaigning in Toronto

Advance voter turnout up 25% for first two days: Elections Canada

Two million people voted Friday and Saturday

Okanagan principals told to confiscate vaping products from students

Vaping is up 74 per cent in youth over the last two years, according to one Canadian study

Most Read