The end of walrus hunting will have created more food for the bears, who are adapting to the melting ice. However, in the long term, the effects of melting ice will begin to lead to a decline in populations.
Scientists expected otherwise, but polar bears in the Norwegian archipelago of Svalbard became fatter and healthier since the early 1990s, despite sea ice melting having steadily increased due to climate change.
The polar bears depend on sea ice as a platform for hunting seals, from which they obtain the fat necessary for their food.
Fat reserves provide them with energy and thermal insulationand allow mothers to produce nutrient-rich milk for their puppies.
Researchers weighed and measured 770 adult bears in Svalbard between 1992 and 2019 and found that they had become significantly fatter.
They believe that Svalbard bears have adapted to the recent loss of ice consuming more terrestrial prey, such as reindeer and walruses.
The discovery, in the scientific journal Scientific Reports, was particularly intriguing given the impact of climate change on Svalbard.
During the period in which the research was carried out, the increase in global temperatures increased the number of ice-free days per year in the region by almost 100, at a rate of approximately four days per year.
“The fatter a bear is, the better,” explained study lead researcher Jon Aars of the Norwegian Polar Institute.
“I expected to see a decline in the bears’ fitness since the loss of sea ice has been so significant.”
As walruses are officially protected in Norway since the 1950s, after hunting brought them to the brink of extinction.
This protection has boosted their population and, it appears, has provided a new source of high-fat food for polar bears.
“Today there are a lot more walruses for them to hunt,” says Aars. “It’s also possible that they can hunt seals more efficiently.”
Aars explained that if seals have access to smaller areas of sea ice, they congregate in those areas, facilitating group hunting by bears.
“Short-term positive” results
While this is unexpectedly positive news for these Arctic predators, researchers believe this situation is unlikely to continue.
As sea ice continues to melt, bears will have to travel greater distances to access their hunting territories, using more energy and depleting their valuable fat reserves.
The organization Polar Bears International notes that Svalbard’s polar bears were among the most hunted in the world until the implementation of international protection measures in the 1970s.
Experts believe that these new discoveries may be related to the recovery of the population after hunting pressure.
This, coupled with the increase in the number of walruses and reindeer in recent decades, appears to have given a temporary boost to bear population.
John Whiteman, principal investigator for Polas Bears International, said the results were “positive in the short term”.
“But physical condition is only part of the problem. Other recent research on these bears has revealed that a greater number of ice-free days reduced the survival rate of puppies and subadult and elderly females,” he said.
Elsewhere in the Arctic, climate change is having a very different effect on polar bears.
They exist 20 known subpopulations of polar bears across the Arctic.
In Hudson Bay in eastern Canada, where the southernmost and most studied polar bears live, population declines have been directly linked to rising temperatures.
Whiteman added that the long-term outlook for polar bears is clear: They need sea ice to survive.
“The loss of ice ultimately means a decline in bear populationbut [este estudo mostra] that the short-term situation can vary greatly depending on the region,” said Whiteman.
“In the long term, if ice loss continues unchecked, we know that bears will eventually disappear,” the scientist told the BBC.
