In the chiaroscuro of the polar winter, the whirling of hundreds of seagulls above the waters of a Norwegian Arctic fjord signals the feasting of a group of predators.
With the retreat of the pack ice caused by accelerated global warming in the Arctic Ocean, orcas are spending more and more time in its waters, expanding their hunting area further north, according to scientists.
On this frozen day in the Norwegian Far North, 70 to 80 killer whales point their big fins in the vast Skjervøy fjord, gathered by family clans of a dozen killer whales, including very young born of the year.
Reports, more and more frequent and from the north, suggest that the dreaded “killer whale” is adapting to the new profile of the Arctic Ocean, where the sea ice surface is drastically reduced.
“We have beacon returns where we see orcas which in November are in the Barents Sea, between the eastern part of Svalbard (in the north of Norway) and François-Joseph land (in the Russian Arctic) therefore clearly they follow the edge of the ice, “Marie-Anne Blanchet, professor at the Norwegian Polar Institute in Tromsø, told AFP.
The killer whale, whose versatility allows it to go to almost all the seas of the globe, offers itself new arctic prey such as the beluga and probably certain species of seals living on the ice, underlines the specialist.
The phenomenon is also linked to the fact that the herring, the killer whale’s delicacy, also migrates further and further north, for reasons which are still hypothetical.
“They are predators who have a great capacity to adapt, so they are opportunists,” said Ms. Blanchet.
These new hunting grounds also create new conflicts between animals (world population estimated at 50,000) and humans, in places where they were hardly ever observed.
In the fjord of the Greenlandic capital Nuuk, four orcas were killed at the end of November – which is not illegal in Greenland.
According to a study from the University of Washington presented in early December, this increased migration of superpredators is the consequence of the increasingly long season when the Arctic Ocean is free of ice.
Killer whales are most commonly seen in the Chukchi Sea, between Alaska and the Russian coast, according to the study, based on eight years of acoustic listening.
In this area, killer whales are increasingly preying on bowhead whales, a species more exposed by receding sea ice.
These attacks “are likely to increase due to the longer seasons of the ice-free ocean”, stress the American researchers.
The Arctic is warming three times faster than the rest of the planet, weighing heavily on the size of sea ice and the ecosystems that depend on it.
On average, the extent of the Arctic sea ice, which is also shrinking, has declined by more than 13% per decade over the past 40 years.
By the end of summer 2012, it had reached its lowest level on record, at 3.4 million square kilometers, compared to almost double in the 1980s.