Last fall, there were persistent alarms raised about low levels of sea ice in the Chukchi Sea that were echoed this spring. But these low ice levels are not really a serious concern for these polar bears: a 2018 assessment found the bears were in excellent health with no declines in cub production or survival. Funny how little we hear about that.
From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.
See a photo essay of Wrangel Island here and of the islands polar bears here and here.
You also don’t hear about the fact that sea ice has declined by about the same amount in the Chukchi Sea as in Western Hudson Bay. Since 1979, sea ice in the Chukchi Sea has declined at a rate similar to Western Hudson Bay (-0.90 days per year vs. -0.86 days per year, respectively), see graphs below from Regehr et al. (2016, Fig. 2):
While Western Hudson Bay bear numbers have declined slightly in number (by a non-statistically significant amount) and appear to have suffered some recent declines in cub survival (Dyck et al. 2017) (with unsubstantiated claims of declines in adult body condition), Chukchi Sea bears have not (Rode and Regehr 2010; Rode et al. 2013, 2014, 2018).
The fact that Chukchi bears are thriving while Western Hudson Bay bears appear to be struggling, given almost identical trends in sea ice decline, is a connundrum that polar bear specialist are loath to explain.
Only last week, it was announced that the quota for subsistence hunting of Chukchi Sea polar bears had been raised from 58 to 85 due to the excellent status of the population. Polar bear biologist Eric Regehr was quoted as saying:
“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”
So, despite warnings from the polar bear and sea ice “experts” that Chukchi Sea bears may be in dire straits due to recent sea ice declines (see below), it appears that the bears themselves are more resilient to changing conditions than the experts give them credit.
NSIDC sea ice experts cruising the Chukchi Sea took this photo of a polar bear in excellent condition a couple of weeks ago (early August 2018, A. Khan), despite the scary-looking melt ponds: