Tag Archives: ice coverage

Southern Hudson Bay polar bear region shows slight decline after decades of low sea ice

A newly-published paper by Martyn Obbard and colleagues in the journal Arctic Science claims a 17% decline in abundance of polar bears in the Southern Hudson Bay region after years of reduced sea ice and declining body condition (Obbard et al. 2018). The decline in numbers was not statistically significant but an additional statistical analysis (“Monte Carlo simulation”) not applied to any other estimate in recent years suggested the decline could be real, so a real decline is what was reported to the press.

James Bay polar bear_ministry of Ontario_Walton photo

Only one Canadian Press story has so far been circulated amongst outlets in the media (published hours after the paper appeared online, not at the same time), suggesting there was no press release issued for this study. Odd, that — especially if the decline is as real and significant as the authors suggest.

While no evidence was provided for a correlation of this decline in numbers to recent (2012-2016) sea ice decline, previous evidence from the region (Obbard et al. 2016) showed a decline in body condition was correlated only with much later than usual freeze-up, a situation that did not occur from 2012 to 2015 (freeze-up was late in the fall of 2016 but occurred months after the Obbard et al. (2018) survey was completed).

Moreover, the paper reports that a decline in survival of yearling cubs (from 12% of the population in 2011 to 5% in 2016) was not associated with especially poor sea ice conditions in spring. We are likely to see a follow-up paper next year reporting the body condition and sea ice data from this study (as for the previous survey: Obbard et al. 2015, 2016), but there is no suggestion in this paper that body condition declined further from 2011/2012 levels or that sea ice conditions deteriorated markedly enough after 2012 to precipitate a population decline.

UPDATE 11 June 2018: See below, more recent versions of population and status assessment maps has been issued by Environment Canada that conclude Southern Hudson Bay is “likely declined.”

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Sea ice breakup update: high ice coverage just about everywhere, even Hudson Bay

There is still a lot of sea ice in Hudson Bay, Foxe Basin, Davis Strait and Baffin Bay this week – more than average for this date – with slightly less than average in the Beaufort Sea. Past behaviour of Western and Southern Hudson Bay polar bears suggests the mean date that bears come ashore for the summer this year will be later than average due to the plentiful ice available, regardless of when polar bear biologists decide that “breakup” has occurred.

Hudson Bay breakup July 8 2015_CIS

Hudson Bay, with almost 50% of the bay still covered in ice, has the third highest coverage this week since 1992 (after 2009 and 2004); Davis Strait has the highest coverage since 1992; and Foxe Basin and Baffin Bay have the highest coverage since 1998. For this week, the Beaufort Sea has the second highest coverage since 2006 (after 2013), and more ice than was present in 1971, 1982, 1987, 1988 and 1998 – among others.

Published data shows that most polar bears of Western Hudson Bay traditionally come ashore in July, but this year it might be late July or even August. Have a look at the charts below.
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