No Reliable Data on Historical Polar Bear Numbers - A Note from Nichole Hoskin

Polar bears (Ursus maritimus) have become a symbol of global warming, and their predicted decline a sign of worst to come, but until very recently population estimates were really just educated guesses. Current polar bear numbers are estimated to total between 20,000 and 25,000.

On May 14 2008, when announcing the decision to list polar bears as threatened under the U.S. Endangered Species Act, Secretary for the U.S. Department of Interior, Dirk Kempthorne stated,

“Although the population of bears has grown from a low of about 12,000 in the late 1960’s to approximately 25,000 today, our scientists advise me that computer modeling projects a significant population decline by the year 2050.”

But there are no published papers or reports to support the claim that there were about 12,000 polar bears forty years ago.

At the 1968 meeting of International Union for the Conservation of Nature (IUCN) Polar Bear Specialist Group in Alaska, the Canadian Wildlife Service representatives suggested that numbers were as low as 5,000 in the 1950s and 1960s.

Current Chairman of the IUCN Polar Bear Specialist Group, Andrew Derocher, has stressed,

“The early estimates of polar bear abundance are a guess. There is no data at all for the 1950-60s. Nothing but guesses. We are sure the populations were being negatively affected by excess harvest (e.g., aircraft hunting, ship hunting, self-killing guns, traps, and no harvest limits). The harvest levels were huge and growing. The resulting low numbers of bears were due only to excess harvest but, again, it was simply a guess as to the number of bears.”

But how can Dr Derocher be sure that polar bear populations were being negatively affected by harvesting if there is no hard data on population numbers for the same period?

In 1972, at the 3rd Working Meeting of the IUCN Polar Bear Specialist group the Norwegian representative, Thor Larson, suggested there were as many as 20,000 in the late 1960s. Larson said,

“Merely by summarising the various national counts, which still must be considered inaccurate, one reaches the conclusion that the worlds total polar bear population is probably closer to 20,000 animals, than to the lower figures often suggested.”

Just maybe there have always been about 20,000 polar bears in the Arctic?

Nichole Hoskin is a research assistant at the Institute of Public Affairs and is adding to the Environmental Wiki associated with this blog.

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Other blog posts by Nichole Hoskin on polar bears include:
Polar Bears Can Survive where there is no Summer Sea Ice: A Note from Nichole Hoskin, August 20, 2008.

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