More bad science: US biologists successfully used a scientifically flawed model to get polar bears listed as ‘threatened’ and thus emboldened, went on to do the same for walrus.
The intricate US Geological Survey model of ‘expert opinion’ that was used to support the listing of polar bears as ‘threatened’ under the US Endangered Species Act (ESA) has been soundly rejected by the world’s leading conservation organization, the IUCN,1 which has has tightened its rules for using “future conditions” (e.g., effects of global warming) in generating Red List assessments. That IUCN condemnation means the USGS model was never “the best available science” for evaluating the status of polar bears ̶ it was (and still is) substandard, inadequate science that makes a mockery of serious conservation efforts.
However, not only has this flawed model continued to be used by the USGS for polar bears, it has also been used to assess the conservation status of Pacific walrus, which are now officially “candidates” for being listed as ‘threatened’ (US Fish and Wildlife Service 2011).2
It turns out that an updated version of the USGS polar bear model was released earlier this year (Atwood et al. 2014), without fanfare, apparently as part of a required polar bear “recovery” plan.3
The so-called “2nd generation” model used in this document simply added a few more expert opinions to the complex and numberless Bayesian Network model [“numberless” in the sense that no population numbers were used]. That’s up from the single expert opinion (Steven Amstrup) used in the 2007 version of the model (Amstrup et al. 2007, 2008), which supported the 2008 ESA listing of ‘threatened’ (US Fish and Wildlife Service 2008) — but a substantial improvement of the method it is not.
Compounding the 2007 model errors, the same flawed approach was used in 2011 to assess the potential future of walruses (Jay et al. 2011; Oakley et al. 2012). This partially explains the hysteria over last fall’s brief gathering of a large walrus herd on an Alaskan beach, now an annual event similar to the hue and cry about polar bears generated every September when the annual sea ice extent minimum is reached.
And, surprise, surprise: no reports of huge numbers of dead or dying walruses associated with this incident, even in a March 2015 follow-up. The ‘walruses are in peril’ issue simply faded into the background once the PR value of the haulout event had been realized (see summary posts here and here, video below).
In a nutshell: Bayesian Network models used by USGS for conservation status assessment are scientifically defective, which means they are just as scientifically deficient for walrus. Bad science replicating like a virus is still bad science. With the bar for conservation science set so low, is it any wonder that the US is the world’s leader in listing marine mammals as ‘threatened’ with extinction?
Footnote 1. Problems with the models [from 29 November 2014]
“Leading the polar bear prediction critique is distinguished professor of Ecology and Evolution, and mathematical modeling expert, H. Resit Akçakaya from Stony Brook University, New York (see Reference section) – who also happens to Chair the Standards and Petitions Subcommittee for the IUCN Red List.
Referring specifically to Amstrup and colleagues’ Bayesian Network model papers, Professor Akçakaya had this to say to PBSG members (including Amstrup) at their June meeting:
“First, BN models are mainly a vehicle for placing expert opinion into a common framework. They are not straightforward to update on the basis of observed data and there is concern that data would not be able to overwhelm the priors. Second, the BN model structure is not based on population dynamic theory. Third, the results from the BN approach are not applicable to Red List Criteria A or C, which require estimates of the amount of the decline not the probability of decline. Finally, the results are not applicable to Red List Criteria E, which requires quantitative not qualitative states.” [my bold]
The only criteria available to the PBSG for making a case that polar bears should be classified as ‘vulnerable’ on the next IUCN Red List is to use Criteria A3 (“population reduction expected in future”), in conjunction with Criteria E (“any form of analysis that estimates the extinction probability of a taxon based on known life history, habitat requirements, threats, and management options”).
By all other IUCN criteria, polar bears are currently either ‘data deficient’ or ‘least concern’ — only a much-revised PBSG assessment (with more data), that predicts population declines ≥30% within 30-36 years, will allow polar bears to be listed as ‘vulnerable’ by the IUCN Red List in 2015. PBSG-member biologists are scrambling to pull their case together, focusing their efforts on preventing an IUCN demotion of polar bear status.
[New IUCN guidelines were made available in February 2014, with specific reference to dealing with future risks from climate change – see them here]
Footnote 2. In checking a few details while writing this post, I came upon this interesting statement: Decisions Informed by the USGS Changing Arctic Ecosystems Initiative: Upcoming Pacific Walrus Endangered Species Listing Act Decision by the USFWS
“In 2011, the U.S. Fish & Wildlife Service determined that listing of the Pacific walrus as a threatened species under the Endangered Species Act was warranted but precluded by higher priorities. USFWS is under a court order to make a decision on walrus by 2017. In the USGS Changing Arctic Ecosystems Initiative, the USGS is undertaking a suite of studies to refine forecasts of future status of the Pacific walrus population. These studies include tracking studies to understand walrus movements and activity budgets under differing ice conditions; development of a population model and collection of current data on age structure to inform an assessment of trend; and development of an energetic model to link changes in sea ice with changes in activity and ultimately population dynamics.” [my bold]
Footnote 3. USGS Announcement, 13 January 2015 [not a press release] of the Atwood et al. 2014 publication: New publication examines factors influencing persistence of polar bears.
“Alaska Science Center scientists Todd Atwood, Dave Douglas, Karyn Rode, George Durner, and Jeff Bromaghin authored an open file report evaluating the relative influence of plausible stressors on the long-term persistence of polar bears. Using an updated Bayesian network model previously used to forecast the future worldwide status of polar bears, they found that polar bear outcomes worsened over time through the end of the century under both stabilized and unabated greenhouse gas emission pathways. The unabated greenhouse gas emission pathway hastened the time it took for some polar bear populations to reach a greatly decreased state. The most influential drivers of adverse population outcomes were declines to sea ice conditions and to the marine prey base. Stressors associated with in situ human activities exerted considerably less influence on outcomes. The findings also suggest that the adverse consequences of loss of sea ice habitat are likely to become more pronounced as the summer ice-free period lengthens beyond 4 months, which could occur in portions of the Arctic by the middle of this century under the unabated greenhouse gas emission pathway. The range-wide persistence of polar bears will likely require stabilizing CO2 emissions by the middle of this century.”
Amstrup, S.C., Marcot, B.G. and Douglas, D.C. 2007. Forecasting the range-wide status of polar bears at selected times in the 21st century. Administrative Report, US Geological Survey. Reston, Virginia. http://www.usgs.gov/newsroom/special/polar_bears/
Amstrup, S.C., Marcot, B.G., Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pgs. 213-268 in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, E.T. DeWeaver, C.M. Bitz, and L.B. Tremblay (eds.). Geophysical Monograph 180. American Geophysical Union, Washington, D.C. http://onlinelibrary.wiley.com/doi/10.1029/180GM14/summary and http://alaska.usgs.gov/science/biology/polar_bears/pubs.html
Jay, C. V, B. G. Marcot, and D. C. Douglas. 2011. Projected status of the Pacific walrus (Odobenus rosmarus divergens) in the twenty-first century. Polar Biology 34(7):1065-1084. doi: 10.1007/s00300-011-0967-4 http://link.springer.com/article/10.1007%2Fs00300-011-0967-4
Oakley, K., Whalen, M., Douglas, D., Udevitz, M., Atwood, T., and Jay, C. 2012. Changing Arctic Ecosystems: Polar bear and walrus response to the rapid decline in Arctic sea ice. U.S. Geological Survey Fact Sheet 2012-3131. http://pubs.usgs.gov/fs/2012/3131/
US Fish and Wildlife Service. 2008. Determination of threatened status for the polar bear (Ursus maritimus) throughout its range. Federal Register 73(95):28212-28303.
US Fish and Wildlife Service. 2011. 12-month finding on a petition to list the Pacific walrus as endangered or threatened. Federal Register 76(28):7634-7676.
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