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Let's get the facts right, at least
Posted by bushrat on Feb 04 2006
Mark,
William (Bill) Gassaway was a pretty well-known biologist because of his biometric studies and methods. He is no longer alive. He did not estimate grizzly bear population size in 20E in 2000. That was done by the area biologist at the time, Craig Gardner.
Actually, the "estimate" of the grizzly population in 20E is extrapolated from another study, an intensive CMR study done in the foothills of the AK range 100 miles to the southwest by Reynolds et al. We really don't know the true population size of the 20E bears though Reynolds estimates that since 20E is such similar habitat that the numbers are within 20% plus or minus. Fair enough.
Just an FYI: In many of the management reports you'll see reference to Gassaway or the "Gassaway method" being used to estimate moose densities. This has to do with how biologists aerially survey moose in early winter after the first snow, the initial stratified random sampling of the unit by larger planes to break it down into areas of high and low density, then the sampling (aerial spotting) of both low-density and high-density subunits by spending x amount of time in the air over each square mile of them. Gassaway determined that using his method in the right conditions that we could accurately estimate densities of moose, and for many years this method has been used by biologists in Alaska and Canada and you'll see reference to his name in the reports.
Since Gassaway's passing, biometrician Jay Ver Hoef, who teaches at UAF and also works for ADFG in that capacity, has developed a newer, better method of aerial population estimates, the GSPE method. I forget the acronym definition offhand, but think it is the Global Statistical Population Estimator. If you're a math nut, like me, and enjoy statistics, you might find this interesting: What they were doing with Gassaway's method was using what they call a "sightability correction factor" (SCF) as a sort of margin of error figure. After they'd survey a unit, they'd then fly back over some subunits and recount these areas at a higher "intensity" level (more air time per square mile, flying line transects). They would then come up with a differing count, often more moose, simply because they spent more time in the air circling, and would use this difference as their SCF. Often, such as in the case of bad weather/wind, inadequate snow cover for contrast, these SCF #s were quite high, and gave us a large margin of error factor. Ver Hoef (I interviewed him on this) thought, why re-fly some areas at a higher intensity, why not do the whole survey at this higher intensity to begin with, and thereby eliminate having to use a sightibility correction factor? This is how they now do most density estimates, using Ver Hoef's GSPE method, and they don't use an SCF. There are a lot of variables in these aerial surveys (snow cover, weather during flights etc) but if they are done correctly, during good conditions, they are very accurate samplings. The problem (to me, and some others) lies in some cases when ADFG extrapolates this data over much larger areas that were not a part of the sampling. Such as they did with the 20E estimate for bears.
You are right; there is a lot of conjecture on this issue of bear-control, even among biologists. And varying opinions as well. It's interesting that you and I agree with your own conjecture that this sale of bear hides will probably not result in much increased harvest. The next step is to allow same-day airborne hunting of grizzly bears in 20E, which is up before the BOG at their March meeting. I suppose you (as are others here) are in favor of trying that as well to increase bear harvests? So be it. As I said before, over one million acres of wildfire on top of an 80% wolf reduction in the unit, will probably result in "results" anyway. Killing more bears will only result in having less bears in the field and skewing the age/sex ratio etc. For those of you out there that think that one less bear means more moose, consider what Gardner said in the report: "My observations during calf mortality studies and moose composition data collected in areas of reduced grizzly bear numbers indicate a REDUCED POPULATION OF BEARS IS CAPABLE OF KILLING THE SAME NUMBER OF CALVES, resulting in the same overall calf mortality rate when compared to the periods when bear numbers were not reduced."
So a few more bears will ostensibly be "harvested" for the sale of their hides/claws/skulls. And possibly our BOG will allow same-day airborne hunts for grizzlies in 20E to further give incentive to "hunters" who want to harvest (and sell) a bear. All this so we can ostensibly increase the amount of moose harvest, and increase the amount of moose hunters, in 20E. It's highly interesting that the greatest "management concern" in 20E, as reported by Gardner in the moose report, is the "increasing amount of hunters" and particularly those using atvs. And that to even meet the MIMIMUM harvest objectives called for under Intensive Management in 20E would require a three-fold increase in amount of hunters currently (over)hunting the unit, particularly those using atvs to access areas that Garder states were once "refugia" for moose. If you think it's a bit crowded now off the Taylor Hwy, imagine if instead of 1000 hunters we have 3000 hunters! That's what is required under IM law, and apparently what "hunters" are demanding. I think if more hunters were aware of the real "facts" and repercussions, we might reconsider things.
Looking at it "logically," without emotion, it reads like a Joseph Heller novel.
Mark
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