There should be a special management designation for the Flathead for sure, but not a national park. National parks in the Canadian Rockies have a poor track record protecting species, esp. charismatic megafauna like grizzly bears. They are species sinks for many species incl. bears; they inadvertenly kill more bears than they protect. Check out the published position papers by the most relevant bear experts in the Cdn. Rockies, like Herrero and Geist, if you don’t believe a random post. It is a simplification, but true, that these national parks cannot properly manage ecosystem values because of their duel mandate to protect nature and to provide access and education to visitors to this nature. It doesn’t work, other than for those who like to ride in tour buses and get a quick pic of their "life list" species. Pretty much like a zoo really, and just as objectionable and requiring constant meddling by well-meaning staff with a goal that is impossible to achieve.
The facts are the Flathead has natural species density, species variety, and species variability. It is more "ecologically healthy" than the mountain national parks. So, it’s pretty simple: what has been going on in the Flathead over the last hundreds of years has worked, so lets not mess with it. It would be naive, however, to believe that all the human activities there have been beneficial or will continue to be so in the future. That is why there has to be some sort of special management of the Flathead put into place, by whom and exactly what I don’t know. But it should ensure continued continued managed hunting and fishing, forestry (properly designed clearcuts are most beneficial to many species; plus increased selective forestry practices), no or extremely limited surface or subsurface resource extraction (mostly because associated industrialization and traffic issues), and it must resist tourism pressures like those in the national parks (paved roads to Mr. Bear and Mrs. Elk’s doorstep, modern facilities, etc.). Maybe something like the Wilmore or White Goat Wilderness areas in Alberta, which adjoin the national parks but are so much better in terms of wildlife species health and diversity. My 30+ years of experience with Banff, Jasper, Yoho, and Kootenay Parks screams to me that it would be such a shame to let our egos think we can do better for the Flathead or that mass tourism that comes with a National Park designation is in any way beneficial – other than to selective interests in the Elk Valley.
So, just to be clear, my vote is "No!"
