see it here: http://www.flyanglersonline.com/articles/journal/2013/journal20130826.php
I believe the NPS efforts to "remove" all non-native fish in the park is just the first step. Once well underway they will move to eventually "eliminate" the "harassing" of fish (wildlife) in the park by anglers.
The top of the arch is inscribed with a quote from the Organic Act of 1872, the legislation which created Yellowstone, which reads "For the Benefit and Enjoyment of the People."
The management of the park by the NPS will continue to be an ongoing struggle for anglers for the foreseeable future, IMHO.... Doug Korn