Straight from the lawsuit paperwork:
"Petitioners include nonprofit groups committed to effective, sustainable and equitable management of trail-based recreation opportunity, as well as fishermen and conservationists committed to active and effective management of Colorado's waters and supported fisheries and aquatic populations. Petitioners, including through their members, reside in the vicinity of Bear Creek, have recreated within the watershed including on all of its Forest Service trails, and have concrete plans to continue such activities to the extent authorized by the Forest Service.
Bear Creek, at least according to the Forest Service, contains "the sole known remaining population of genetically pure greenback cutthroat trout" (Oncorhynchus clarkia stomias). Draft Bear Creek Watershed Assessment, USFS (March, 2013) ("BCWA") at 1 (viewed April 19, 2013 at
https://fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5412309.pdf). The greenback cutthroat trout ("GBCT") is Colorado's state fish and is listed as threatened under the ESA. Id. The Forest Service has taken agency action, most notably through Forest Order 12-21 (December 6, 2012) (attached hereto as Exhibit "A") which has resulted in adverse impacts to GBCT or increased the risk of adverse impacts to GBCT. The Forest Service has exercised its ongoing discretion in a manner that has resulted in adverse impacts to GBCT or increased the risk of adverse impacts to GBCT. This Notice describes on behalf of the Petitioners the alleged violations of the ESA represented by the above-described conduct of the Forest Service."
Sounds like trout fishermen to me

If I'm being totally honest, I don't give a hoot about the Greenback Cutthroat Trout. Sorry. Just another Preble's Jumping mouse "red herring" if you ask me.