Publications

Population, habitat, and genetic characteristics of Colorado River cutthroat trout in wilderness and nonwilderness stream sections in the Uinta Mountains of Utah and Wyoming

Jeffrey L. Kershner
Fish Ecology Unit, U.S. Forest Service
Fisheries and Wildlife Department and Ecology Center
Utah State University, Logan, Utah 84322, USA

Dona L. Horan*
U.S. Forest Service, Rocky Mountain Research Station
Boise, Idaho 83702, USA

C.M. Bischoff

Abstract:

 Colorado River cutthroat trout Oncorhynchus clarki pleuriticus, once common in the upper Green River and Colorado River watersheds, are currently limited to less than 1% of their former range and exist in isolated subdrainages in Colorado, Utah, and Wyoming.  We compared stream populations, habitat, and genetic features of Colorado River cutthroat trout (CRCT) in wilderness and nonwilderness areas of the Uinta mountains, Utah-Wyoming.  Densities of adult CRCT were significantly higher in wilderness reaches than in nonwilderness reaches, while densities of juvenile fish showed no difference.  Lengths and weights of juvenile and adult CRCT were significantly higher in wilderness reaches than in the nonwilderness reaches, while densities of juvenile fish showed no difference.  Lengths and weights of juvenile and adult CRCT were significantly higher in wilderness reaches than in the nonwilderness reaches.  Adult habitat quality, as measured by the percent pool habitat, percent undercut bank, mean particle size, and mean stream depth, was significantly higher in wilderness reaches.  Large woody debris and the hydraulic retention of the stream were positively related to juvenile abundance and were both higher in nonwilderness reaches.  Hybridization indices were considered low in all streams on the north slope of the Uinta mountains.  The highest numbers of hybrids between rainbow trout Oncorhynchus mykiss and cutthroat trout were found in streams that were most recently exposed to stocking.  Streams within a designated wilderness in the Uinta mountains represent some of the highest quality habitat for CRCT and exhibit minimal anthropogenic fragmentation.  Wilderness areas may represent some of the last, best opportunities for managing this subspecies within relatively large, intact blocks of habitat.

North American Journal of Fisheries Management 17(4):1134-1143.

Boise Lab Publications List

USDA Forest Service - RMRS - Boise Aquatic Sciences Lab
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