Rocky Mountain Research Station Publications

RMRS Online Publication
RM-GTR-282: Conservation status of Colorado River cutthroat trout

Young, Michael K.; Schmal, R. Nick; Kohley, Thomas W.; Leonard, Victoria G. 1996. Conservation status of Colorado River cutthroat trout. General Technical Report RM-GTR-282. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 32 p.

Though biologists recognize that populations of Colorado River cutthroat trout have declined, the magnitude of the loss remains unquantified. We obtained information from state and federal biologists and from state databases to determine the current distribution and status of populations of Colorado River cutthroat trout. Recent population extinctions have been documented throughout this range. Hybridization with rainbow trout, nonindigenous cutthroat trout (those established or supplemented by stocking of genetically pure fish), and introgressed hatchery stocks has degraded many populations of Colorado River cutthroat trout. Only 26% of the remaming populations are believed to be genetically pure. Almost 45% of the remaining populations are at least partly sympatric with non-native trout species or hybridized hatchery stocks. Brook trout are the most common sympatric non-native species. Barriers (permanent, physical obstructions) to upstream migration are known to protect 27% of the indigenous populations from non-native stocks. Land management problems were inconsistently mentioned, but grazing and dewatering were the most frequently cited. As a consequence of these threats, the continued existence of Colorado River cutthroat trout is in doubt. Of the 318 waters, only 20 contain Colorado River cutthroat trout that are believed to be indigenous, genetically pure, allopatric above a barrier, and in a drainage not recently stocked.

Keywords: Colorado River cutthroat trout, Oncorhynchus clarki pleuriticus, extinction, conservation biology

About PDFs: For best results, do not open the PDF in your Web browser. Right-click on the PDF link to download the PDF file directly to your computer. Click here for more PDF help or order a printed copy of this publication.

The PDF below was created by scanning the original printed publication. Errors identified by the software have been corrected but some errors may remain.

Download RM-GTR-282

PDF File Size: 3.2 MB

Title: RM-GTR-282: Conservation status of Colorado River cutthroat trout
Electronic Publish Date: October 5, 2006
Last Update:
October 5, 2006

RMRS Publications | Order a publication | Contact Us