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Cutthroat Trout


Rio Grande cutthroat trout (RGCT; Oncorhynchus clarkii virginalis); Westslope cutthroat trout (WCT; Oncorhynchus clarkii lewisi)

Principal Biologist(s)

Carter G. Kruse

Project Location

Multiple locations

Conservation Problem

Range-wide declines primarily due to competition and introgression with introduced salmonids, but also from habitat degradation and exploitation. RGCT were historically found in about 10,700 km of habitat in the upper Rio Grande basin of Colorado and New Mexico, however the distribution of genetically pure populations of this subspecies has been reduced by 92%. WCT were historically the most widespread cutthroat subspecies – occupying an estimated 90,800 km of streams and rivers throughout the Columbia and Missouri basins headwaters of Montana, Wyoming and Idaho – but the range of genetically pure populations has been reduced by 76%. On the east side of the Continental Divide range reduction has been even more dramatic, exceeding 95%.

Conservation Status

RGCT were listed as a federal candidate species under the Endangered Species Act (ESA) in 2008 and are currently undergoing another status review for listing determination. The subspecies is considered a Species of Greatest Conservation Concern/Need by the New Mexico Department of Game and Fish and Colorado Parks and Wildlife. WCT are not listed under ESA, but are considered a Species of Greatest Conservation Need by Montana Fish Wildlife and Parks and Idaho Department of Fish and Game. Both subspecies are considered Sensitive by the US Forest Service.

Project Goals & Objectives

Range-wide conservation agreements among management agencies and non-governmental organizations are in place to guide conservation and restoration activities for WCT and RGCT across jurisdictional boundaries. Objectives outlined in these documents include: securing and monitoring known cutthroat trout populations; seeking opportunities to restore or found new populations, especially over large areas and including private lands; identifying or locating any additional wild populations; coordinating conservation activities among resource agencies and non-governmental organizations; and providing public outreach and technical assistance. These range-wide objectives for cutthroat trout conservation are consistent with the mission of Turner Enterprises and fit within the land management framework on the ranches. Most importantly, the Turner family has been supportive of cutthroat restoration, embracing the risks inherent with large-scale native trout restoration. The Turner Biodiversity Divisions have developed a Cutthroat Trout Initiative with a goal of catalyzing cutthroat restoration or conservation activities on 400 km of stream. This is by far the most comprehensive and ambitious private effort on behalf of native cutthroat trout. Efforts to restore or conserve cutthroat trout are in planning or underway in eight streams on four ranches; not all may ultimately be implemented or successful but they provide the framework to reach our goal. These projects all have similar objectives, with an overall intent of improving the range-wide status of RGCT and WCT and preventing listing under ESA:

1.  Selection of re-introduction sites encompassing a large geographic area with high quality and diverse habitats to support a robust cutthroat trout population with diverse life-history strategies able to resist threats such as climate change, catastrophic events, and invasive species.

2.  Elimination of non-native competitors in the re-introduction site (watershed or portion thereof) through physical and/or chemical renovation, and prevent their recolonization.

3.  Establishment of a self-sustaining population of cutthroat trout large enough to withstand environmental and demographic stochasticity and likely to persist over the long-term (> 100 years) with little or no human intervention.

4.  Establishment of a monitoring strategy, including relevant research partnerships, that evaluates key project aspects and allows adaptive management of all strategies and methods as the project unfolds, and to improve and guide future efforts.


Project Background