Rio Grande Cutthroat Trout
Rio Grande cutthroat display a variety of colorations including bright crimson red and orange on the belly. The sides of the fish are golden yellow trending to a greenish hue on the back. They have large spots concentrated near the tail.
About This Species
Native trout. Rio Grande cutthroat trout, Oncorhynchus clarkii virginalis, can be found in high elevation streams and lakes of the Rio Grande, Canadian, and Pecos River drainages in Colorado and New Mexico, giving it the southern-most distribution of any form of Cutthroat Trout. It now only occupies just 12 percent of its historic habitat in approximately 800 miles of streams. Biologists estimate that 127 conservation populations now exist in the two states, and 57 of those populations are considered to be secure. The historic range of Rio Grande cutthroat trout has been reduced over the last 150 years due to many changes on the landscape, including: drought, water infrastructure, habitat changes, hybridization with nonnative Rainbow and Cutthroat Trout, and competition with Brook and Brown Trout. As a result, pure populations of Rio Grande Cutthroat Trout are restricted primarily to headwater streams.
State Wildlife Action Plan
Tier 1 Species
The Rio Grande cutthroat trout is currently a candidate for listing protection under the Endangered Species Act of 1973. The U.S. Fish and Wildlife Service will make a decision on whether or not to list the Rio Grande cutthroat sub-species in 2014. Trout Unlimited supports the efforts of the Range Wide Conservation team that has been working to protect, conserve, and restore populations of RGCT for over a decade.
Researching and Protecting Cutthroat Trout
There are four native subspecies of cutthroat trout in Colorado: the Colorado River Cutthroat, the Rio Grande Cutthroat, the Snake River Cutthroat and the native Greenback Cutthroat trout. Colorado researchers are also currently attempting to find the thought-extinct Yellowfin Cutthroat trout. All subspecies of cutthroat trout are the subject of conservation efforts and research by multiple state and federal agencies.
The beautiful and vibrant cutthroat trout gets its name from the red slash under its jaw. The cutthroat's medley of colors and spots make it one of the most cherished fish among Colorado anglers. Colorado is home to three subspecies of native cutthroat: the Rio Grande, Colorado River and the renowned greenback, which was designated Colorado's state fish in 1994. But, despite its iconic stature, the plight of the cutthroat has been both challenging and uncertain. For decades, cutthroat trout populations have declined throughout the western United States.
Working with a consortium of state and federal wildlife agencies, Trout Unlimited and other conservation groups, Colorado Parks and Wildlife (CPW) has developed an aggressive conservation strategy to help restore native cutthroat populations. A key component of cutthroat conservation is egg-collection, hatchery and stocking programs.
Genetic research led by University of Colorado scientists has produced several fascinating discoveries about Colorado's native cutthroat trout - including the location of the last surviving wild population of the federally protected greenback cutthroat trout.
Researchers analyzed DNA extracted from wild trout and from museum specimens collected from sites around Colorado and New Mexico as far back as 1856, then used that genetic data as a baseline for understanding the current distribution of Colorado's native cutthroat trout.
In addition to identifying the one remaining "true" greenback population, researchers identified two distinct genetic lineages within the range of Colorado River cutthroat trout, one in northwest Colorado and the other centered around the Gunnison River basin. Further research will be needed to understand the relationship between these two lineages.
In all, six lineages of cutthroat appear to have evolved in Colorado, with native ranges that roughly correspond to major drainage basins in the state. The greenback cutthroat trout, Colorado's state fish, was native to the drainages of the South Platte, while the long extinct yellowfin cutthroat trout of Twin Lakes actually appears to have been the native trout of the Arkansas River Basin. Rio Grande cutthroat trout still can be found in streams that drain into the San Luis Valley, while a lineage that used to call the San Juan basin home appears to be extinct as well. More research will be required to resolve whether the remaining two lineages that can be found across Colorado’s western slope are indeed two distinct subspecies – that work is ongoing.
Given that additional lineages of our native cutthroat trout were identified with the DNA testing, we wanted to determine if these lineages displayed different physical characteristics as well. This is particularly important since it has been argued that genetics should not be the sole factor in determining taxonomic distinctions, and that morphological traits (visual characteristics) are often better suited for discriminating taxa. A recent comprehensive study examined the relationship between the differences implied by the DNA and the morphology of these fish. Indeed, it appears that these new lineages can also be identified by examining morphological traits as well.
A key element of cutthroat trout conservation involves the ability to take fertilized eggs from wild populations. Progeny from these operations are used for founding new populations in waters that have been cleared of nonnative fish that otherwise replace cutthroat trout or hybridize with them. Where habitats home to pure cutthroat trout have been invaded by nonnative salmonids, it important to replicate those populations before they wink out. Improving methods for obtaining fertilized eggs in the wild will facilitate those efforts.
Like many coldwater fish species, cutthroat trout will face numerous additional challenges in a warming climate (see Dan Isaak's climate blog). State and federal researchers teamed up with Dr. Kurt Fausch of Colorado State University to develop a robust approach for synthesizing the myriad factors that will influence the persistence of remaining 121 individual conservation populations of Rio Grande cutthroat trout to 2080. Recently published as a featured paper in the North American Journal of Fisheries Management titled “Predicting persistence of Rio Grande Cutthroat Trout populations in an uncertain future”, the study found that although streams are predicted to warm by 2080, less than 10% of populations will be adversely affected. In contrast, nearly 65% are predicted to be extirpated (or nearly so) by nonnative trout that have already invaded or are expected to soon. Many populations will require the help of managers if they are to persist well into the 21st century. A manual for running the model can be found by clicking the link below.
More Information:
Physical Characteristics
Rio Grande cutthroat size is variable, and based on the available habitat. In small headwater streams adults are generally 6-10˝ in length
Commonly Found
Rio Grande cutthroat trout can be found in high elevation streams and lakes of the Rio Grande, Canadian, and Pecos River drainages in Colorado and New Mexico, giving it the southern-most distribution of any form of Cutthroat Trout. It now only occupies just 12 percent of its historic habitat in approximately 800 miles of streams.
Range
Biologists estimate that 127 conservation populations now exist in the two states, and 57 of those populations are considered to be secure. The historic range of Rio Grande cutthroat trout has been reduced over the last 150 years due to many changes on the landscape, including: drought, water infrastructure, habitat changes, hybridization with nonnative Rainbow and Cutthroat Trout, and competition with Brook and Brown Trout. As a result, pure populations of Rio Grande Cutthroat Trout are restricted primarily to headwater streams.
Habitat
Rio Grande cutthroat size is variable, and based on the available habitat. In small headwater streams adults are generally 6-10˝ in length
Diet
Rio Grande cutthroat primarily feed on aquatic and terrestrial insects, although at larger sizes they can be piscivorous, eating small fish
Reproduction
Rio Grande cutthroat spawn in the spring following runoff, when water temperatures approach 50° F. This takes place from March through July across their range.
Threats to Species
Nonnative Trout
Rainbow trout, an introduced species, as well as other cutthroat subspecies have the ability to hybridize with the Rio Grande cutthroat and therefore jeopardize genetic integrity at the population level. Other non-native trout, including brown trout and brook trout, threaten the Rio Grande cutthroat through competition for habitat and prey. To address the threats from non-natives, populations of Rio Grande cutthroat often require a physical separation in the form of a man-made or natural barrier. While these barriers are necessary, they can isolate populations and therefore make them more vulnerable to natural disturbances like wildfire and drought.
Roads, Logging, and Grazing
Cutthroat trout are sensitive to changes in water quality. Increased sedimentation created by roads, logging, and grazing can degrade spawning habitat. Decreases in concentrations of dissolved oxygen caused by higher stream temperatures and excessive nutrient inputs further restrict Rio Grande cutthroat distribution and reproductive success. Collaborative planning and management of these activities that account for healthy stream and riparian function is crucial to sustaining both RGCT populations and traditional resource use activities.
Mining and Irrigation
Mining and irrigation development can have negative impacts if improperly managed. With climate change predictions and an ongoing drought in the Southwest, the challenge is to reduce these negative impacts while sustaining agriculture and the local economies.
Additional Information
The first conservation agreement for Rio Grande Cutthroat Trout between state, federal, and tribal resource agencies was signed in 2003, giving rise to the Rio Grande Cutthroat Trout Conservation Team. The agreement's stated goal is to assure the "long-term viability of Rio Grande Cutthroat Trout throughout its historic range by minimizing or removing threats to the species and promoting conservation." This collaborative framework was updated in the 2013 Conservation Agreement and the 2013 Conservation Strategy, which outline long-term conservation objectives for this subspecies.
Conservation Team Documents
Status Assessments
- 2016 Status Assessment
- 2008 Status Assessment (27MB)
Conservation Strategies
- 2013 Conservation Strategy
- 2013 Conservation Agreement
Rangewide Accomplishments
- 2022 Rangewide Accomplishments
- 2021 Rangewide Accomplishments
- 2020 Rangewide Accomplishments
- 2019 Rangewide Accomplishments
- 2018 Rangewide Accomplishments
- 2017 Rangewide Accomplishments
- 2016 Rangewide Accomplishments
- 2015 Rangewide Accomplishments
- 2014 Rangewide Accomplishments
- 2013 Rangewide Accomplishments
- 2012 Rangewide Accomplishments
- 2011 Rangewide Accomplishments
- 2010 Rangewide Accomplishments
- 2009 Rangewide Accomplishments
- 2008 Rangewide Accomplishments