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The Effects of Drought on Rio Grande Cutthroat Trout: The Role of Stream Flow and Temperature

Principal Investigator
Colleen Caldwell


Start Date
End Date
Release Date


Increasing temperatures and decreasing precipitation threaten the persistence of the Rio Grande cutthroat trout, the southernmost subspecies of cutthroat trout, found only in parts of New Mexico and Colorado. This subspecies appears to be more vulnerable to drought than more northern subspecies, because it occupies small and fragmented streams which are at greater risk of drying up during drought. Most notably, in 2002 drought in the Southwest resulted in the loss of 14 different Rio Grande cutthroat trout populations – about 10% of the total population. While it is known that drought is having an effect on Rio Grande cutthroat trout, the specific ways in which individuals and populations are affected by drought remains unclear. [...]

Child Items (4)


Principal Investigator :
Colleen Caldwell, Brock Huntsman
Co-Investigator :
Abigail J Lynch
Funding Agency :
CMS Group :
Climate Adaptation Science Centers (CASC) Program

Attached Files

Click on title to download individual files attached to this item.

“Rio Grande cutthroat trout - Credit: Craig Young”
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“Measuring a Rio Grande Cutthroat Trout (photo: A. Lynch, USGS)”
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“Electrofishing (Photo: A. Lynch, USGS)”
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“Pit-tagging a Rio Grande Cutthroat Trout (Photo: A. Lynch)”
7.34 MB video/quicktime
“Pit-tagging a Rio Grande Cutthroat Trout (Photo: A. Lynch)”
11.74 MB video/quicktime
“Stomach contents of a Rio Grande Cutthroat Trout (Photo: A. Lynch, USGS)”
21.21 MB video/quicktime
“Biologist A. Lynch & a Rio Grande Cutthroat Trout (photo: B. Huntsman, NMSU)”
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“Setting a drift net (Photo: A. Lynch, USGS)”
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“Electrofishing (Photo: A. Lynch, USGS)”
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“Stream - Public Domain”
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“Graduate student, Lauren Flynn with Rio Grande Cutthroat (Photo: E. Leipold)”
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“Rio Grande Cutthroat in diet of Rio Grande Cutthroat (Photo: E. Leipold)”
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“Rio Grande Cutthroat gastric lavage (Photo: E. Leipold)”
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Leipold_photo_release_form.pdf 56.06 KB application/pdf


Although Rio Grande cutthroat trout are not currently considered at immediate risk of extinction (recent 12-month finding by the U.S. Fish and Wildlife Service determined listing under the Endangered Species Act was not warranted; U.S. Federal Register 2014), climate perturbations such as increasing air temperatures and drought are expected to have significant impacts on the persistence of the subspecies. Increases in air temperature and decreases in precipitation will increase aridity across the subspecies’ current range and increase the duration and severity of droughts. In 2002, for example, drought conditions throughout the southwestern U.S. extirpated 14 Rio Grande cutthroat trout populations. Nearly ten years later (2011-2012), the southwest experienced the worst drought on record with ‘exceptional’ drought conditions lasting well over 350 days. These climate shifts will likely affect Rio Grande cutthroat trout differently than northern subspecies of cutthroat trout. This is primarily because this southern subspecies occupy small isolated habitat patches with low flow and frequent intermittency in comparison to northern subspecies (i.e., Yellowstone and westslope cutthroat trout) which occupy large river systems and lakes. Our research will characterize the effects that low flow conditions related to drought affect the health and long term persistence of a southwestern native cutthroat trout. Through this research, we will recommend management alternatives that might increase the likelihood of populations surviving drought conditions. These could include increasing connectivity of habitat to increase opportunity for fish to move away from areas that go intermittent.

Project Extension

typeTechnical Summary
valueRio Grande cutthroat trout Oncorhynchus clarkii virginalis are the southernmost subspecies of cutthroat trout and currently occupy only 12% of their historic range. Loss of habitat due to competition and hybridization with introduced trout and habitat alteration has restricted the remaining 122 populations to small (5.8 km median length) isolated habitat patches. A recent stream temperature and discharge monitoring program also identified that the majority of occupied habitat patches, while currently thermally suitable for the subspecies, have very low summer baseflows (< 1.0 cfs). Low baseflows during the summer restrict movement of fish in these small populations and increases the risk of population extirpation due to stochastic disturbances (i.e. drought). The primary goal of this study is to assess the likelihood of and projected impacts of drought on selected Rio Grande cutthroat trout populations through decreases in stream flow and increases in stream temperature. Specific study objectives will be to: 1) empirically assess the effects of seasonal stream temperature and discharge on the population vital rates for select Rio Grande cutthroat trout populations considered at risk during drought conditions; and 2) model drought effects on the persistence of Rio Grande cutthroat trout populations. The second objective includes two sub-objectives: a) model stream discharge, intermittency, and temperature in occupied Rio Grande cutthroat trout streams under drought conditions and b) evaluate how drought conditions will alter population vital rates and persistence of these populations.
projectStatusIn Progress

Budget Extension

typeAgreement Type
typeAgreement Number

Stream - Public Domain
Stream - Public Domain


Spatial Services

ScienceBase WMS


  • National CASC
  • National and Regional Climate Adaptation Science Centers

Associated Items



Additional Information


Type Scheme Key
RegistrationUUID NCCWSC c6c86e5f-239d-4562-baa1-6cef2081cf31

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