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Dona Horan

Fish Biologist

322 East Front Street, Suite 401
Boise, ID 83702
Contact Dona Horan

Current Research

  • Helping to develop basinscale stream temperature models using ArcGIS and spatial statistical models
  • Developing documentation to assist resource managers to create stream temperature statistical models in their management areas
  • Creating a regional network of ongoing, annual temperature monitoring sites
  • Developing simple, cost-effective methods for deploying long-term stream temperature loggers

Research Interests

I am interested in studying the factors that influence fish distribution and persistence. I am curious about the effects of climate change on fish movement and habitat quality, and how the models we're currently developing will reflect what happens in the region's streams over the next few decades. I enjoy helping and supporting resource managers in their development of long-term temperature monitoring networks and stream temperature models.

Past Research

Fish biology and behavior, as well as the study of habitat quality, are very complex issues. While many attributes have been studied in an attempt to define high-quality fish habitat, stream temperature may be one of the biggest factors influencing their survival.

Why This Research is Important

  • Studied fish migration using otolith microchemistry
  • Studied effects of fire on fish abundance and distribution


  • University of California, Berkeley, B.S., Wildlife Management, 1992
  • Utah State University, M.S., Fisheries Management, 1996
  • Featured Publications


    Isaak, Daniel J.; Luce, Charles H.; Horan, Dona; Chandler, Gwynne L.; Wollrab, Sherry P.; Dubois, William B.; Nagel, David E., 2020. Thermal regimes of perennial rivers and streams in the western United States
    Young, Michael K.; Isaak, Daniel J.; Spaulding, Scott; Thomas, Cameron A.; Barndt, Scott A.; Groce, Matthew C.; Horan, Dona; Nagel, David E., 2018. Climate vulnerability of native cold-water salmonids in the Northern Rockies Region [Chapter 5]
    Isaak, Daniel J.; Young, Michael K.; Tait, Cynthia; Duffield, Daniel; Horan, Dona; Nagel, David E.; Groce, Matthew C., 2018. Effects of climate change on native fish and other aquatic species [Chapter 5]
    Wilcox, Taylor M.; Young, Michael K.; McKelvey, Kevin S.; Isaak, Daniel J.; Horan, Dona; Schwartz, Michael K., 2018. Fine-scale environmental DNA sampling reveals climate-mediated interactions between native and invasive trout species
    Isaak, Daniel J.; Luce, Charles H.; Horan, Dona; Chandler, Gwynne L.; Wollrab, Sherry P.; Nagel, David E., 2018. Global warming of salmon and trout rivers in the northwestern U.S.: Road to ruin or path through purgatory?
    Isaak, Daniel J.; Luce, Charles H.; Chandler, Gwynne L.; Horan, Dona; Wollrab, Sherry P., 2018. Principal components of thermal regimes in mountain river networks
    Isaak, Daniel J.; Ramsey, Katherine; Chatel, John C.; Konnoff, Deborah L.; Gecy, Robert A.; Horan, Dona, 2017. Climate change, fish, and aquatic habitat in the Blue Mountains [Chapter 5]
    Young, Michael K.; Isaak, Daniel J.; McKelvey, Kevin S.; Wilcox, Taylor M.; Campbell, Matthew R.; Corsi, Matthew P.; Horan, Dona; Schwartz, Michael K., 2017. Ecological segregation moderates a climactic conclusion to trout hybridization
    Isaak, Daniel J.; Wenger, Seth J.; Peterson, Erin E.; Ver Hoef, Jay M.; Nagel, David E.; Luce, Charles H.; Hostetler, Steven W.; Dunham, Jason B.; Roper, Brett B.; Wollrab, Sherry P.; Chandler, Gwynne L.; Horan, Dona; Payne (Parkes) , Sharon L., 2017. The NorWeST summer stream temperature model and scenarios for the western U.S.: A crowd-sourced database and new geospatial tools foster a user community and predict broad climate warming of rivers and streams
    Young, Michael K.; Isaak, Daniel J.; McKelvey, Kevin S.; Wilcox, Taylor M.; Bingham, Daniel M.; Pilgrim, Kristine L.; Carim, Kellie; Campbell, Matthew R.; Corsi, Matthew P.; Horan, Dona; Nagel, David E.; Schwartz, Michael K., 2016. Climate, demography, and zoogeography predict introgression thresholds in salmonid hybrid zones in Rocky Mountain streams
    Isaak, Daniel J.; Young, Michael K.; Luce, Charles H.; Hostetler, Steven W.; Wenger, Seth J.; Peterson, Erin E.; Ver Hoef, Jay M.; Groce, Matthew C.; Horan, Dona; Nagel, David E., 2016. Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity
    Isaak, Daniel J.; Young, Michael K.; Nagel, David E.; Horan, Dona; Groce, Matthew C., 2015. The cold-water climate shield: Delineating refugia for preserving salmonid fishes through the 21st century
    Isaak, Daniel J.; Young, Michael K.; Nagel, David E.; Horan, Dona, 2014. Cold water as a climate shield to preserve native trout through the 21st Century
    Peterson, Douglas P.; Rieman, Bruce E.; Horan, Dona; Young, Michael K., 2014. Patch size but not short-term isolation influences occurrence of westslope cutthroat trout above human-made barriers
    Wenger, Seth J.; Isaak, Daniel J.; Dunham, Jason B.; Fausch, Kurt D.; Luce, Charles H.; Neville, Helen M.; Rieman, Bruce E.; Young, Michael K.; Nagel, David E.; Horan, Dona; Chandler, Gwynne L., 2011. Role of climate and invasive species in structuring trout distributions in the interior Columbia River Basin, USA
    fishing on snake river
    Anyone familiar with the Columbia River’s massive salmon die-off a few summers ago might also be concerned about how climate change will affect fish habitats. The 2015 die-off killed more than 250,000 fish and was blamed on record low streamflows and high water temperatures. While coldwater fish such as salmon and trout can adjust to slightly warmer-than-normal temperatures for short periods, abnormally high temperatures for prolonged periods lower oxygen levels, increase the likelihood of deadly diseases, and cause life-threatening physiological stress.
    Westslope cutthroat trout, native to the Columbia River and upper Missouri River hybridize with introduced rainbow trout and have been extirpated from large portions of their historical range.
    Hybridization between westslope cutthroat trout and both rainbow trout and Yellowstone cutthroat trout is a major conservation concern for the species.  A new broad-scale analysis of hybridization patterns found many pure populations of westslope cutthroat trout in headwaters streams.
    The website provides: 1) A large list of supporting science behind eDNA sampling. 2) The recommended field protocol for eDNA sampling and the equipment loan program administered by the NGC. 3) A systematically-spaced sampling grid for all flowing waters of the U.S. in a downloadable format that includes unique database identifiers and geographic coordinates for all sampling sites. Available for download in an Geodatabase or available by ArcGIS Online map. This sampling grid can be used to determine your field collection sites to contribute. 4) The lab results of eDNA sampling at those sites where project partners have agreed to share data.
    Flow gages* record discharge in streams and rivers across the U.S. but the extent and adequacy of this monitoring network relative to USFS lands has not been documented. To address that deficiency, the medium resolution National Hydrography Layer was used with gage location information from the National Water Information System to describe the monitoring network and how it has changed through time. Summaries were made for eight USFS regions that describe the number and locations of gages relative to USFS lands and network characteristics such as elevation and watershed area.
    Spatial statistical models for streams provide a new set of analytical tools that can be used to improve predictions of physical, chemical, and biological characteristics on stream networks. The Spatial Tools for the Analysis of River Systems (STARS) and Spatial Stream Network (SSN) models are unique because they account for patterns of spatial autocorrelation among locations based on both Euclidean and in-stream distances
    Thermal regimes are important to aquatic ecosystems because they strongly dictate species distributions, productivity, and abundance. The stream temperature modeling and monitoring web site provides resources to help those in the western United States organize temperature monitoring efforts, describes techniques for measuring stream temperatures, and describes several statistical models for predicting stream temperatures and thermally suitable fish habitats from temperature data.

    RMRS Science Program Areas: 
    Air, Water and Aquatic Environments