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New Genetic Tool Highlights Bull Trout Distribution

Posted date: February 09, 2016

Study finds bull trout in new places



New Genetic Tool Highlights Bull Trout Distribution


Missoula, Mont., Feb 9, 2016 – New research out of the National Genomics Center for Wildlife and Fish Conservation at the U.S. Forest Service Rocky Mountain Research Station found environmental DNA to be an effective tool for monitoring fish species across their range and that bull trout exist in some streams where biologists thought they had been lost.

This study, released in the Journal of Fish Biology, evaluated new technologies using environmental DNA to assess whether this cost-effective method could be applied to successfully monitor the presence of bull trout in western Montana. This is one of the first papers to demonstrate the utility of eDNA for delineating a species’ range across broad landscapes. 

The iconic bull trout was listed as "threatened" by the U.S. Fish and Wildlife Service in 1998. Bull trout can grow very large, have long life spans and often travel significant distances. They require very cold water and specific habitat elements, like clean rock substrate, for spawning and rearing. Understanding where this fish is currently in existence is critically important for conservation efforts. This paper shows that in the sampled western Montana rivers, at least a few bull trout are persisting in some stream reaches where biologists had considered them lost.

Male bull trout in the East Fork Bitterroot River Basin. Aubree Benson, Forest Service
Male bull trout in the East Fork Bitterroot River Basin. Aubree Benson, Forest Service

Rapidly and accurately determining species presence (particularly for a federally listed species) is of great utility for management. Monitoring for fish like the bull trout has traditionally occurred using methods such as electrofishing and snorkeling. These more traditional methods are expensive both in terms of the time and resources it takes to sample across a species’ range. Aquatic monitoring using eDNA is relatively cheap, takes a fraction of the time as other methods, and collecting samples is so simple that nearly anyone can do it. Finally, as this study showed, eDNA has as much accuracy as traditional methods.

“eDNA is a great complement and in some cases an alternative to traditional sampling methods such as electrofishing,” said Scott Spaulding, project collaborator and Regional Fisheries Program Leader for the U.S. Forest Service Northern Region. “It provides an efficient and accurate way to conduct broad-scale or site-specific inventories of fish important to managers. This helps set the stage for monitoring changes over time and it can help a program efficiently identify streams where biologists should further investigate fish populations using other techniques.”


Related Publications

McKelvey, Kevin S. ; Young, Michael K. ; Knotek, W. L. ; Carim, Kellie ; Wilcox, T. M. ; Padgett-Stewart, T. M. ; Schwartz, Michael K. , 2016

The Rocky Mountain Research Station (RMRS) is one of seven units within the U.S. Forest Service Research and Development. RMRS maintains 14 field laboratories throughout a 12-state territory encompassing parts of the Great Basin, Southwest, Rocky Mountains, and the Great Plains. RMRS also administers and conducts research on 14 experimental forests, ranges and watersheds and maintains long-term research databases for these areas. While anchored in the geography of the West our research is global in scale. To find out more about the RMRS go to You can also follow us on Twitter at




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National Strategic Program Areas: 
Wildlife and Fish
National Priority Research Areas: 
Localized Needs
RMRS Science Program Areas: 
Wildlife and Terrestrial Ecosystems
RMRS Strategic Priorities: 
Species Endangerment
bull trout; eDNA; Montana
Jennifer Hayes
Public Affairs Specialist