Cooperative Research Units
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Yellowstone cutthroat trout hybridization in the North Fork Shoshone River


July 2016 - June 2019


The Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri has experienced substantial declines in abundance and distribution. Yellowstone cutthroat trout occupies 42% of its historic range, but only 28% of populations are genetically unaltered. Hybridization with rainbow trout Oncorhynchus mykiss may present the greatest threat to conservation of YSC. Introgression from RBT may lead to the breakdown of important local adaptations in native cutthroat trout subspecies, and lead to loss of fitness of these subspecies in their native habitats, the formation of hybrid swarms, and genetic extinction of pure cutthroat trout. This project is in collaboration with Wyoming Game and Fish Department and U.S. Forest Service. The goal is to determine the extent of hybridization within the North Fork Shoshone River drainage and evaluate the relationship between hybridization and environmental variables (e.g., temperature, discharge, slope). This will allow managers to identify priority tributaries and determine conservation potential of Yellowstone cutthroat trout in the North Fork Shoshone River drainage.


Current Staff

Federal Staff: 95

Masters Students: 240

Phd Students: 142

Post Docs: 52

University Staff: 242

5 Year Summary

Students graduated: 702

Scientific Publications: 1951

Presentations: 4266



Funding Agencies

  • USDA Forest Service
  • Wyoming Game & Fish Department
  • Wyoming Game and Fish Department
  • Wyoming INBRE


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey