New paper
Will Rosenthal, Robert Al-Chokhachy, Matt Campbell, Katie Wager, Annika Walters, and I recently published a paper entitled Riverscape heterogeneity shapes population diversity for a migratory fish in Ecological Applications. The paper is available open access here: https://doi.org/10.1002/eap.70247.
We used genetic stock identification (GSI) to quantify the contribution of individual tributary streams to the mainstem Snake River population of Yellowstone cutthroat trout. Here are some key findings:
- 94% of adult trout in the mainstem Snake River originated from tributary streams.
- The composition of the mainstem population varied spatially from upstream to downstream. For example, Upper Bar BC, Blacktail Springs, and Cottonwood Creek dominated contributions to mainstem sections within Grand Teton National Park; Fish Creek and Lower Bar BC dominated in the sections near the town of Jackson, WY; and Willow, Cabin, and Bailey Creeks dominated in downstream sections.
- Closer and larger tributaries with greater groundwater availability increased contributions to the mainstem, while natural and anthropogenic barriers to fish passage reduced contributions.
Our results show that diverse assemblages of tributary streams are critical for sustaining trout populations in the Snake River. While spring-fed streams contributed disproportionately relative to their size, the lower river depended on snowmelt-dominated streams with very different habitat characteristics. We also demonstrate how GSI can be used for conservation and management applications. For example, GSI could be used to expand the coverage of mark-recapture population estimates by detecting and partitioning contributions from unmonitored tributaries. In addition, GSI could be used to detect the reemergence of migratory life histories following the removal of fish passage barriers.
This work was funded by the Jackson Hole One Fly Foundation; Wyoming Wildlife and Natural Resource Trust; Grand Teton Association Boyd Evison Fellowship; the Biodiversity Institute, Department of Zoology and Physiology, Wyoming Cooperative Fish and Wildlife Research Unit, and the Wy-ACT project at the University of Wyoming; and the UW-NPS AMK Research Station. We would also like to thank the many individuals who provided in-kind support, in particular the Wyoming Game and Fish Department.