Life History Migrations of Adult Yellowstone Cutthroat Trout in the Upper Yellowstone River

Abstract

Knowledge of salmonid life history types at the watershed scale is increasingly recognized as a cornerstone for effective management. In this study, we used radiotelemetry to characterize the life history movements of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri in the upper Yellowstone River, an extensive tributary that composes nearly half of the drainage area of Yellowstone Lake. In Yellowstone Lake, Yellowstone Cutthroat Trout have precipitously declined over the past 2 decades primarily due to predation from introduced Lake Trout Salvelinus namaycush. Radio tags were implanted in 152 Yellowstone Cutthroat Trout, and their movements monitored over 3 years. Ninety-six percent of tagged trout exhibited a lacustrine–adfluvial life history, migrating upstream a mean distance of 42.6 km to spawn, spending an average of 24 d in the Yellowstone River before returning to Yellowstone Lake. Once in the lake, complex postspawning movements were observed. Only 4% of radio-tagged trout exhibited a fluvial or fluvial–adfluvial life history. Low prevalence of fluvial and fluvial–adfluvial life histories was unexpected given the large size of the upper river drainage. Study results improve understanding of life history diversity in potamodromous salmonids inhabiting relatively undisturbed watersheds and provide a baseline for monitoring Yellowstone Cutthroat Trout response to management actions in Yellowstone Lake.

Received July 21, 2016; accepted March 25, 2017 Published online June 12, 2017

ACKNOWLEDGMENTS

We thank Carter Kruse, Nicole Legere, Pat Bigelow, Steve Yekel, Bonnie Griffis, and many others for providing assistance with field work, logistics, and insight into conducting this project. We thank Andriana Puchany, Colleen Detjens, and two anonymous reviewers for providing insightful edits that improved our manuscript greatly. We would also like to thank the National Fish and Wildlife Foundation, Jackson Hole One Fly, and the Yellowstone Park Foundation for providing funding. We are indebted to the National Park Service and Wyoming Game and Fish Department for providing additional funding and personnel. Any use of trade, firm, or product names is strictly for descriptive purposes and is not an endorsement by the U.S. Government.