Cooperative Fish and Wildlife Research Units Program: Montana Fishery
Education, Research and Technical Assistance for Managing Our Natural Resources

Native populations of Westslope Cutthroat Trout (WCT) and Arctic Grayling in Yellowstone National Park were reduced or eliminated through competition, predation, and hybridization with nonnative fishes that were historically stocked by managers, ostensibly to enhance sportfishing. National Park Service fisheries managers carried out conservation actions aimed at restoring WCT and Arctic Grayling populations in two watersheds in Yellowstone National Park, including East Fork Specimen Creek in the Gallatin River drainage and Grayling Creek in the Madison River drainage. Conservation actions included 1) building barriers impassable to upstream fish movement to isolate watersheds; 2) applying rotenone, a lethal fish toxicant, to eliminate all fish from the watersheds above the barriers; and 3) reintroducing native fish to the isolated watersheds. NPS fisheries managers plan to continue restoration efforts of WCT and Arctic Grayling in additional park watersheds, but first want to understand how past conservation efforts performed to guide future restoration actions. Moreover, similar management actions are being conducted or contemplated worldwide. Therefore, the goal of this research project is to assess the recovery and status of the reintroduced populations of WCT and Arctic Grayling in East Fork Specimen and Grayling creeks. Our specific objectives are to 1) assess population abundance, size structure, condition, individual growth, and reproductive success of WCT and Arctic Grayling; 2) determine the spatial distributions of restored WCT and Arctic Grayling in relation to the reintroduction sites; 3) determine how population size structure and condition of recovering WCT in East Fork Specimen Creek compare to those of the hybridized WCT population they replaced; and 4) estimate the genetic population structure of recovering WCT relative to the contributions of the various WCT donor sources (Last Chance, Geode, and Muskrat creeks, and Sun Ranch Hatchery). Attainment of these objectives will provide fisheries managers with information needed to better manage such populations and to guide future restoration efforts elsewhere.