Native Fishes of the Northern Rockies

Native fish populations have declined drastically throughout western America over the past century as a consequence of habitat degradation and nonnative species introductions. Despite substantial activity in recent decades to protect remaining stocks and implement restoration activities, efforts are often hampered by the lack of comprehensive and integrated assessments of current resource status that are necessary to effectively integrate and prioritize management actions. For example, numerous federal and state resource management agencies and nongovernmental organizations have designated several subspecies of cutthroat trout and the riverine form of arctic grayling as a “species of special concern” or a “sensitive species.” Although management actions have improved the probability of persistence of the these taxa in some areas, recent invasions of nonnative species (e.g., lake trout, rainbow trout, New Zealand mud snail, and Myxobolus cerebralis - the causative agent of whirling disease), and continued drought in the Northern Rocky Mountains have caused increased concern. There is little doubt that observed and predicted changes in climate and the concomitant reduction in water resources will escalate conflicts among water users throughout the western USA, and these changes may further exacerbate effects of species invasions and habitat destruction on native fishes of the region.

Current Projects

• Destruction of lake trout embryos in natural settings to enhance persistence of native trout (Gresswell)
• Distribution, Abundance, and Movement of Native Cutthroat Trout in the Snake River below Jackson Lake (Gresswell)
• Evaluation of Habitat Restoration for the Fluvial Arctic Grayling in the Big Hole River, Montana (Gresswell)
• Influence of Invasive Lake Trout on Spawning Demographics and Early Life History of Bull Trout (Gresswell)
• A Technical Conservation Assessment of Yellowstone Cutthroat Trout (Gresswell)
• The role of demographic, genetic, and environmental factors influencing the spread of hybridization between native westslope cutthroat and non-native rainbow trout (Muhlfeld)
• Distribution, abundance and genetic diversity of bull trout and westslope cutthroat trout in Glacier National Park and the upper Flathead River system, Montana (USA) and British Columbia (Canada) (Muhlfeld): Implications for coal mining and coalbed methane development in the Crown of the Continent Ecosystem
• Preservation of bull trout in Glacier National Park: Experimental suppression of invasive lake trout in the Quartz Lake system (Muhlfeld)
• Evaluation of alternative dam operations on the movement and habitat use of bull trout and westslope cutthroat trout in the Flathead River (Muhlfeld)
• Risk-based monitoring and recovery of bull trout (Muhlfeld)
• Climate change impacts on native salmonids (Kershner, Muhlfeld, & Gresswell)

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