Scholarly Work - Ecology
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8716
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Item Spatial and temporal variability of movements among sympatric salmonids in an unfragmented inland watershed(Wiley, 2024-08) Lance, Micahel J.; Ritter, T. David; Zale, Alexander V.; Grisak, Grant G.; Mullen, Jason A.; Walsh, Stephen J.; Heim, Kurt C.; Al-Chokhachy, RobertObjective. Our aim was to determine the movement patterns of three abundant salmonids—Brown Trout Salmo trutta, Mountain Whitefish Prosopium williamsoni, and Rainbow Trout Oncorhynchus mykiss—in the Smith River watershed of Montana. Methods. We tagged 7172 fish with passive integrated transponder (PIT) tags, monitored their movements past 15 stationary PIT arrays over 4 years, and located tagged fish between arrays by conducting mobile surveys. Result. Movement patterns varied seasonally, among species, and among locations. Movement was greatest in the middle portion of the watershed, which included a pristine main-stem canyon and lower reaches of major tributaries. Fish rarely left the canyon, but movement into the canyon from other regions was common. Mountain Whitefish were most likely to move, and Brown Trout were least likely to move. Most fish travelled less than 10 km, but some fish travelled over 100 km. Distinct movement patterns were not evident; rather, a continuous spectrum of movement behaviors was apparent. Movements by Mountain Whitefish and Rainbow Trout increased during their spawning periods. Movements peaked when mean daily water temperatures were between 11.3 and 17.1°C. Conclusion. Movements were diverse and probably contributed to metapopulation dynamics, population resiliency, and species diversity. Fish movements along stream networks connect populations across diverse landscapes, and therefore, protecting and restoring stream connectivity along inland streams such as the Smith River is critical to maintaining productive fish assemblages.Item Effects of Climate-Related Stream Factors on Patterns of Individual Summer Growth of Cutthroat Trout(2019-01) Uthe, Patrick R.; Al-Chokhachy, Robert; Shepard, Bradley B.; Zale, Alexander V.; Kershner, Jeff L.Coldwater fishes are sensitive to abiotic and biotic stream factors, which can be influenced by climate. Distributions of inland salmonids in North America have declined significantly, with many of the current strongholds located in small headwater systems that may serve as important refugia as climate change progresses. We investigated the effects of discharge, stream temperature, trout biomass, and food availability on summer growth of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri, a species of concern with significant ecological value. Individual size, stream discharge, sample section biomass, and temperature were all associated with growth, but had differing effects on energy allocation. Stream discharge had a positive relationship with growth rates in length and mass; greater rates of prey delivery at higher discharges probably enabled trout to accumulate reserve tissues in addition to structural growth. Temperature effects were positive but not significant, and support in growth models was limited, likely due to the cold thermal regimes of the study area. The strength of the discharge effect on growth suggests that climate adaptation strategies for coldwater fishes that focus solely on thermal characteristics may be misleading and highlights the importance of considering multiple factors, including hydrologic regimes, in conservation planning.