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Item Mechanisms of rainbow trout hybridization with native cutthroat trout in the Lamar River of Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2019) Heim, Kurt Conrad; Chairperson, Graduate Committee: Thomas E. McMahon; Thomas E. McMahon, Clint C. Muhlfeld, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Interspecific hybridization solves a phenological breeding mismatch for a nonnative invader' submitted to the journal 'Ecology' which is contained within this dissertation.; Thomas E. McMahon, Steven T. Kalinowski, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Invasive hybridization in a high-elevation stronghold: genetic status of Yellowstone cutthroat trout in the Lamar River of Yellowstone National Park' submitted to the journal 'Canadian journal of fisheries and aquatic sciences' which is contained within this dissertation.; Thomas E. McMahon, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Leveraging public harvest for genetic management: identification and exploitation of invasive hybrid trout in Yellowstone National Park' submitted to the journal 'Biological invasions' which is contained within this dissertation.Invasive hybridization--when invasive species interbreed with native species--is a pervasive conservation issue. Hybridization presents difficult management decisions and poses complex problems at the intersection of contemporary evolution, invasion biology, physiology, and landscape ecology. I examined the invasion scenario playing out in the Lamar River watershed of Yellowstone National Park where native Yellowstone cutthroat trout (YCT) are undergoing hybridization with introduced rainbow trout (RT). I first test the hypothesis that a breeding timing mismatch of an invasive species (i.e., RT often spawn far earlier than YCT, and eggs are scoured by snowmelt runoff) can be overcome by hybridization with a locally adapted native species, that spawn later (Chapter 2). I found support for this hypothesis. Spawning timing was strongly related to the degree of non-native admixture at the individual level, indicating that hybridization alters breeding timing in ways that could benefit hybrids. At the population level, hybrid spawning timing closely matched that of native taxa and was strongly correlated to stream flow conditions. Overall, these data suggest poorly matched spawning timing is unlikely to serve as a strong mechanism limiting invasive hybridization of YCT. Next, I mapped the spatial distribution of hybridization in the Lamar River watershed (Chapter 3). Many non-hybridized populations persist in the upper watershed, whereas a prominent source of RT in the lower watershed has likely contributed inordinately to the spread of introgression. Because hybridized populations occurred across a full range of environmental conditions, I do not predict that abiotic conditions (i.e., cold water, late-stream flow, high elevations, or small stream size) will prevent the spread of hybridization in the long-term. As such, management interventions are recommended in chapter 4 and 5. I developed a simple taxonomic key to identify hybrids and guide selective removal efforts (Chapter 4). Additionally, I used volunteer angler surveys to estimate that recreational anglers visiting the watershed (~10,000 per year) could likely harvest a substantial number of non-native trout that would contribute to genetic management goals. I conclude by providing recommendations for management and monitoring (Chapter 5).Item Feasibility of walleye population suppression in Buffalo Bill Reservoir, Wyoming(Montana State University - Bozeman, College of Letters & Science, 2019) Kaus, Daniel Joseph; Chairperson, Graduate Committee: Christopher S. GuyBuffalo Bill Reservoir, Wyoming is managed as a wild Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout Oncorhynchus clarkii fishery. Nonnative Walleyes Sander vitreus were discovered in 2008, and spring sampling of Walleye indicate natural recruitment and a rapidly expanding population. Walleyes pose a predation threat to the wild trout populations in Buffalo Bill Reservoir. The Wyoming Game and Fish Department (WGFD) is interested in suppressing the Walleye population using mechanical removal with electrofishing and gillnetting during the Walleye spawning period. The purpose of this study was to evaluate the population demographics of Walleyes in Buffalo Bill Reservoir. Age-structured population models were used to estimate the Walleye population growth rate for scenarios with and without Walleye removal. To inform the population models, age-specific fecundity, probability of maturity, natural mortality, and fishing mortality were estimated. Mean asymptotic population growth rate for the five scenarios were estimated as 1.22 (95% CI of 1.05 to 1.37) for no suppression, 1.18 (95% CI of 1.04 to 1.32) for electrofish exploitation, 1.04 (95% CI of 0.88 to 1.19) for gill-net exploitation, 0.91 (95% CI of 0.61 to 1.36) for angler exploitation, and 0.81 (95% CI of 0.66 to 0.96) for angler and gill-net exploitation combined. Results from the age-structured population models suggest that long-term population suppression is a viable goal, and additional gill-net effort and angler harvest incentives should be pursued. During this study the density of mature Walleyes was low, indicating that the population had not yet reached carrying capacity. Analysis of population inertia indicates that the projected abundance of the initial population vector results in a lower population size compared to projected abundance of a population with stable-age distribution. Results from this study will be used to inform cost-effective management decisions regarding the future of the recreational fishery in Buffalo Bill Reservoir. The cost per mature female removed in 2017 was $490.91 and $80.08 for electrofish and gill net removal, respectively. Future suppression efforts should be monitored using population indices of age diversity for female Walleyes.Item Spatial and temporal variability in movements and vital rates of sympatric salmonids in an unfragmented, inland watershed(Montana State University - Bozeman, College of Letters & Science, 2019) Lance, Michael James; Chairperson, Graduate Committee: Alexander V. ZaleThe life history patterns and vital rates of stream dwelling fish can differ across biological, spatial, and temporal scales. We determined the movement patterns and vital rates of three abundant salmonids--brown trout (Salmo trutta), mountain whitefish (Prosopium williamsoni), and rainbow trout (Oncorhynchus mykiss)--in the Smith River watershed of Montana, a system with three distinct geomorphic regions: the headwaters, semi-wilderness canyon, and prairie. We marked 7,172 fish with passive integrated transponder (PIT) tags, monitored their watershed-scale movements past 15 stationary PIT arrays over four years, and relocated fish between arrays by conducting mobile surveys along the Smith River and major tributaries. Fish movement patterns and survival probabilities varied seasonally, among species, and among locations within the watershed. Volume of movement and diversity of movers were both greatest in the canyon region and in lower portions of tributaries. Fish rarely left the canyon, but movement into the canyon from other regions was common among some groups of fish. Mountain whitefish were most likely to move and brown trout were least likely to move. The stream lengths traversed by fish followed a leptokurtic distribution with most fish travelling < 10 km and decreasing numbers of fish travelling farther. Distinct life history patterns were not evident as judged by the stream lengths traversed by tagged fish; rather, a continuous spectrum of distances traversed was apparent. Species-specific spawning periods were associated with increased frequency of movement by mountain whitefish and rainbow trout. Increases in the frequency of watershed-scale movements of all three species were associated mean daily water temperatures of 11.7-15.3°C, compared to periods when water temperatures were cooler or warmer. Annual probabilities of survival were highest among mountain whitefish (0.38-0.54) and lower among brown trout (0.16-0.38) and rainbow trout (0.08-0.39). Survival of rainbow trout and mountain whitefish was highest in the canyon. Survival of mountain whitefish was also high in the headwaters but was lowest in the prairie. Movements of fish in the Smith River watershed were diverse, allowed movement among habitats with different probabilities of survival, and probably contributed to meta-population function, population resiliency, and species diversity.Item Effects of prolonged exposure to ammonia on rainbow trout (Salmo gairdneri) eggs and sac fry(Montana State University - Bozeman, College of Agriculture, 1975) Burkhalter, Dalton EarlItem Comparative genetics of rainbow trout from the geothermally heated Firehole River, Wyoming(Montana State University - Bozeman, College of Agriculture, 1980) Fisher, Paul WayneItem Electrophoretic patterns of blood serum proteins from rainbow trout (Salmo gairdneri)(Montana State University - Bozeman, College of Agriculture, 1966) Thurston, Robert VanceItem Genetic variation in the rainbow trout population in the Firehole River(Montana State University - Bozeman, College of Agriculture, 1978) Browne, David LawrenceItem Factors affecting the resistance of juvenile rainbow trout to whirling disease(Montana State University - Bozeman, College of Letters & Science, 2003) Ryce, Eileen Karpoff NicolItem The migration of Cotylurus erraticus cercariae (Trematoda: Strigeidae) in rainbow trout (Salmo gairdneri) and their effects on the host(Montana State University - Bozeman, College of Agriculture, 1968) Johnson, Keith AlanItem Condition, annulus formation, growth, and food habits of brown and rainbow trout from habitats with contrasting temperature regimes on the Firehole River, Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 1976) Kaeding, Lynn Robert