Theses and Dissertations at Montana State University (MSU)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/732
Browse
3 results
Search Results
Item Effects of stream temperature and climate change on fluvial arctic grayling and non-native salmonids in the upper Big Hole River, Montana(Montana State University - Bozeman, College of Letters & Science, 2015) Vatland, Shane Jeffrey; Chairperson, Graduate Committee: Alexander V. Zale; Robert E. Gresswell and Geoffrey C. Poole were co-authors of the article, 'Quantifying stream thermal regimes at management-pertinent scales: combining thermal infrared and stationary stream temperature data in a novel modeling framework' in the journal 'Water resources research' which is contained within this thesis.; Robert E. Gresswell, Steve Hostetler and Alexander V. Zale were co-authors of the article, 'Effects of climate change on the thermal habitats of arctic grayling and non-native stream salmonids' submitted to the journal 'Global change biology' which is contained within this thesis.The upper Big Hole River basin in southwestern Montana supports one of the last naturally-reproducing populations of fluvial Arctic grayling Thymallus arcticus in the coterminous United States. Warm summer water temperatures and negative interactions with non-native fish (brook trout Salvelinus fontinalis, rainbow trout Oncorhynchus mykiss, and brown trout Salmo trutta) have been identified as critical factors constraining this grayling population. Arctic grayling and these non-native fishes are all cold-water species with similar temperature requirements. Understanding when, where, and to what extent water temperatures are suitable for these fishes provides a physical basis for conservation planning. In chapter 2, I used a combination of thermal infrared (TIR) imagery and stationary temperature recorders to estimate water temperatures at a relatively fine spatial (every ~ 100 m of stream length) and temporal (continuous) resolution over a large extent of the Big Hole River (~ 100 km) during the warmest part of the summer in 2008. This modeling revealed considerable spatial and temporal heterogeneity in water temperature and highlighted the value of assessing thermal regimes at relatively fine spatial and temporal scales. In chapter 3, I assessed the potential effects of climate change on thermal suitability of summer water temperatures for these salmonids. Water temperature simulations projected significant warming from the 1980s through the 2060s. Despite this warming, water temperatures in some sections of stream remained below thermal tolerance thresholds through the 2060s. These stream temperature data provide a critical foundation for understanding the dynamic, multiscale habitat needs of these mobile stream fish and can aid in developing conservation strategies for fluvial Arctic grayling.Item Thermal adaptation of westslope cutthroat trout Oncorhynchus clarkii lewisi(Montana State University - Bozeman, College of Letters & Science, 2010) Drinan, Daniel P.; Chairperson, Graduate Committee: Alexander V. Zale; Molly A. H. Webb (co-chair)Understanding local adaptations is a fundamental goal of evolutionary biology and would provide managers information necessary to better protect and conserve species. Salmonids are a particularly useful system for studying local adaptations as they often persist in disparate and isolated environments. In addition, their sensitivity to temperature provides a likely candidate for natural selection to act. I studied thermal adaptation in four wild populations and one hatchery stock of westslope cutthroat trout. Native stream mean summer temperatures ranged from 6.7° to 11.2°C. Embryos were collected from the wild and differences in embryonic development, embryonic survival, and juvenile growth were measured. I found a significant relationship between median embryonic survival and native stream temperatures at warm incubation temperatures (Rank test; P = 0.04). The change in embryonic survival across incubation temperatures was consistent for populations from warm streams, but changed drastically for populations from cool streams. This difference suggests that populations from warmer streams may be thermal generalists, and populations from cooler streams may be thermal specialists. Results have both short- and long-term implications. In the short-term, managers should use these data to support the consideration of local adaptations when performing translocation projects. In the long-term, these data suggest that global climate change may be detrimental for westslope cutthroat trout.Item Effects of water temperature and angling on mortality of salmonids in Montana streams(Montana State University - Bozeman, College of Letters & Science, 2008) Boyd, J. W. (James W.); Chairperson, Graduate Committee: Christopher S. GuyIn Montana, angling closures are used to protect salmonids from the deleterious impacts of angling at elevated water temperatures (23°C). Catch-and-release angling (CR) studies have reported high levels (30-40%) of salmonid mortality at water temperatures >20°C, but few studies assess CR mortality of salmonids at water temperatures observed in Montana streams during mid-summer (23°C). The primary objective of this study was to measure CR mortality of rainbow trout, brown trout, and mountain whitefish in three water temperature treatments; when daily maximum water temperatures were cool (<20°C), warm (20 to 22.9°C), and hot (23°C). A secondary objective was to assess CR mortality of salmonids angled in morning and evening within water temperature treatments. Based on the literature, mortality of salmonids was predicted to be >30% within the hot treatment and higher in evening than morning. Angling (fly-fishing only) occurred in the Gallatin and Smith rivers. All angled fish were confined to in-stream holding cages and monitored for mortality for 72 h. Mortality of rainbow trout Oncorhynchus mykiss increased to 9% and 16% in warm and hot treatments, respectively. Mortality of brown trout Salmo trutta was (4%) in the hot treatment in the Smith River. Mountain whitefish Prosopium williamsoni had increased mortality in the warm (20%) and hot (28%) treatments in the Smith River. No mortality for any species occurred in either river when water temperatures were <20°C. Mortality of rainbow trout angled in evening was higher than morning in the warm (14%) and hot (16%) treatments in the Smith River. Laboratory results indicated rainbow trout stressed in evening had higher mortality (7%) than those stressed in morning (0%). Angler catch rates were lower for most species in evening than morning angling events; however, catch rates remained high (0.7 fish/h) in several evening angling events. Study results indicate that salmonid mortality rates associated with catch-and-release fly-fishing are higher at elevated (>or equal to 23°C) water temperatures. Although there was a relationship between elevated water temperature and salmonid mortality, most of the mortality estimates were well below the 30% mortality that was predicted.