Theses and Dissertations at Montana State University (MSU)
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Item Use of eDNA to estimate abundances of spawning Yellowstone cutthroat trout in Yellowstone National Part, Wyoming, USA(Montana State University - Bozeman, College of Letters & Science, 2020) Detjens, Colleen Rachel; Chairperson, Graduate Committee: Alexander V. ZaleInvasive Lake Trout Salvelinus namaycush and whirling disease have reduced the abundance of native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri (YCT) in Yellowstone Lake, Yellowstone National Park, thereby disrupting the Yellowstone Lake ecosystem. One indication of the YCT population decline is the decrease in the number of adults returning to tributaries to spawn each spring. Yellowstone National Park implemented a gillnetting program to remove Lake Trout starting in 1995 to restore YCT abundance and size structure and thereby conserve the Yellowstone Lake ecosystem. An important metric for evaluating the success of the program is the number of YCT ascending spawning tributaries each year. Annually, 9 to 11 of these tributaries are visually surveyed on a weekly basis from May through July for the presence of spawners, but these surveys are time consuming. The use of environmental DNA (eDNA) has become increasingly common for determining presence of aquatic species and may provide managers with a more efficient tool for estimating abundances of YCT spawners. The primary objective of my study was to evaluate the efficacy and accuracy of using eDNA to detect the presence and estimate abundance of YCT spawners by collecting eDNA samples from spawning tributaries to Yellowstone Lake in conjunction with visual surveys of YCT spawners. A secondary objective was to evaluate whether terrestrial or semi-terrestrial species such as grizzly bear Ursus arctos horribilis and North American river otter Lontra canadensis could be detected in a water sample from YCT spawning tributaries. Environmental DNA quantities were more effective for determining presence of YCT spawners than for predicting their abundances, but eDNA quantities were positively related to spawner abundances. The difference between eDNA rates when spawners are present versus absent may provide managers with an efficient method for monitoring YCT in tributaries throughout Yellowstone Lake basin. I also demonstrated that DNA from a terrestrial species, grizzly bear, can be detected in water samples. Incorporation of eDNA sampling with existing methods for monitoring YCT spawners in Yellowstone Lake tributaries would facilitate an increased scale of assessment and allow for detection and quantification of multiple species of current and future interest from single samples.Item Use of otolith microchemistry to identify Yellowstone cutthroat trout and lake trout natal origins and movement patterns in Yellowstone Lake, Wyoming(Montana State University - Bozeman, College of Letters & Science, 2016) Stewart, Kole Patrick; Chairperson, Graduate Committee: Thomas E. McMahonThe Yellowstone Lake Yellowstone cutthroat trout population has declined as a result of drought, whirling disease, and the introduction of lake trout. Little is known about the recruitment patterns of cutthroat trout and lake trout in this system. Otolith microchemistry is uniquely suited for answering these questions by matching the chemical signatures found in otoliths to the same signatures found in the water fish occupy. My first objective was to identify and compare the primary spawning streams contributing to historic (1997) and recent (2013) cutthroat trout recruitment. I analyzed the chemical signatures (87 Sr:86 Sr, Sr:Ca, Ba:Ca, Mg:Ca, and Mn:Ca) of 22 cutthroat trout spawning streams and the same signatures from the natal region of cutthroat trout otoliths. There was low variation among the chemical signatures of many spawning streams, thus streams were grouped into 9 clusters using a cluster analysis. Relative recruitment to each cluster was assessed using random forest models with a classification accuracy of 84.4% for known-origin cutthroat trout fry otoliths and 79.0% for simulated otolith signatures. There was a significant difference in the proportions of recruitment between historic and recent cutthroat trout spawning clusters (X 2 = 15.40, p = 0.03). The majority of historic (0.84) and recent (0.77) recruitment occurred in the same three stream clusters, with the most notable change being a decrease in recent recruitment in the stream cluster containing Pelican Creek and an increase in recruitment in tributaries in the upper Yellowstone River drainage. The second objective was to identify the spawning locations and movement patterns of lake trout within Yellowstone Lake. I analyzed the 87 Sr:86 Sr, and Sr:Ca signatures from 8 locations throughout Yellowstone Lake and the same signatures in 20 lake trout otoliths. I did not find sufficient variation within the lake water chemistry to differentiate lake regions and there was no significant differences found within in the lake trout otolith transects. This study can be used to inform future spawning stream conservation and restoration by directing managers towards spawning streams of increasing or decreasing importance. This study also highlights some of the strengths and limitations of using microchemistry studies in freshwater system.Item Spawning and early life history of mountain whitefish in the Madison River, Montana(Montana State University - Bozeman, College of Letters & Science, 2016) Boyer, Jan Katherine; Chairperson, Graduate Committee: Christopher S. Guy; Christopher Guy, Molly Webb, Travis Horton and Thomas McMahon were co-authors of the article, 'Spawning behavior and juvenile distribution of mountain whitefish in the Madison River, Montana' submitted to the journal 'Transactions of the American Fisheries Society' which is contained within this thesis.; Christopher Guy, Molly Webb, Travis Horton and Thomas McMahon were co-authors of the article, 'Gear comparison for sampling age-0 mountain whitefish' submitted to the journal 'North American journal of fisheries management' which is contained within this thesis.Mountain Whitefish were historically common throughout much of the Intermountain West. However, within the last decade Mountain Whitefish have exhibited population-level declines in some rivers. In the Madison River, Montana, anecdotal evidence indicates Mountain Whitefish abundance has declined and the population is skewed toward larger individuals, which is typically symptomatic of recruitment problems. Recruitment is influenced by factors including reproductive development, spawning behavior, and juvenile distribution. Describing these factors and identifying efficient methods for sampling age-0 fish would form a foundation for investigating mechanisms influencing recruitment. I collected otoliths and gonad samples (n = 147) to characterize fecundity, age-at-maturity, and spawning periodicity. I implanted radio tags in mature Mountain Whitefish (n = 138) and relocated tagged fish in autumn 2012 - 2014. Timing of spawning was determined from spawning status of captured females (n = 85) and from density of eggs collected on egg mats. In spring 2013, I evaluated backpack electrofishing, seining, minnow traps, and lighted minnow traps at sampling sites downstream of Varney Bridge (n = 92). In spring 2014, I seined backwater and channel sites (n = 221) to describe age-0 distribution. Mountain Whitefish in the Madison River were highly fecund (18,450 eggs/kg body weight) annual spawners, and age at 50% maturity was 2.0 for males and 2.6 for females. In 2013 and 2014, spawning occurred between the third week of October and first week of November. Movement varied as a function of spawning behavior, and prespawning movements trended downstream. During spawning, spawning adults and collected embryos were concentrated in the downstream 26 km of the study site, a reach characterized by a complex, braided channel. Of the gears tested, seines were most efficient at sampling age-0 Mountain Whitefish. The downstream reach had the highest catch-per-unit effort of age-0 Mountain Whitefish. Within this reach, age-0 fish were associated with silt-laden backwater and eddy habitats. Maturation and fecundity were similar to other populations, and reproductive development appeared normal, thus factors influencing recruitment probably occur post spawning. Spawning and age-0 rearing sites were concentrated in a small area, thus future work should investigate stressors present in incubation and rearing areas.