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Jaws: a love story
(Montana State University - Bozeman, College of Arts & Architecture, 2024) Kemp, Morgan Markley; Chairperson, Graduate Committee: Jim Zimpel
Approximately 100 million sharks are killed per year due to finning, fishing, and beauty industries. The destruction of a critical apex predator has been overlooked due to a lack of empathy for the venerable creature. This is due to the negative impacts from the film Jaws and the subsequent rise in fear mongering media that has created a false persona that sharks are blood-thirsty man-eating monsters meant to be feared and worthy of defeat. In order to generate positive change to save sharks, the populations perception of what sharks are must be changed. By creating a body of artwork inspired by the true beauty of sharks, fearful opinions of sharks can be exchanged for respect and admiration. Subtilities of the atrocities afflicting sharks can be introduced in a palatable way resulting in empathy that can enact real change for shark conservation.
Assessment of the Yellowstone Lake food web during lake trout suppression and Yellowstone cutthroat trout recovery informs conservation benchmarks
(Montana State University - Bozeman, College of Letters & Science, 2022) Glassic, Hayley Corrine; Chairperson, Graduate Committee: Christopher S. Guy; This is a manuscript style paper that includes co-authored chapters.
The collapse of native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri (hereafter cutthroat trout) in Yellowstone Lake was caused by predation by invasive lake trout Salvelinus namaycush. As an ecosystem with a low-diversity fish assemblage and several longterm data sets, Yellowstone Lake provided a unique opportunity to evaluate the influence of an invasive salmonid population undergoing suppression beyond only predator-prey dynamics. Diet data for cutthroat trout and lake trout were evaluated at varying densities to determine the effects of density on diet composition and diet plasticity. During the lake trout high-density state, lake trout consumed fewer native cutthroat trout and switched to amphipods, which were also consumed by cutthroat trout, resulting in high diet overlap between the species. As suppression reduced invasive lake trout densities, lake trout returned to consuming cutthroat trout and diet overlap was released. A shift in lake trout delta 13C signatures from the high-density state to the moderate-density state also corroborates higher consumption of cutthroat trout and invasive lake trout diet plasticity. Beyond predator-prey dynamics of lake trout and cutthroat trout, the invasion of lake trout caused > or = 25% change in energy flux for all organisms in Yellowstone Lake except for copepods. Food-web functional state did not change among food webs, but percentage of functional state contributing to total flux did vary. Herbivory was the dominant food-web functional state for all years, with the greatest percentage of flux from herbivory in 2011. In addition, by using a whole-ecosystem model that accounted for whirling disease and historical (natural) lake-level variation, I show that suppression of the lake trout population is necessary for cutthroat trout recovery, but the amount of suppression effort needed for cutthroat trout to reach recovery benchmarks is linked to severity of climate change. Additionally, if climate change increases the frequency and severity of reduced lake levels in the future, cutthroat trout recovery benchmarks may need to be adapted. With this research, I demonstrate how the feedbacks among predator-prey dynamics, disease, and climate change can complicate the suppression of invasive species and the conservation of invaded ecosystems and must be considered for establishing realistic conservation benchmarks.
Relating the reproductive performance of westslope cutthroat trout to trait specialization to screen for artificial selection vulnerability in a conservation hatchery
(Montana State University - Bozeman, College of Letters & Science, 2022) Preul-Stimetz, Taylor Nicole; Chairperson, Graduate Committee: Christine Verhille
To mitigate westslope cutthroat trout (WCT; Oncorhynchus clarkii lewisi) declines, Montana Fish, Wildlife, & Parks carries out large scale restorations, including wild-origin stocking efforts from conservation hatcheries. Although hatcheries have made progress in limiting the effects of artificial selection on stocked populations, concerns remain that rearing practices inadvertently reduce the diversity propagated into the wild. The objective of this research was to identify traits of WCT driving poor survival or reproduction in a hatchery, allowing managers to reduce artificial selection by screening for fish requiring alternative rearing. In Chapter 1, I repeatedly measured 18 behavior, morphology, and health traits from hatchery intake (July 2019) to spawn (June 2021). I identified traits with low within- relative to between-individual variation as traits likely to be indicative of specialization. As specialists tend to maximize performance under a narrow range of conditions, they may be vulnerable to artificial selection within hatcheries. In Chapter 2, I tested whether the specialized traits identified in Chapter 1, growth rate, or age at hatchery intake of individual WCT could predict survival or reproduction. In Chapter 1, I identified nine specialized (relative condition, weighted health index, health index, body shape, energetic reserves, latency, and upper jaw, lower jaw, and anal fin residual length) traits. I hypothesized these traits would predict later survival or reproductive performance. In Chapter 2, I identified October 2019 daily growth rate in weight and every replicate length measurement after October 2019 to strongly predict total ovulated eggs and total number of hatch embryos produced by females. However, among individual variation in the median percent hatch embryos was not explained by maternal size. Male gamete quality and fertilization success was consistently high, and I found no biologically significant predictors of reproductive performance for males. I also found no predictors of survival for males or females. Despite high total ovulated eggs and total hatch embryo success for females, variable female median percent hatch embryos suggests that quality of ovulated eggs is driving current limitations to WCT hatchery reproduction. I recommend further investigation into impacts of rearing stressors and post-ovulatory aging on female WCT and their reproductive performance.
Reproductive biology and phenology of western pearlshell mussels in Montana
(Montana State University - Bozeman, College of Letters & Science, 2022) Cook, Kristen Ann; Chairperson, Graduate Committee: Alexander V. Zale
The Western Pearlshell mussel is the only native freshwater mussel inhabiting trout streams of western Montana; it has been designated a state Species of Concern because of declines in abundance and distribution. Conservation of Western Pearlshells in Montana will require fundamental information on their reproduction and life-history traits that is currently lacking. We therefore estimated the age and length at sexual maturity and incidence of hermaphroditism in mussels using histology. We determined the timing of reproductive events (spawning, brooding, embryogenesis, larval release, and larval infestation of hosts) and their relationship to temperature by collecting gonadal and marsupial biopsies to identify gamete presence and embryo developmental stages, visually identifying brooding mussels, and examining captured fish for the presence of mussel larvae. We identified the hosts of Western Pearlshells in nature by quantifying the probability of infestation and infestation intensities among salmonid species. Mussels reached sexual maturity at an estimated 34 mm in length and 11.5 years of age. Of 31 mature mussels examined histologically, all but one were gonadal hermaphrodites. The reproductive phenology of Montana Western Pearlshells differed among populations and years. Mussel populations brooded for about 24 to 39 days in May and June. Embryogenesis was synchronous among individuals in all populations except one and was about two to three weeks in duration. The larval infestation period generally occurred in June and July and was 47 to 71 days in duration. Some larvae grew > 400% in length before leaving the host. Gonadal recrudescence was rapid whereby mussels possessed mature or nearly mature gametes by early autumn. Both photoperiod and temperature appear to influence the timing of reproductive events. Native Westslope Cutthroat Trout and nonnative Brook Trout were the most susceptible fish species to infestation of Western Pearlshell larvae. Nonnative Brown Trout were moderately susceptible to infestation in the Flint-Rock watershed. Nonnative Rainbow Trout and native Mountain Whitefish were least likely to be infested with mussel larvae. Our findings will inform future conservation and propagation efforts of Western Pearlshells in Montana.
African wild dog demography in an ecosystem with reduced prey and dominant competitors
(Montana State University - Bozeman, College of Letters & Science, 2021) Goodheart, Benjamin Michael; Chairperson, Graduate Committee: Scott Creel; Scott Creel, Matthew S. Becker, Milan Vinks, Kambwiri Banda, Carolyn Sanguinetti, Paul Schuette, Elias Rosenblatt, Chase Dart, Anna Kusler, Kim Young-Overton, Xia Stevens, Alstone Mwanza and Chuma Simukonda were co-authors of the article, 'Low apex carnivore density does not release a subordinate competitor when driven by prey depletion' in the journal 'Biological conservation' which is contained within this thesis.
Conservation of competitively subordinate carnivores presents a difficult challenge because they are limited by dominant competitors. Prey depletion is one of the leading causes of large carnivore decline worldwide, but little is known about the net effect of prey depletion on subordinate carnivores when their dominant competitors are also reduced. African wild dogs are often limited by high densities of dominant competitors, particularly lions. We measured African wild dog density and survival, using mark-recapture models fit to 8 years of data from 425 known individuals in the Greater Kafue Ecosystem, Zambia. The GKE is affected by prey depletion, particularly of large herbivores, and thus the density of lions is significantly lower than ecologically comparable ecosystems. Counter to expectations from mesopredator release theory, wild dog density in GKE was far lower than comparable ecosystems with higher lion and prey density, though annual survival rates were comparable to large and stable populations. Average pack size was small and home range size was among the largest recorded. Our results show that low lion density did not competitively release the GKE wild dog population and we infer that the low density of wild dogs was a product of low prey density. Our results suggest that there is an optimal ratio of prey and competitors at which wild dogs achieve their highest densities. This finding has immediate implications for the conservation of the endangered African wild dog, and broad implications for the conservation of subordinate species affected by resource depletion and intraguild competition.
Population structure, gene flow, and genetic diversity of Rocky Mountain bighorn sheep informed by genomic analysis
(Montana State University - Bozeman, College of Agriculture, 2020) Flesch, Elizabeth Pearl; Chairperson, Graduate Committee: Jennifer Thomson; Jay J. Rotella, Jennifer M. Thomson, Tabitha A. Graves and Robert A. Garrott were co-authors of the article, 'Evaluating sample size to estimate genetic management metrics in the genomics era' in the journal 'Molecular ecology resources ' which is contained within this dissertation.; Tabitha A. Graves, Jennifer M. Thomson, Kelly M. Proffitt, P.J. White, Thomas R. Stephenson and Robert A. Garrott were co-authors of the article, 'Evaluating wildlife translocations using genomics: a bighorn sheep case study' in the journal 'Ecology and evolution' which is contained within this dissertation.; Tabitha A. Graves, Jennifer M. Thomson, Kelly M. Proffitt and Robert A. Garrott were co-authors of the article, 'Genetic diversity of bighorn sheep population is associated with dispersal, augmentation, and bottlenecks' submitted to the journal 'Biological conservation' which is contained within this dissertation.
This dissertation evaluated the genomics of bighorn sheep (Ovis canadensis) herds across the Rocky Mountain West to determine optimal sample size for estimating kinship within and between populations (Chapter Two), to detect gene flow due to natural dispersal and translocations (Chapter Three), and to evaluate the correlation between genetic diversity and influences on population size (Chapter Four). To date, wildlife managers have moved many bighorn sheep across the Rocky Mountain West in an effort to provide new genetic diversity to isolated herds. However, little is known about the genetics of these herds and the real impacts of translocations. To learn how populations have been impacted by these management actions, we genotyped 511 bighorn sheep from multiple populations using a new cutting-edge genomic research technique, the Illumina Ovine High Density array, which contained about 24,000 to 30,000 single nucleotide polymorphisms informative for Rocky Mountain bighorn sheep. First, we determined that a sample size of 20 to 25 bighorn sheep was adequate for assessment of intra- and interpopulation kinship. In addition, we concluded that a universal sample size rule for all wild populations or genetic marker types may not be able to sufficiently address the complexities that impact genomic kinship estimates. Secondly, we synthesized genomic evidence across multiple analyses to evaluate 24 different translocation events; we detected eight successful reintroductions and five successful augmentations. One native population founded most of the examined reintroduced herds, suggesting that environmental conditions did not need to match for populations to persist following reintroduction. Finally, we determined that influences on population size over time were correlated with genetic diversity. Gene flow variables, including unassisted connectivity and animals contributed in augmentations, were more important predictors than historic minimum population size and origin (i.e. native vs. reintroduced). This hypothesis-based research approach will give wildlife managers additional biological insight to help inform various management options for bighorn sheep restoration and conservation.
Out-migration dynamics of juvenile adfluvial bull trout in tributaries to the lower Clark Fork River, Montana
(Montana State University - Bozeman, College of Letters & Science, 2021) Lewis, Madeline Collier; Chairperson, Graduate Committee: Christopher S. Guy; Christopher S. Guy, Eric W. Oldenburg and Thomas E. McMahon were co-authors of the article, 'Demographic characteristics and distribution of juvenile adfluvial bull trout at the tributary scale' submitted to the journal 'Transactions of the American Fisheries Society' which is contained within this thesis.; Christopher S. Guy, Eric W. Oldenburg and Thomas E. McMahon were co-authors of the article, 'Seasonal capture efficiencies influences knowledge of underlying out-migration dynamics in bull trout populations with juvenile downstream trap-and-haul programs' submitted to the journal 'North American journal of fisheries management' which is contained within this thesis.; Christopher S. Guy, Eric W. Oldenburg and Thomas E. McMahon were co-authors of the article, 'Individual characteristics and abiotic factors influence outmigration dynamics of juvenile bull trout' submitted to the journal 'Canadian journal of fisheries and aquatic sciences' which is contained within this thesis.
In the lower Clark Fork River, Montana, a two-way trap-and-haul program is implemented to conserve the adfluvial life-history strategy in Bull Trout Salvelinus confluentus populations in the presence of hydropower dams. We used the infrastructure in place for the program, including a permanent weir trap and multiple stationary PIT antennas, to evaluate the demographic characteristics and out-migration dynamics of juvenile bull trout, and assess the efficacy of the downstream trapping component of the trap-and-haul program. We PIT-tagged 821 juvenile Bull Trout in Graves Creek, and 144 Bull Trout in East Fork Bull River in the summer of 2019 and summer of 2020. Bull Trout in Graves Creek were primarily age 1 and age 2, with a small number of age-3 Bull Trout present (< 1%). In East Fork Bull River, age-3 Bull Trout represented 14% - 46% of the population, with a small number of age-4 and older Bull Trout present (4% - 6%). From July 2019 through December 2020, 308 tagged Bull Trout outmigrated from Graves Creek, and most out-migrants were age 2 (n = 221). In East Fork Bull River, 18 Bull Trout out-migrated, and most out-migrants were age 3 (n = 13). Capture efficiency of the permanent weir in Graves Creek varied from 83% to 100% in autumn 2019 and 2020 and was substantially lower in the spring (14%). The majority of Bull Trout out-migrated from Graves Creek during autumn 2019, spring 2020, or autumn 2020 trapping seasons (n = 276). In Graves Creek, the largest Bull Trout within the 2018 year-class were five times more likely to out-migrate at age 1 when compared to smaller fish within the cohort. The magnitude of age-1 out-migration was positively related to density. Relative changes in abiotic factors, including discharge, water temperature, and photoperiod, were cues to out-migration, and the direction of change varied by season. Understanding the demographic characteristics and outmigration dynamics of the Bull Trout in Graves Creek and East Fork Bull River enables more informed management of the trap-and-haul program and can be used to inform conservation efforts of other migratory Bull Trout populations.
Retrospective analysis of a declining trumpeter swan (Cygnus buccinator) population in Yellowstone National Park
(Montana State University - Bozeman, College of Letters & Science, 2021) Shields, Evan Michael; Chairperson, Graduate Committee: Jay J. Rotella
By 1933, the number of trumpeter swans (Cygnus buccinator) in the continental United States was reduced to roughly 70 individuals that nested and wintered in Yellowstone National Park (YNP) and the surrounding Greater Yellowstone area. While conservation measures saved the trumpeter swan, and their numbers have increased greatly across North America, abundance and productivity of YNP's resident trumpeter swan population declined from the 1960's through about 2010. Many hypotheses for the initial decline in YNP trumpeter swans exist, including human disturbance at nesting areas, changes in habitat quality, predation, and management of trumpeter swans outside of YNP. To improve knowledge and take advantage of long-term monitoring of trumpeter swans, this retrospective study was designed to evaluate the various competing hypotheses about possible factors associated with temporal and spatial variation in swan abundance and reproductive success in YNP for 1931-2019. Two different types of analyses were used: (1) analysis of annual park-wide counts of trumpeter swan territories with swans Absent, Present but unsuccessful (Present), and Successful, and (2) Bayesian reversible jump Markov chain Monte Carlo analysis that evaluated the utility of covariates representing swan decline hypotheses for explaining variation in annual, territory-level patterns of where swans were Absent, Present, and Successful each year. My results provide novel information on temporal patterns in the annual number of Absent, Present, and Successful territories, and analysis of covariates that are useful to explain variation in territory statuses identified several interesting covariate relationships. Swan territories within YNP were more likely to have trumpeter swans Present as opposed to Absent during 1931-2011 in years when total abundance of trumpeter swans in the broader geographic area around YNP was greater. Because several covariates have values that trend through time, it is difficult to distinguish between several alternative interpretations for the underlying causes of temporal trends. Identification of swan territories most likely to have swans Present and Successful can be a useful tool to help YNP staff manage important swan habitat or justify targeted management actions. Future work that utilizes satellite imagery to reconstruct lake/wetland hydrology is likely to be useful to describe potential changes in habitat quality.
Success of westslope cutthroat trout and arctic grayling conservation translocations in Yellowstone National Park, Montana and Wyoming, USA
(Montana State University - Bozeman, College of Letters & Science, 2021) Puchany, Andriana Rachel; Chairperson, Graduate Committee: Alexander V. Zale
Restoration of native Westslope Cutthroat Trout Oncorhynchus clarkii lewisi and fluvial Arctic Grayling Thymallus arcticus in Yellowstone National Park is a high priority for fishery managers. Restoration of the East Fork Specimen Creek and Grayling Creek watersheds included construction of fish barriers to isolate watersheds, application of rotenone to eliminate nonnative and hybridized fish, and translocations of native fish. We sampled these watersheds in 2018 and 2019 to evaluate the success of restoration efforts by 1) estimating the stage of recovery achieved by translocated populations, 2) determining contributions of Westslope Cutthroat Trout donor sources to the translocated populations in the East Fork Specimen Creek watershed by investigating their genetic ancestries, and 3) making comparisons of recovery between the East Fork Specimen and Grayling Creek watersheds. Recovery of Westslope Cutthroat Trout in both watersheds is progressing, with expected differences in stage of recovery between the two watersheds attributable to a 5-year difference in restoration timelines. Conversely, recovery of Arctic Grayling in Grayling Creek appears improbable without management intervention, but the surprising documentation of naturally reproduced individuals engenders a hopeful future for continued Arctic Grayling recovery efforts. Interspecific hybrid introgression discovered in Westslope Cutthroat Trout populations in East Fork Specimen and Grayling creeks probably resulted from barrier failure or incomplete eradication of hybrid fish during rotenone treatments. Whereas all Westslope Cutthroat Trout donor sources contributed to the recovering population in East Fork Specimen Creek, contributions were disproportionate to numbers translocated, indicating potential fitness differences among donor sources. Findings from this study have already helped Yellowstone National Park fishery managers make adaptive management decisions and will help inform future native fish conservation translocations.
Understanding mechanisms of invasion and restoring lands impacted by non-native annual grasses
(Montana State University - Bozeman, College of Agriculture, 2020) Majeski, Michelle Lynn; Chairperson, Graduate Committee: Jane M. Mangold; Catherine Zabinski, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Ventenata dubia growth responds to field soil inocolum but not phosphorous and potassium treatments' which is contained within this thesis.; Catherine Zabinski, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Ventenata dubia was associated with perennial grasses, bare ground and soil potassium concentration' which is contained within this thesis.; Stacy C. Simanonok, Zach Miller, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Spring seeding provides a seasonal priority effect for Pseudoroegneria spicata in Bromus tectorum-invaded rangelands' which is contained within this thesis.
European settlement and development of rangelands in the western U.S. has led to a shift in vegetation from native species to introduced species, some of which have become weedy and invasive. Effects of invasive plant species can vary but often include replacing native vegetation, altering ecosystems, affecting wildlife that relied on the native plants for food and shelter, and toxicity to livestock. Two introduced annual grasses of concern are Ventenata dubia and Bromus tectorum. These grasses are at different stages in their invasion in the western U.S. Ventenata dubia is a recent invasive species in the past ten years and B. tectorum has been dominant in the Intermountain West since the mid-1900s. Three independent studies were conducted to understand characteristics of V. dubia invasion and to test whether a seasonal priority effect could be shifted to Pseudoroegneria spicata to outcompete B. tectorum in range/pasturelands. A full-factorial design was executed in a greenhouse setting to examine if a plant-soil feedback contributes to V. dubia invasion and if V. dubia preferred specific nutrients for growth. Ventenata dubia biomass, shoot height and number of leaves and tillers (per plant) were higher when grown with field soil inoculum compared to sterilized greenhouse soil. Ventenata dubia growth varied among nutrient treatments, but trended higher with a full nutrient solution. A nested observational study was conducted to examine abiotic and biotic characteristics associated with V. dubia infestations. Ventenata dubia was positively associated with non-native perennial grasses and negatively associated with native perennial grasses, bare ground/rock and soil potassium concentration. A randomized split-plot design was performed in B. tectorum-infested range and pasturelands to test whether timing of herbicide application and seeding of P. spicata could create a seasonal priority effect for P. spicata. Bromus tectorum had lower cover and biomass (per m2) with spring herbicide application. Higher P. spicata density, cover and biomass resulted with spring seeding after B. tectorum was reduced. These studies show that established and seeded native perennial grasses can compete with nonnative, invasive annual grasses. When existing management tools (herbicide and revegetation) are applied in a different way, native perennial grasses benefit.

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