Theses and Dissertations at Montana State University (MSU)
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Item 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.Item Combination of acoustic telemetry and side-scan sonar provides insight for lake trout Salvelinus namaycush suppression in a submontane lake(Montana State University - Bozeman, College of Letters & Science, 2021) Siemiantkowski, Michael James; Chairperson, Graduate Committee: Christopher S. GuyExpansion of an invasive Lake Trout Salvelinus namaycush population in Swan Lake, Montana threatens a core area population of Bull Trout Salvelinus confluentus in Montana. Given the increased efficacy of suppression using novel embryo suppression methods, there is renewed interest in Lake Trout suppression in Swan Lake. The specific questions of this study were: 1) where are Lake Trout spawning, 2) where are the most used spawning sites, 3) what is the amount of spawning habitat, 4) does the estimated spawning area differ between estimates from telemetry locations and side-scan sonar imagery of suitable spawning substrate, and 5) how much phosphorous and nitrogen would be added to Swan Lake if carcass-analog pellet treatments were implemented? Acoustic tags were implanted in 85 Lake Trout in July and August of 2018 and 2019. Nightly tracking efforts during September, October, and November of 2018 and 2019 resulted in 1,744 relocations for 49 individual Lake Trout. Kernel-density analysis was used to evaluate Lake Trout aggregation locations identifying 10 distinct spawning sites -- corroborating previous studies. Visual observation of Lake Trout embryos confirmed spawning at three sites with the remaining seven sites considered to be unconfirmed spawning sites. All confirmed spawning sites were located in the littoral zone along areas of steep bathymetric relief and were the most used across both spawning seasons. In 2019, side-scan sonar imaging was used to classify and quantify the total area of suitable spawning substrate, which comprised 12.8% of the total surface area estimated for confirmed sites and 11.4% for unconfirmed spawning sites. Simultaneous treatment of all confirmed and unconfirmed spawning sites would require 205,709 + or - 86 kg of carcass-analog pellet material, resulting in 370.4 + or - 0.2 kg of phosphorous and 7,487.9 + or - 3.1 kg of nitrogen inputs to Swan Lake. Thus, pellet treatment would increase the Carlson's trophic state index (TSI) values from 20.8 to 27.7 for total phosphorous, and from 22.1 to 26.2 for total nitrogen. Based on a TSI threshold value of < 40 for an oligotrophic lake, the use of carcass-analog pellets could be a feasible addition to renewed Lake Trout suppression efforts in Swan Lake.Item Subadult bull trout out-migration in the Thompson River drainage, Montana(Montana State University - Bozeman, College of Letters & Science, 2017) Glaid, Jeffrey Robert; Chairperson, Graduate Committee: Christopher S. GuyBull Trout populations in the Thompson River drainage have declined over the past century. Declines have been attributed to habitat fragmentation, habitat degradation, and non-native species. Out-migration characteristics (e.g., temporal and spatial origins, abiotic cues, and movement) of subadult Bull Trout (100 - 300 mm TL) were evaluated throughout the drainage to increase our understanding of local populations and better inform conservation efforts. In autumn 2014, 53 subadult Bull Trout were tagged with passive integrated transponder (PIT) tags; 29 were also surgically implanted with acoustic transmitters. Minimal Bull Trout out-migration (N = 7) was observed in 2014. In summer 2015, 566 subadult Bull Trout were PIT-tagged in the Fishtrap Creek and West Fork Thompson River drainages (Thompson River tributaries). Stream-width PIT antennas were used to monitor out-migration at the confluences of the Thompson River tributaries and at the mouth of the Thompson River. Out-migrating Bull Trout (N = 135) were sampled using directional weir traps at the tributary confluences, PIT-tagged, and implanted with acoustic- (N = 29) or radio-tags (N = 14) in autumn 2015. From July through December 2015, 10.1% of all PIT-tagged Bull Trout out-migrated from the Thompson River tributaries (11.4% of fish in the Fishtrap Creek drainage [N = 420] and 6.2% of fish in West Fork Thompson River [N = 146]), with peak out-migration occurring in late October. Highest predicted probabilities of Bull Trout out-migration occurred at lengths of 179 mm in Fishtrap Creek (30.4%) and 165 mm in West Fork Thompson River (29.3%). Only 13.5% of all Bull Trout that entered the Thompson River (N = 192) entered Thompson Falls Reservoir, with peak out-migration occurring in December. Median daily water temperature, minimum daily atmospheric pressure, and lunar illumination were weakly associated with an increase in the number of out-migrants. Radio-tagged out-migrants were randomly distributed throughout the Thompson River and exhibited long periods of site fidelity between intermittent downstream movements. Bull Trout demonstrated low out-migration rates in the Thompson River drainage and prolonged habitation of the mainstem Thompson River, which was contrary to the a priori hypothesis of clustered out-migration by subadult Bull Trout.Item Efficacy of suppressing non-native lake trout in an isolated backcountry lake in Glacier National Park(Montana State University - Bozeman, College of Letters & Science, 2014) Fredenberg, Carter Roger; Chairperson, Graduate Committee: Christopher S. GuyPrior to the recent invasion of non-native lake trout Salvelinus namaycush, Glacier National Park (GNP) supported approximately one-third of the remaining natural lake habitat supporting threatened bull trout Salvelinus confluentus. However, bull trout populations have recently declined and are at high risk of extirpation in several lakes in western GNP due to the establishment of lake trout. In 2009, the U.S. Geological Survey and the National Park Service began suppressing lake trout in Quartz Lake (352 ha) to reduce impacts to native bull trout. The objectives of this study were to: (1) describe the demography of the lake trout population during the suppression program (2009-2013); (2) identify the timing and location of lake trout spawning; (3) determine the most efficient combination of gill net mesh color and twine diameter to capture juvenile lake trout (age 2 to age 4); (4) assess the effects of suppression on the growth rate of the lake trout population and use this information to model harvest scenarios; and (5) determine whether suppression negatively impacted bull trout. Lake trout exhibited slower growth, lower condition, and lower fecundity relative to other populations. Spawning locations were identified on cobble and boulder substrates (depths 2-20 m) near the base of two avalanche chutes where adults began aggregating between 1 and 9 October prior to thermal destratification (11-12 C°). Catch rates of spawning (ripe) adults were highest 12-25 October when temperatures declined to below 10 C°. Gill nets with 0.1 mm twine thickness and green color increased catchability of juvenile lake trout. Although density dependent parameters were not included, population simulation models indicated the population was growing exponentially and would likely reach carrying capacity within ten years without suppression. Suppression resulted in declining population growth rates (lambda) from 1.23 prior to suppression to 0.61-0.79 during suppression. Bull trout redd abundances remained stable throughout the suppression period. My results indicate targeted suppression successfully reduced lake trout abundance and that continued suppression at or above observed exploitation levels is needed to ensure continued population declines and to avoid impacts to the bull trout population.Item Feasibility assessment for translocation of imperiled bull trout populations in Glacier National Park, Montana(Montana State University - Bozeman, College of Letters & Science, 2014) Galloway, Benjamin Thomas; Co-chairpersons, Graduate Committee: Christopher S. Guy and Clint MuhlfeldTranslocations are becoming an important tool for conservation and recovery of native fishes. However, many translocations have been unsuccessful likely due to inadequate feasibility assessments of abiotic and biotic factors influencing translocation success prior to implementation. This study provides a framework developed to assess the feasibility of translocating threatened bull trout Salvelinus confluentus into novel stream and lake systems in Glacier National Park, Montana (GNP). Populations of bull trout in GNP are at risk of extirpation in several lakes due to the establishment of nonnative invasive lake trout S. namaycush. Drainage-specific translocations of extant bull trout populations have been proposed as a possible management solution to these declines, but the suitability of translocation sites is unknown. This study evaluated the suitability of spawning, rearing, foraging, and overwintering habitats in three isolated headwater stream and lake systems (Logging, Camas, and Lincoln sites) to determine their suitability for bull trout translocation. A scoring framework was developed to compare the suitability of proposed translocation sites based on three major components: potential for the recipient habitat to support a translocation; potential for the translocation to negatively impact native aquatic biota; and ability of within-drainage donor populations to support a translocation. Scoring criteria were developed based on abiotic and biotic characteristics known to influence translocation success, including water temperature, habitat quantity and quality, habitat complexity, species composition, and the possibility of conducting within-drainage translocation. Based on the framework, the Camas site is the most suitable for translocation because it contains physical and biological conditions comparable to other systems supporting bull trout. The Logging site is the second most suitable site for translocation, whereas the Lincoln site is least suitable because it contains a minimal amount of stream habitat (< 300 m) and nonnative brook trout. These results will be used to prioritize and plan potential translocation strategies for imperiled bull trout populations in GNP and provide a framework for evaluating the feasibility of conducting translocations elsewhere.Item Ecology of lacustrine-adfluvial bull trout populations in an interconnected system of natural lakes(Montana State University - Bozeman, College of Letters & Science, 2008) Meeuwig, Michael Hendrik; Chairperson, Graduate Committee: Christopher S. GuyLoss of connectivity among populations and interactions with nonnative species can negatively influence abundance of bull trout Salvelinus confluentus. Connectivity among bull trout populations and trophic relationships among native and nonnative fishes in Glacier National Park (GNP), Montana, were examined. Competition between juvenile (< or equal to 80 mm) bull trout and lake trout S. namaycush for cover habitat was examined in a laboratory environment. Connectivity among bull trout populations was inferred from genetic data. Barriers (i.e., waterfalls > or equal to 1.8 m) reduced genetic diversity and increased genetic differentiation among populations. Genetic differentiation was positively related to the length of tributary stream sections between populations and populations within the same drainage were more similar than populations in different drainages. Competition between bull trout and nonnative lake trout for prey is a potential mechanism for declines in bull trout abundance. Stable isotopes analyses were used to examine trophic relationships among fishes in GNP lakes. Bull trout and lake trout were top-level predators among lakes (Delta15N analysis), lake trout occupied a higher trophic position than bull trout (Delta15N analysis), and bull trout and lake trout likely used different foraging habitats (Delta13C analysis). These data do not support the prediction that these species are complete competitors for prey resources in GNP. Cover habitat protects fish from predators and is competed for if limiting. Habitat use by juvenile bull trout and lake trout was experimentally evaluated. Bull trout and lake trout differed in habitat use. Lake trout avoided bottom habitat, bull trout avoided water column habitat when lake trout were present, and neither species selected cover habitat. The hypothesis that bull trout and lake trout compete for cover habitat was not supported. The landscape in GNP allows connectivity among bull trout populations that are not isolated by barriers and one-way dispersal past waterfalls is likely. This connectivity allows dispersal and colonization by nonnative fishes into GNP lakes. Bull trout and nonnative lake trout are not complete competitors for prey resources in GNP or cover habitat; however, future studies should examine trophic shifts by these species associated with prey limitation and diel variability in habitat use by these species.Item Spawning and early life-history characteristics of bull trout in a headwater-lake ecosystem(Montana State University - Bozeman, College of Letters & Science, 2010) Tennant, Lora Beth; Chairperson, Graduate Committee: Christopher S. Guy; Robert E. Gresswell (co-chair)Bull trout, Salvelinus confluentus, are in decline throughout their native range. Interaction with nonnative species is considered to be one of the drivers of bull trout decline. Bull trout exhibit a variety of life-history strategies and lacustrine-adfluvial bull trout seem to be particularly susceptible to population decline when nonnative lake trout, S. namaycush, invade or are introduced into lakes where bull trout are the dominant salmonid. Quartz Lake in Glacier National Park, Montana, provided a unique opportunity to gather information on the spawning and early life-history characteristics of a bull trout population prior to anticipated declines in bull trout abundance due to lake trout invasion. The objectives of this study were (1) to characterize the spatial and temporal dynamics of bull trout spawning migrations and associate areas of high redd accumulation to abiotic factors, and (2) to quantify the influence of abiotic factors on the distribution of subadult bull trout in tributary streams of Quartz Lake. Stream surveys were conducted to quantify physical habitat characteristics in the study area, backpack electrofishing was used to sample subadult bull trout rearing in lake tributaries, and redd surveys were used to investigate the spatial and temporal trends in the accumulation of bull trout redds. Bull trout redds and subadult bull trout were found throughout the study area; however, bull trout spawning and rearing appeared to be concentrated in lower Quartz Creek. This area was low gradient, and there was a high percent of gravel and cobble substrates. Bull trout spawning began in late September, peaked in early October, and concluded in mid-October. These data provide important information on bull trout life-history in headwater lakes and provide biologists with baseline data that will be useful for assessing the effects of lake trout suppression efforts that began in 2009.