Thesis (Ph. D.)--Montana State University--Bozeman, 2006. / Typescript. Chairperson, Graduate Committee: Mark L. Taper. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 148-161). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Resident bull trout (Salvelinus confluentus) may be particularly vulnerable to human related disturbance, however very few studies have focused on resident bull trout populations. The abundance of bull trout is one measure of the strength and potential for persistence of a population. Habitat characteristics may influence resident bull trout abundance to differing degrees and by varying means at multiple spatial scales. We used day and night snorkel counts to assess relative bull trout abundance. A modification of the Forest Service R1/R4 Fish and Fish Habitat Inventory was used to assess habitat characteristics associated with resident bull trout. Logistic and multiple linear regression were used to assess the relationships between resident bull trout abundance and habitat characteristics at the patch (1 to 5 km), reach (0.5 to 1 km) and habitat unit (1 to 100 m) scales. Site categorical variables were used along with quantitative habitat variables to explain among-site and across-site variation in the data. The significance of both quantitative habitat variables and categorical site variables at various spatial scales suggest that relationships between bull trout abundance and habitat characteristics are complex and in part dependent on scale. The characteristics of individual habitat units explained little of the variation in bull trout presence/absence (logistic regression; Somers' D=0.44) and density (multiple linear regression; adjusted R��=0.08) in habitat units, however there were habitat characteristics that were significantly (P���0.05) correlated to bull trout presence/absence and density in habitat units. The relationships between habitat characteristics and bull trout presence/absence and density varied between habitat unit types. There was a strong quadratic relationship between bull trout abundance and mean summer water temperature at the reach (P=0.004) and patch scales (P=0.001). The mean temperature of patches appears to explain some of the variation in bull trout density at smaller spatial scales, such as reaches and habitat units. An appreciation of the complex nature of scale dependent interactions between bull trout abundance and habitat characteristics may help resource managers make wiser decisions regarding conservation of resident bull trout populations. / Graduation date: 2000

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 135-150).

Bull trout are a species of fish native to the coldwater mountain streams of Alberta. Because this species is of special conservation concern and displays finely dissected population structure, it is well suited as a model species to test the utility of versatile conservation genetics tools. One such tool, a genetic clustering method, was used to discern the hierarchical population structure of bull trout in the core of their range in South-West Alberta. The method also revealed patterns of gene flow by way of assignment tests. Populations defined by this method were then used as reference populations for mixed-migrant assignment tests, revealing that clustering method-defined populations may be more suitable for such tests rather than traditional approaches that define reference populations by sampling location. Combined with spatial data a posteriori, assignment tests had additional utility of discerning spatial scale of movement for juvenile and adult salmonids. This technique provided further evidence that assignment tests may be powerful indirect tools for evaluating migration, and that longrange inter-stream dispersal in juvenile salmonid fish may be more common than previously assumed. / xi, 174 leaves : ill. ; 29 cm. --

Distribution and life history characteristics of lacustrine-adfluvial bull trout (Salvelinus confluentus) were described in the North Fork Skokomish River Basin (including Lake Cushman, a reservoir) from 1994 to 1996. Day snorkeling was conducted in the river to determine initiation of the bull trout spawning migration, abundance of spawners, and duration of spawning. Declining photoperiod, increased river discharge, and decreased water temperature appeared to influence timing of migration and spawning. Lacustrine-adfluvial bull trout typically entered the North Fork Skokomish River in October although some fish entered as early as May. Mean lengths of spawners consistently increased from June to December 1996, and early migrating bull trout were shorter than those fish that entered after river discharge increased in October. The presence of two phases of the spawning migration may be indicative of two populations spawning in the river. Bull trout spawned between mid-September and December in the river and tributaries after water temperatures declined. All spawning occurred at temperatures less than 7.5��C. Comparisons with studies of other lacustrine-adfiuvial bull trout populations that inhabit river and reservoir complexes suggested that bull trout exhibit specific migratory strategies related to local environmental conditions. In the North Fork Skokomish River, changes in abundance of bull trout, mountain whitefish (Prosopium wilhamsom), cutthroat trout (Oncorhynchus dark), and rainbow trout (Oncorhynchus mykiss) revealed distinct temporal segregation among these species. Olympic National Park, a designated Biosphere Reserve, contains one of the largest remaining areas of relatively pristine habitat in the range of bull trout. Knowledge of responses of bull trout to changes in river discharge and temperature from relatively undisturbed systems, such as the North Fork Skokomish River, may be useful in understanding patterns observed in degraded environments. / Graduation date: 1998

Effective conservation strategies for imperiled species require an understanding of processes that influence fitness throughout the organism's life cycle and across the range of habitats needed to complete that cycle. I evaluated factors that affect population viability of bull trout Salvelinus confluentus, a threatened freshwater char species, throughout individual life stages and over the entire life cycle. I assessed the relationship between bull trout egg incubation success and environmental variables. Egg survival was negatively related to the percent of fine sediment in redds and positively related to hydraulic conductivity and the strength of downwelling. Next, I quantified juvenile bull trout survival rates and described movement patterns for this life stage. Juvenile bull trout emigrated from natal headwaters into larger rivers throughout the entire year and across a range of sizes. Estimates of juvenile survival rates improved dramatically when emigration was incorporated into the analysis. I integrated my observations of bull trout survival, growth, and movement to create a life-cycle model, which I used to better understand how populations respond to changes in specific demographic rates. Bull trout populations were particularly sensitive to changes in juvenile growth and survival. The relative effect of changes to fertility rates and adult survival varied depending upon whether a population was composed primarily of large, migratory, or smaller, resident individuals. Dispersal helped to lower the probability of extinction for small or declining populations when neighboring populations were stable. My research demonstrates that bull trout require access to habitats throughout entire watersheds to maintain population viability. My results suggest that limiting anthropogenic sources of fine sediment and maintaining areas of channel complexity that promote downwelling can be important for bull trout embryo survival. Management decisions should also consider the diverse behavior of juvenile bull trout and the wide range of habitat they use. Additionally, connectivity between populations is likely to be important for declining populations to persist. The diversity of life-history strategies expressed by bull trout helps maintain demographic stability within and among populations. As such, preservation of habitat integrity and full life-history diversity is imperative for conservation and recovery of bull trout populations range-wide.

Effective conservation strategies for imperiled species require an understanding of processes that influence fitness throughout the organism's life cycle and across the range of habitats needed to complete that cycle. I evaluated factors that affect population viability of bull trout Salvelinus confluentus, a threatened freshwater char species, throughout individual life stages and over the entire life cycle. I assessed the relationship between bull trout egg incubation success and environmental variables. Egg survival was negatively related to the percent of fine sediment in redds and positively related to hydraulic conductivity and the strength of downwelling. Next, I quantified juvenile bull trout survival rates and described movement patterns for this life stage. Juvenile bull trout emigrated from natal headwaters into larger rivers throughout the entire year and across a range of sizes. Estimates of juvenile survival rates improved dramatically when emigration was incorporated into the analysis. I integrated my observations of bull trout survival, growth, and movement to create a life-cycle model, which I used to better understand how populations respond to changes in specific demographic rates. Bull trout populations were particularly sensitive to changes in juvenile growth and survival. The relative effect of changes to fertility rates and adult survival varied depending upon whether a population was composed primarily of large, migratory, or smaller, resident individuals. Dispersal helped to lower the probability of extinction for small or declining populations when neighboring populations were stable. My research demonstrates that bull trout require access to habitats throughout entire watersheds to maintain population viability. My results suggest that limiting anthropogenic sources of fine sediment and maintaining areas of channel complexity that promote downwelling can be important for bull trout embryo survival. Management decisions should also consider the diverse behavior of juvenile bull trout and the wide range of habitat they use. Additionally, connectivity between populations is likely to be important for declining populations to persist. The diversity of life-history strategies expressed by bull trout helps maintain demographic stability within and among populations. As such, preservation of habitat integrity and full life-history diversity is imperative for conservation and recovery of bull trout populations range-wide.

Bull trout (Salvelinus confluentus) populations from Alberta river drainage systems were compared using molecular techniques. Restriction fragment length polymorphisms (RFLP's) within the NDI and ND5/6 regions of the mitochondrial genome were observed. In addition, randomly amplified polymorphic DNA profiles (RAPD's) from total genomic DNA extracts were compared. Interdrainage comparisons using mtDNA revealed significant population heterogeneity among Alberta bull trout. Percent sequence divergence in mtDNA ranged from 0.14% to 0.92%. Most fish in each population were composed of a small number of common haplotypes, and the remaining fish displayed rare or locally unique haplotypes. RAPD profiles were used to calculate genetic distance values for Alberta, Canada and Montana, U.S.A. populations. Both Nei and Cavalli-Sforza distance values were used to generate neighbor-joining, FITCH and KITSCH distance trees. Two genetically distinct groups of bull trout were revealed by the RAPD analysis and the possiblity that post-glacial bull trout populations are derived from two separate refugia is suggested. / xvii, 161 leaves : ill. ; 28 cm.