Download or read book Reconstructing the Population History of Native Westslope Cutthroat Trout Oncorhynchus Clarki Lewisi in Avalanche Lake Through Analysis of Fossil Zooplankton Assemblages in Profundal Sediments Glacier National Park Montana written by Dirk Verschuren and published by . This book was released on 1993 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cutthroat written by Pat Trotter and published by Univ of California Press. This book was released on 2008 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cutthroat tells the full story of the genuine native trout of the American West. This new edition, thoroughly revised and updated after 20 years, synthesizes what is currently known about one of our most interesting and colorful fishes, includes much new information on its biology and ecology, asks how it has fared in the last century, and looks toward its future. In a passionate and accessibly written narrative, Patrick Trotter, fly fisher, environmental advocate, and science consultant, details the evolution, natural history, and conservation of each of the cutthroat's races and incorporates more personal reflections on the ecology and environmental history of the West's river ecosystems. The bibliography now includes what may be the most comprehensive and complete set of references available anywhere on the cutthroat trout. Written for anglers, nature lovers, environmentalists, and students, and featuring vibrant original illustrations by Joseph Tomelleri, this is an essential reference for anyone who wants to learn more about this remarkable, beautiful, and fragile western native.
Download or read book Natural Variation in Spotting Hyoid Teeth Counts and Coloration of Yellowstone Cutthroat Trout written by Ross V. Bulkley and published by . This book was released on 1963 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Differences in hyoid teeth and spotting counts among samples from four related populations of Yellowstone cutthroat trout, Salmo clarki lewisi Girard, reached species and subspecies levels as defined by some workers. Body coloration varied significantly among fish in six spawning runs of Yellowstone Lake, Wyo. The use of coloration, spotting, and hyoid teeth counts in cutthroat trout for taxonomic purposes needs reevalution.
Download or read book Management and Life History Consequences of Hybridization Between Westslope Cutthroat Trout oncorhynchus Clarkii Lewisi and Rainbow Trout oncorhynchus Mykiss written by Matthew Corsi and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The role of introductions of nonnative fishes in the decline of native fishes cannot be overstated. Westslope cutthroat trout (Oncorhynchus clarkii lewisi, WCT) are a salmonid native to the northern Rocky Mountains. These trout hybridize with rainbow trout (O. mykiss, RBT) where they are sympatric; however, in portions of the WCT range where RBT have been introduced, hybridization appears to spread rapidly and threatens continued existence of WCT. The conservation value of these hybridized populations is equivocal, and a better knowledge of the ecological, demographic, behavioral, and genetic consequences of hybridization is needed to better inform conservation strategies. I investigated three related questions: specifically, what landscape factors are associated with estimates of introgression; what are life history differences between WCT and hybrids; and what are tradeoffs in restoring migratory life history in populations threatened by hybridization? The riverscape context plays a substantial role in the distribution of hybrids, as estimates of introgression declined with increases in stream slope, elevation, and distance from a primary source of RBT, three correlated landscape variables. Spatial variation in patterns of hybridization suggests clarifying objectives for sampling and careful designs are necessary to adequately understand the status of populations. Variation in location may relate to some of the ecological differences, such as growth, among fish with different levels of introgression. In the Jocko River, hybrids with ancestry> 20% RBT demonstrated higher growth, earlier migration, increased egg size, and lower fecundity versus WCT. These lines of evidence demonstrate the importance of limiting further hybridization even in populations that already have low levels of hybridization. Given that many unaltered populations currently reside in isolated habitat fragments, I evaluated several demographic tradeoffs of restoring a migratory life history weighed against the risks of increased potential for hybridization from removing barriers or selectively passing migratory fish above the barriers using both matrix and genetic population models. Restoration of migratory life history substantially increases population viability; however, hybridization in above-barrier population increases predictably relative to hybridization status of below-barrier population, which may reduce viability if vital rates are reduced in hybrids. Hybridization creates a challenging set of management problems, but this research adds several important pieces to the puzzles to help develop and evaluate conservation strategies.
Download or read book Factors Influencing the Distribution of Bull Trout and Westslope Cutthroat Trout West of the Continental Divide in Glacier National Park written by Vincent Stephen D'Angelo and published by . This book was released on 2010 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reported decline of native bull trout Salvelinus confluentus and westslope cutthroat trout Oncorhynchus clarkii lewisi populations west of the Continental Divide in Glacier National Park (GNP) prompted research to identify critical habitats and investigate factors influencing their distribution and relative abundance. I evaluated the association of six abiotic factors (stream width, elevation, gradient, large woody debris density, pool density, mean August stream temperature) and a biotic factor (the presence of nonnative lake trout, Salvelinus namaycush) with the occurrence and density of bull trout and westslope cutthroat trout in 79 stream reaches in five sub-drainages of the North Fork Flathead River in GNP. Logistic and linear regression models were used to quantify the influence of these independent variables on species occurrence (presence/absence) and density (age-1 or older fish/100m2), and an information theoretic approach (AICc) was used to determine the most plausible combinations of variables in each case. The occurrence of westslope cutthroat trout was negatively associated with the presence of lake trout and positively associated with large woody debris and water temperature. Westslope cutthroat were detected throughout a wide range of water temperatures (8.5-16oC), stream sizes and elevations, but were most abundant in small, complex streams that were not connected to lakes supporting lake trout. Bull trout occurrence was positively related to stream width and negatively related to channel gradient and water temperature. Bull trout were most abundant in narrow (
Download or read book Conservation Status of Colorado River Cutthroat Trout written by and published by . This book was released on 1996 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluctuations in Age Composition and Growth Rate of Cutthroat Trout in Yellowstone Lake written by Ross V. Bulkley and published by . This book was released on 1961 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Age composition, growth rate, and year-class strength of Yellowstone Lake cutthroat trout from collections made in 1948 and from 1950 to 1959 are analyzed to relate total catch changes in age composition and growth rate. An increase in growth rate of fish fully recruited to the fishery and a decrease in percentages of fish belonging to age groups VI and VII are attributed to an increase in fishing pressure. Mean age of the catch varied with year-length of the catch has remained high, suggesting that production is more efficient now than in past years. Maximum equilibrium yield may be near. If the catch continues to increase at the present rate, it may become excessive within the next few years.
Download or read book Mortality Studies on Cutthroat Trout in Yellowstone Lake by Orville P Ball and Oliver B Cope written by Orville P. Ball and published by . This book was released on 1961 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a study of the Yellowstone Lake cutthroat trout, Salmo clarki lewisi, by the U.S. Fish and Wildlife Service, effects of environment on mortality of eggs, immature fish, spawners, and postspawners were measured for various components of the population in Yellowstone Lake (Wyoming). Five methods for estimating mortality of adults on spawning runs are described, with counting and tagging as the principal procedures. Of the total number of eggs deposited in the gravel, 60 to 75 percent died before hatching, and 99.6 percent had died by the time the fingerlings enetered Yellowstone Lake. In Arnica Creek runs, 48.6 percent died in the stream, 40.2 died later in the lake of natural causes, 7.6 were taken by fishermen, and 3.6 percent were alive 2 years later. The white pelican is a serious predator on cutthroat trout in Yellowstone Lake. From 1949 to 1953 fishermen caught 11.6 percent of the catchable trout available to them. Migrations of adult fish in Yellowstone Lake were traced through tagging.
Download or read book The Ecological Consequences of Hybridization Between Native Westslope Cutthroat Trout Oncorhynchus Clarkii Lewisi and Introduced Rainbow Trout O Mykiss in South Western Alberta written by Michael D. Robinson and published by . This book was released on 2007 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Movement and Population Structure of Westslope Cutthroat Trout Oncorhynchus Clarki Lewisi Inhabiting Headwater Stream of Montana written by and published by . This book was released on 1999 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Adaptation of Westslope Cutthroat Trout Oncorhynchus Clarkii Lewisi written by Daniel Patrick Drinan and published by . This book was released on 2010 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book High Mountain Conservation in a Changing World written by Jordi Catalan and published by Springer. This book was released on 2017-08-03 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides case studies and general views of the main processes involved in the ecosystem shifts occurring in the high mountains and analyses the implications for nature conservation. Case studies from the Pyrenees are preponderant, with a comprehensive set of mountain ranges surrounded by highly populated lowland areas also being considered. The introductory and closing chapters will summarise the main challenges that nature conservation may face in mountain areas under the environmental shifting conditions. Further chapters put forward approaches from environmental geography, functional ecology, biogeography, and paleoenvironmental reconstructions. Organisms from microbes to large carnivores, and ecosystems from lakes to forest will be considered. This interdisciplinary book will appeal to researchers in mountain ecosystems, students and nature professionals. This book is open access under a CC BY license.
Download or read book Effects of Temperature on Survival and Growth of Westslope Cutthroat Trout and Rainbow Trout written by Elizabeth Ann Bear and published by . This book was released on 2005 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Westslope cutthroat trout Oncorhynchus clarkii lewisi have declined throughout their native range in the Northern Rockies and were considered for listing under the federal Endangered Species Act. Water temperature is widely regarded as playing a key role in determining their persistence, but specific lethal levels and thermal optima for this cutthroat trout subspecies had not been precisely defined. This laboratory study used the acclimated chronic exposure method to determine tolerances and thermal optima of westslope cutthroat trout and rainbow trout Oncorhynchus mykiss, a potential nonnative competitor now occupying much of the former range of westslope cutthroat trout. Rainbow trout had a distinct survival advantage over westslope cutthroat trout at warmer temperatures. The ultimate upper incipient lethal temperature (temperature at which 50% of the population survives for 60-d) of rainbow trout (24.3°C; 95% CI, 24.0-24.7°C) was 4.7°C higher than that of westslope cutthroat trout (19.6°C; 95% CI, 19.1-19.9°C). In contrast, the optimum growth temperature for westslope cutthroat trout (13.6°C; 95% CI, 10.3-17.0°C) over the 60-d test period was very similar to that of rainbow trout (13.1°C; 95% CI, 6.8-18.2°C), although rainbow trout grew better over a wider range and at higher temperatures than did westslope cutthroat trout. The upper lethal and optimum growth temperatures for westslope cutthroat trout are in the lower range among most salmonids. The higher upper temperature tolerance of rainbow trout and its greater ability for growth at warmer temperatures may account for its increased occurrence at lower elevations than cutthroat trout. Water quality standards setting maximum daily temperatures from 13-15°C, near the optimum growth temperature, would ensure suitable thermal habitat to maintain the persistence of westslope cutthroat trout populations. In addition, survival and growth parameters indicated in this study can be used with stream temperature modeling to predict suitable habitat for westslope cutthroat trout, as they may be particularly susceptible to increases in stream temperature associated with climate change. Such predictions of habitat suitability will be vital in prioritizing conservation efforts with respect to reintroduction and translocation of westslope cutthroat trout.
Download or read book Genetic Considerations for the Conservation and Management of Yellowstone Cutthroat Trout Oncorhynchus Clarkii Bouvieri in Yellowstone National Park written by David Joel Janetski and published by . This book was released on 2006 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: A key component to conservation is an accurate understanding of genetic subdivision within a species. Despite their ecological and economic importance, relatively little is understood about the genetic structuring of Yellowstone cutthroat trout in Yellowstone National Park. Here, we use traditional (Fst, Rst, Nm, and AMOVA) and modern (Bayesian assignment tests, coalescent theory, and nested clade analysis) analytical approaches to describe the population genetic subdivision of cutthroat trout spawning populations in Yellowstone Lake and to identify genetically distinct population segments throughout Yellowstone National Park. Evidence for restricted gene flow between spawning populations within Yellowstone Lake was detected using nested clade analysis. This is the first molecular evidence for restricted gene flow between spawning populations in Yellowstone Lake. In contrast, traditional methods such as Fst and Rst as well as the Bayesian clustering program STRUCTURE v2.0 failed to detect evidence for restricted gene flow. Across our sampling range within Yellowstone National Park, eleven genetically distinct cutthroat trout population segments were detected. These showed a general pattern of small, isolated populations with low genetic diversity in headwater streams and wide-spread, genetically diverse populations in higher-order rivers. We recommend populations be managed to maintain current levels of genetic diversity and gene flow. Based on the recent decline of and distinct morphological, behavioral, and genetic nature of cutthroat trout in Yellowstone Lake, we recommend the Yellowstone Lake spawning populations collectively be recognized as an evolutionarily significant unit.
Download or read book Effects of Introduced Lake Trout on Native Cutthroat Trout in Yellowstone Lake written by James R. Ruzycki and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The establishment of a reproducing population of nonnative lake trout (Salvelinus namaycush) poses a serious threat to the integrity of the Yellowstone Lake ecosystem, particularly to the indigenous cutthroat trout (Oncorhynchus clarki bouvieri). We used standard fisheries techniques to quantify the population-level impact resulting from this introduction, while the U.S. National Park Service (NPS) developed a program to control their numbers. Lake trout diets, thermal history, growth, and size structure were incorporated into a bioenergetics model to estimate the predatory impact of introduced lake trout and to evaluate the effectiveness of the NPS lake trout control program. Population size structures were estimated from catches of fish in gill nets that were corrected for mesh size selectivity. Lake trout abundance was estimated using virtual population (cohort) analysis, and cutthroat trout abundance was estimated using hydroacoustics. Juvenile cutthroat trout were highly vulnerable to predation, and lake trout preyed on cutthroat trout that averaged 27?33% of their body length. Based on our model, an average piscivorous lake trout consumed 41 cutthroat trout each year. During 1996, the piscivorous lake trout population consumed an estimated 15 metric tons of cutthroat trout (129 000 fish) composing 14% of the vulnerable cutthroat trout production. The NPS removed nearly 15 000 lake trout from 1995 to 1999. Had these predators remained in Yellowstone Lake they would have consumed an estimated 23 metric tons of cutthroat trout (200 000 fish) during 1999 alone. If left unchecked, lake trout would clearly pose a serious threat to the long-term existence of the indigenous cutthroat trout. This analysis demonstrates the negative impact of an introduced predator in an ecologically isolated aquatic ecosystem.
Download or read book Distribution Movements and Life history Characteristics of Yellowstone Cutthroat Trout Oncorhynchus Clarkii Bouvieri in the Upper Yellowstone River Drainage written by Brian Daniel Ertel and published by . This book was released on 2011 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distribution and abundance of Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri, has declined across the historic range because of anthropogenic influences. Habitat has been fragmented and non-native species have been introduced that compete with, feed upon, or interbreed with cutthroat trout. As a result, many cutthroat trout populations are now isolated in headwater streams and life-history forms are lost or reduced. The upper Yellowstone River basin, above Yellowstone Lake, offers a rare opportunity to study Yellowstone cutthroat trout in a large, intact, river system with few anthropogenic influences. Understanding of life-history forms present in the upper Yellowstone River basin assist in proper conservation and management of the watershed. To determine cutthroat trout life-history forms present, their abundance, and habitat preferences, a combination of radio-telemetry, electrofishing, underwater census, habitat assessment, and age and growth were used. Movements of 151 cutthroat trout were tracked by aircraft, 2003-2005. Most relocated fish (98%) followed a lacustrine-adfluvial life history migration pattern, spending an average 24 days in the river. Cutthroat began entering the river in April and most emigrated by August. Fish migrated as far as 67 km to spawn and spawning aggregations within the system were found in only 11 locations. Underwater census and electrofishing surveys were used to determine fish distribution and abundance in the Yellowstone River and its tributaries. Main stem cutthroat trout densities were low and not evenly distributed. A mean of 8 fish/500 m reach were sampled with the majority in 8 reaches. Juvenile (150 mm, 2 years old) and large adult (330 mm,4 years old) cutthroat trout were found in the main stem, but fish from 151-330 mm (age 3) were absent. Within tributaries, fish densities ranged from 1.7-49.5 fish/100 m reach. Fish up to 305 mm were sampled and ranged 1 to 4 years in age. Data from this study suggest most cutthroat trout in the upper Yellowstone River express a lacustrine-adfluvial life history, however, some fluvial fish are present in tributaries. These findings will be important in driving conservation and management decisions in this drainage and provide critical information in future ESA listing considerations.
Download or read book Demography of Lake Trout in Relation to Population Suppression in Yellowstone Lake Yellowstone National Park written by John Michael Syslo and published by . This book was released on 2010 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduced lake trout Salvelinus namaycush threaten to extirpate native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri in Yellowstone Lake, Yellowstone National Park. Suppression of the lake trout population is deemed necessary for the conservation of Yellowstone cutthroat trout. A National Park Service gill netting program removed nearly 273,000 lake trout from Yellowstone Lake between 1995 and 2007. Lake trout population size has not been estimated; therefore, it is difficult to determine the efficacy of the program (i.e., proportion of the population that has been removed). My objectives were to (1) examine catch per unit effort (C/f) through time and catch as a function of effort to determine if the suppression program has caused lake trout abundance to decline, (2) determine if length structure, age structure, individual growth, mortality, body condition, length at maturity, age at maturity, and fecundity have changed as a function of harvest, and (3) develop age-structured models to determine the level of mortality required to cause population growth rate to decline below 1.0 (replacement). An increase in lake trout abundance was indicated by increasing C/f over time. Additionally, catch has continued to increase as a function of effort, indicating lake trout abundance is increasing. Population metrics were not clearly indicative of a response to harvest. However, metrics were comparable to North American lake trout populations where harvest has occurred, indicating that lake trout have not reached carrying capacity in Yellowstone Lake. Results from an age-structured matrix model determined the rate of population growth was 1.1 given the current rate of fishing mortality and that population growth rate would be 1.3 in the absence of fishing mortality. The current rate of population growth is positive; however, it is slower than it would be in the absence of lake trout suppression. Fishing mortality needs to increase from the rate of 0.22 estimated in 2007 to at least 0.32 to reduce population growth rate below replacement. Lake trout suppression is becoming an increasingly common management practice throughout the Intermountain West. Thus, Yellowstone Lake provides a case study for evaluating a strategy to remove the apex predator from a large lake.
