Changing Numbers Of Spawning Cutthroat Trout In Tributary Streams Of Yellowstone Lake And Estimates Of Grizzly Bears Visitings Streams From Dna

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Changing Numbers of Spawning Cutthroat Trout in Tributary Streams of Yellowstone Lake and Estimates of Grizzly Bears Visitings Streams from DNA

Author : Mark A. Haroldson
Publisher :
ISBN 13 :
Total Pages : 14 pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Changing Numbers of Spawning Cutthroat Trout in Tributary Streams of Yellowstone Lake and Estimates of Grizzly Bears Visitings Streams from DNA by : Mark A. Haroldson

Download or read book Changing Numbers of Spawning Cutthroat Trout in Tributary Streams of Yellowstone Lake and Estimates of Grizzly Bears Visitings Streams from DNA written by Mark A. Haroldson and published by . This book was released on 2005 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spawning Yellowstone cutthroat trout (Oncorhynchus clarki) provide a source of highly digestible energy for grizzly bears (Ursus arctos) that visit tributary streams to Yellowstone Lake during the spring and early summer. During 1985-87, research documented grizzly bears fishing on 61% of the 124 tributary streams to the lake. Using track measurements, it was estimated that a minimum of 44 grizzly bears fished those streams annually. During 1994, non-native lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake. Lake trout are efficient predators and have the potential to reduce the native cutthroat population and negatively impact terrestrial predators that use cutthroat trout as a food resource. In 1997, we began sampling a subset of streams (n = 25) from areas of Yellowstone Lake surveyed during the previous study to determine if changes in spawner numbers or bear use had occurred. Comparisons of peak numbers and duration suggested a considerable decline between study periods in streams in the West Thumb area of the lake. The apparent decline may be due to predation by lake trout. Indices of bear use also declined on West Thumb area streams. We used DNA from hair collected near spawning streams to estimate the minimum number of bears visiting the vicinity of spawning streams. Seventy-four individual bears were identified from 429 hair samples. The annual number of individuals detected ranged from 15 in 1997 to 33 in 2000. Seventy percent of genotypes identified were represented by more than 1 sample, but only 31% of bears were documented more than 1 year of the study. Sixty-two (84%) bears were only documented in 1 segment of the lake, whereas 12 (16%) were found in 2-3 lake segments. Twenty-seven bears were identified from hair collected at multiple streams. One bear was identified on 6 streams in 2 segments of the lake and during 3 years of the study. We used encounter histories derived from DNA and the Jolly-Seber procedure in Program MARK to produce annual estimates of grizzly bears visiting streams. Approximately 68 grizzly bears visited the vicinity of cutthroat trout spawning streams annually. Thus, approximately 14-21% of grizzly bears in the Greater Yellowstone Ecosystem (GYE) may have used this threatened food resource annually. Yellowstone National Park (YNP) is attempting to control the lake trout population in Yellowstone Lake; our results underscore the importance of that effort to grizzly bears.

Contrasting Past and Current Numbers of Bears Visiting Yellowstone Cutthroat Trout Streams

Author : Justin Everette Teisberg
Publisher :
ISBN 13 :
Total Pages : 10 pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Contrasting Past and Current Numbers of Bears Visiting Yellowstone Cutthroat Trout Streams by : Justin Everette Teisberg

Download or read book Contrasting Past and Current Numbers of Bears Visiting Yellowstone Cutthroat Trout Streams written by Justin Everette Teisberg and published by . This book was released on 2014 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spawning cutthroat trout (Oncorhynchus clarkii bouvieri) were historically abundant within tributary streams of Yellowstone Lake within Yellowstone National Park and were a highly digestible source of energy and protein for Yellowstone's grizzly bears (Ursus arctos) and black bears (U. americanus). The cutthroat trout population has subsequently declined since the introduction of non-native lake trout (Salvelinus namaycush), and in response to effects of drought and whirling disease (Myxobolus cerebralis). The trout population, duration of spawning runs, and indices of bear use of spawning streams had declined in some regions of the lake by 1997?2000. We initiated a 3-year study in 2007 to assess whether numbers of spawning fish, black bears, and grizzly bears within and alongside stream corridors had changed since 1997?2000. We estimated numbers of grizzly bears and black bears by first compiling encounter histories of individual bears visiting 48 hair-snag sites along 35 historically fished streams. We analyzed DNA encounter histories with Pradel-recruitment and Jolly-Seber (POPAN) capture-mark-recapture models. When compared to 1997?2000, the current number of spawning cutthroat trout per stream and the number of streams with cutthroat trout has decreased. We estimated that 48 (95% CI?=?42?56) male and 23 (95% CI?=?21?27) female grizzly bears visited the historically fished tributary streams during our study. In any 1-year, 46 to 59 independent grizzly bears (8?10% of estimated Greater Yellowstone Ecosystem population) visited these streams. When compared with estimates from the 1997 to 2000 study and adjusted for equal effort, the number of grizzly bears using the stream corridors decreased by 63%. Additionally, the number of black bears decreased between 64% and 84%. We also document an increased proportion of bears of both species visiting front-country (i.e., near human development) streams. With the recovery of cutthroat trout, we suggest bears that still reside within the Lake basin will readily use this high-quality food resource.

Yellowstone's Wildlife in Transition

Author : P. J. White
Publisher : Harvard University Press
ISBN 13 : 0674076419
Total Pages : 362 pages
Book Rating : 4.6/5 (74 download)

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Book Synopsis Yellowstone's Wildlife in Transition by : P. J. White

Download or read book Yellowstone's Wildlife in Transition written by P. J. White and published by Harvard University Press. This book was released on 2013-04-01 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The world's first national park is constantly changing. How we understand and respond to recent events putting species under stress will determine the future of ecosystems millions of years in the making. Marshaling expertise from over 30 contributors, Yellowstone's Wildlife in Transition examines three primary challenges to the park's ecology.

The Ecology of Large Mammals in Central Yellowstone

Author : Robert A. Garrott
Publisher : Academic Press
ISBN 13 : 0080921051
Total Pages : 712 pages
Book Rating : 4.0/5 (89 download)

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Book Synopsis The Ecology of Large Mammals in Central Yellowstone by : Robert A. Garrott

Download or read book The Ecology of Large Mammals in Central Yellowstone written by Robert A. Garrott and published by Academic Press. This book was released on 2008-11-25 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an authoritative work on the ecology of some of America's most iconic large mammals in a natural environment - and of the interplay between climate, landscape, and animals in the interior of the world's first and most famous national park.Central Yellowstone includes the range of one of the largest migratory populations of bison in North America as well as a unique elk herd that remains in the park year round. These populations live in a varied landscape with seasonal and often extreme patterns of climate and food abundance. The reintroduction of wolves into the park a decade ago resulted in scientific and public controversy about the effect of large predators on their prey, a debate closely examined in the book. Introductory chapters describe the geography, geology and vegetation of the ecosystem. The elk and bison are then introduced and their population ecology described both pre- and post– wolf introduction, enabling valuable insights into the demographic and behavioral consequences for their ungulate prey. Subsequent chapters describe the wildlife-human interactions and show how scientific research can inform the debate and policy issues surrounding winter recreation in Yellowstone. The book closes with a discussion of how this ecological knowledge can be used to educate the public, both about Yellowstone itself and about science, ecology and the environment in general. Yellowstone National Park exemplifies some of the currently most hotly debated and high-profile ecological, wildlife management, and environmental policy issues and this book will have broad appeal not only to academic ecologists, but also to natural resource students, managers, biologists, policy makers, administrators and the general public. - Unrivalled descriptions of ecological processes in a world famous ecosystem, based on information from 16 years of painstaking field work and collaborations among 66 scientists and technical experts and 15 graduate studies - Detailed studies of two charismatic North American herbivore species – elk and bison - Description of the restoration of wolves into central Yellowstone and their ecological interactions with their elk and bison prey - Illustrated with numerous evocative colour photographs and stunning maps

Wild Mammals of Wyoming and Yellowstone National Park

Author : Steven W. Buskirk
Publisher : Univ of California Press
ISBN 13 : 0520286898
Total Pages : 454 pages
Book Rating : 4.5/5 (22 download)

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Book Synopsis Wild Mammals of Wyoming and Yellowstone National Park by : Steven W. Buskirk

Download or read book Wild Mammals of Wyoming and Yellowstone National Park written by Steven W. Buskirk and published by Univ of California Press. This book was released on 2016-01-12 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wild Mammals of Wyoming and Yellowstone National Park provides the scholar, conservationist, and interested lay reader with information on the state's 117 wild mammalian species from grizzly bears to pygmy shrews. It describes the history of mammalogy in Wyoming, the zoogeography of Wyoming mammals, and the prehistoric mammals of Wyoming. It also characterizes the habitats of Wyoming mammals and addresses the conservation and management of mammals in the region. Expanding beyond the traditional field guide, Steven W. Buskirk emphasizes taxonomic classification, geographic range, and conservation status for mammalian species. Introductory sections are provided for each order and family, and individual species accounts organize a wealth of data ranging from habitat associations to field measurements in an easy-to-use format. Featuring color species photos, continental and state-scale distribution maps, and a comprehensive bibliography with nearly 1,000 references, Wild Mammals of Wyoming and Yellowstone National Park is an indispensable resource for wildlife and conservation biologists and mammalogists working in this region.

Yellowstone Science

Author :
Publisher :
ISBN 13 :
Total Pages : 402 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Yellowstone Science by :

Download or read book Yellowstone Science written by and published by . This book was released on 2005 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Canadian Journal of Zoology

Author :
Publisher :
ISBN 13 :
Total Pages : 408 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Canadian Journal of Zoology by :

Download or read book Canadian Journal of Zoology written by and published by . This book was released on 2014 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Noninvasive Survey Methods for Carnivores

Author : Robert A. Long
Publisher : Island Press
ISBN 13 : 1610911393
Total Pages : 399 pages
Book Rating : 4.6/5 (19 download)

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Book Synopsis Noninvasive Survey Methods for Carnivores by : Robert A. Long

Download or read book Noninvasive Survey Methods for Carnivores written by Robert A. Long and published by Island Press. This book was released on 2012-09-26 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: The status of many carnivore populations is of growing concern to scientists and conservationists, making the need for data pertaining to carnivore distribution, abundance, and habitat use ever more pressing. Recent developments in “noninvasive” research techniques—those that minimize disturbance to the animal being studied—have resulted in a greatly expanded toolbox for the wildlife practitioner. Presented in a straightforward and readable style, Noninvasive Survey Methods for Carnivores is a comprehensive guide for wildlife researchers who seek to conduct carnivore surveys using the most up-to-date scientific approaches. Twenty-five experts from throughout North America discuss strategies for implementing surveys across a broad range of habitats, providing input on survey design, sample collection, DNA and endocrine analyses, and data analysis. Photographs from the field, line drawings, and detailed case studies further illustrate on-the-ground application of the survey methods discussed. Coupled with cutting-edge laboratory and statistical techniques, which are also described in the book, noninvasive survey methods are effi cient and effective tools for sampling carnivore populations. Noninvasive Survey Methods for Carnivores allows practitioners to carefully evaluate a diversity of detection methods and to develop protocols specific to their survey objectives, study area, and species of interest. It is an essential resource for anyone interested in the study of carnivores, from scientists engaged in primary research to agencies or organizations requiring carnivore detection data to develop management or conservation plans.

Bear Use of Cutthroat Trout Spawning Streams in Yellowstone National Park

Author : Daniel Paul Reinhart
Publisher :
ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Bear Use of Cutthroat Trout Spawning Streams in Yellowstone National Park by : Daniel Paul Reinhart

Download or read book Bear Use of Cutthroat Trout Spawning Streams in Yellowstone National Park written by Daniel Paul Reinhart and published by . This book was released on 1989 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grizzly bears (Ursus arctos) and black bears (U. americanus) prey on spawning cutthroat trout (Oncorhynchus clarki, formerly known as Salmo clarki) in tributary streams of Yellowstone Lake. These tributary streams were surveyed from 1985 to 1987 to determine the presence and level of trout spawning activity and bear use. Indices were developed to enumerate spawner density and levels of bear use. Of 124 known tributaries of Yellowstone Lake, 48% had a spawning run. Of these spawning streams, 93% had associated bear activity, and 61% had associated evidence of bear fishing. Bears were apparently using more spawning streams and fish compared to 10 years earlier. Bear use of cutthroat trout spawning streams appeared to be largely a positive function of volumetric spawner density. We hypothesize that abundance and quality of stream-side vegetation relative to other foraging options influenced bear use. Intra- and interspecific avoidance among bears was suggested by patterns of spawning stream use. Less bear use of spawning streams than expected occurred within 1 km of park developments.

Status and Management of Interior Stocks of Cutthroat Trout

Author : Robert E. Gresswell
Publisher :
ISBN 13 :
Total Pages : 162 pages
Book Rating : 4.:/5 (45 download)

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Book Synopsis Status and Management of Interior Stocks of Cutthroat Trout by : Robert E. Gresswell

Download or read book Status and Management of Interior Stocks of Cutthroat Trout written by Robert E. Gresswell and published by . This book was released on 1988 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Mortality Studies on Cutthroat Trout in Yellowstone Lake [by] Orville P. Ball and Oliver B. Cope

Author : Orville P. Ball
Publisher :
ISBN 13 :
Total Pages : 72 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Mortality Studies on Cutthroat Trout in Yellowstone Lake [by] Orville P. Ball and Oliver B. Cope by : Orville P. Ball

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.

Predicting Year-class Abundance of Yellowstone Lake Cutthroat Trout

Author : Ross V. Bulkley
Publisher :
ISBN 13 :
Total Pages : 32 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Predicting Year-class Abundance of Yellowstone Lake Cutthroat Trout by : Ross V. Bulkley

Download or read book Predicting Year-class Abundance of Yellowstone Lake Cutthroat Trout written by Ross V. Bulkley and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluctuations in strength of year classes from 1945 to 1956 of Yellowstone Lake cutthroat from Pelican and Chipmunk Creeks are compared with the parental stock and several climatically influenced factors of the environment. Variations in year-class strength in the two tributaries were highly correlated with fluctuations in lake water levels. Strong year classes occurred in yeas of low water. Female spawner escapement, timing of the runs, and summer air temperatures were not significant factors. A formula based on water levels is presented for predicting year-class strength in Pelican Creek and in the Fishing Bridge area fishery. Stocking of fry in years of high water is suggested as a means of supplementing natural production. A method of forecasting lake water levels several months in advance of their occurrence is discussed.

Knowing Yellowstone

Author : Jerry Johnson
Publisher : Rowman & Littlefield
ISBN 13 : 1589795229
Total Pages : 185 pages
Book Rating : 4.5/5 (897 download)

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Book Synopsis Knowing Yellowstone by : Jerry Johnson

Download or read book Knowing Yellowstone written by Jerry Johnson and published by Rowman & Littlefield. This book was released on 2010-06-16 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Visitors to Yellowstone National Park are drawn to the spectacular scenery, unique thermal features, and the large numbers of wild animals easily observed in their natural habitat. The thoughtful visitor to the park cannot help but be captivated by the unparalleled breadth of scientific knowledge needed to understand the intricate interrelationships that make up the yellowstone landscape. Knowing Yellowstone explores how scientists discover what they know about America's first national park and the surrounding lands. The chapter authors are scientists who represent the best of their fields of study. The science they describe is leading the way to our understanding of complex ecosystems worldwide.

Yellowstone Grizzly Bears

Author : Daniel D. Bjornlie
Publisher : National Park Service Yellowstone National Park
ISBN 13 : 9780934948463
Total Pages : pages
Book Rating : 4.9/5 (484 download)

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Book Synopsis Yellowstone Grizzly Bears by : Daniel D. Bjornlie

Download or read book Yellowstone Grizzly Bears written by Daniel D. Bjornlie and published by National Park Service Yellowstone National Park. This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Life-history Organization of Cutthroat Trout in Yellowstone Lake and Its Management Implications

Author : Robert E. Gresswell
Publisher :
ISBN 13 :
Total Pages : 314 pages
Book Rating : 4.:/5 (364 download)

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Book Synopsis Life-history Organization of Cutthroat Trout in Yellowstone Lake and Its Management Implications by : Robert E. Gresswell

Download or read book Life-history Organization of Cutthroat Trout in Yellowstone Lake and Its Management Implications written by Robert E. Gresswell and published by . This book was released on 1994 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Life-history organization of the cutthroat trout (Oncorhvnchus clarki) may be viewed at various levels, including species, subspecies, metapopulation, population, or individual. Each level varies in spatial scale and temporal persistence, and components at each level continually change with changes in environment. Cutthroat trout are widely distributed throughout the western USA, and during its evolution the species has organized into fourteen subspecies with many different life-history characteristics and habitat requirements. Within subspecies, organization is equally complex. For example, life-history traits, such as average size and age, migration strategy, and migration timing, vary among individual spawning populations of Yellowstone cutthroat trout (Oncorhvnchus clarki bouvieri) in tributary streams of Yellowstone Lake. In this study specific life-history traits of adfluvial cutthroat trout spawners from Yellowstone Lake were examined in relation to habitat of tributary drainages and subbasins of the lake. Results suggest that stream drainages vary along gradients that can be described by mean aspect, mean elevation, and drainage size. Approximately two-thirds of the variation in the timing of annual cutthroat trout spawning migrations and average size of spawners can be described by third-degree polynomial regressions with mean aspect and elevation as predictor variables. Differences in average size and growth of cutthroat trout suggested metapopulation substructure related spatial heterogeneity of environmental characteristics of individual lake subbasins. Evidence that polytypic species can adapt to heterogenous environments, even within a single lake, has implications for the conservation, restoration, and management of many freshwater fishes. Understanding the consequences of human perturbations on life-history organization is critical for management of the cutthroat trout and other polytypic salmonid species. Loss of diversity at the any hierarchical level jeopardizes long-term ability of the species to adapt to changing environments, and it may also lead to increased fluctuations in abundance and yield and increase risk of extinction. Recent emphasis on a holistic view of natural systems and their management is associated with a growing appreciation of the role of human values in these systems. The recreational fishery for Yellowstone cutthroat trout in Yellowstone National Park is an example of the effects of management on a natural-cultural system. Although angler harvest has been drastically reduced or prohibited, the recreational value of Yellowstone cutthroat trout estimated by angling factors (e.g., landing rate or size) ranks above all other sport species in Yellowstone National Park. To maintain an indigenous fishery resource of this quality with hatchery propagation is not economically or technically feasible. Nonconsumptive uses of the Yellowstone cutthroat trout including fish-watching and intangible values, such as existence demand, provide additional support for protection of wild Yellowstone cutthroat trout populations. A management strategy that reduces resource extraction has provided a means to sustain a quality recreational fishery while enhancing values associated with the protection of natural systems.

Applied Investigations Into Grizzly and Black Bear Ecology and Management

Author : Justin Everette Teisberg
Publisher :
ISBN 13 : 9781267477323
Total Pages : pages
Book Rating : 4.4/5 (773 download)

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Book Synopsis Applied Investigations Into Grizzly and Black Bear Ecology and Management by : Justin Everette Teisberg

Download or read book Applied Investigations Into Grizzly and Black Bear Ecology and Management written by Justin Everette Teisberg and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the second Chapter, I investigated the genetic consequences of management actions and genetic introgression on black bears. Due to changing management philosophies and policies in Yellowstone National Park (YNP), large numbers of black bears were removed (13 to 30% of population per annum) from the core of the ecosystem between 1930 and 1970. Using ancient DNA (aDNA) extraction techniques on historic specimens, we investigated whether these removals influenced genetic diversity of black bears within the GYE. While Ne values were found to be historically low (Ne point estimates of 19--87) since the early years of the Park, we observed only slight decreases in all diversity measures before and after the large-scale removal of black bears, likely due to gene flow from outside demes. However, the strength of genetic drift following removals may have been much more substantial without this outside introgression.

Temporal Segregation in Spawning Between Yellowstone Cutthroat Trout and Rainbow Trout

Author : John Martin Fennell
Publisher :
ISBN 13 :
Total Pages : 152 pages
Book Rating : 4.5/5 (381 download)

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Book Synopsis Temporal Segregation in Spawning Between Yellowstone Cutthroat Trout and Rainbow Trout by : John Martin Fennell

Download or read book Temporal Segregation in Spawning Between Yellowstone Cutthroat Trout and Rainbow Trout written by John Martin Fennell and published by . This book was released on 2021 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Native cutthroat trout populations in western North America have faced substantial declines in part due to interactions with non-native species. One such interaction, hybridization with introduced rainbow trout, is recognized as one of the most pressing concerns facing native cutthroat trout populations. I explored how one mechanism of reproductive isolation, temporal segregation, may be limiting hybridization between Yellowstone cutthroat trout and rainbow trout in the North Fork Shoshone River drainage in northwest Wyoming. Using data on adult fish spawning migration timing paired with high resolution genomic data, we provide evidence that Yellowstone cutthroat trout spawn on average 2-4.5 weeks later in the drainage than both rainbow trout and Yellowstone cutthroat trout x rainbow trout hybrids (hybrids). Additional data collected on the size and ancestry of juvenile fish in study tributaries provides further evidence that Yellowstone cutthroat trout spawn later in the spawning season compared to rainbow trout and hybrids. I also investigated how changing water temperature and discharge in the drainage throughout the spawning season may explain differences in the timing of spawning migrations between Yellowstone cutthroat trout, rainbow trout, and hybrids. Yellowstone cutthroat trout were more likely to migrate into the spawning tributary on days after the seasonal peak in stream discharge and on days where water temperature stayed at or above 6 degrees Celsius longer. While Yellowstone cutthroat trout are entering spawning tributaries later, on average, than both rainbow trout and hybrids, disproportionately high numbers of rainbow trout and hybrids paired with extended spawning seasons leads to substantial overlap between when Yellowstone cutthroat trout, rainbow trout, and hybrids are spawning in the system. Thus, I conclude that while temporal segregation in spawn timing may play some role in the persistence of unadmixed Yellowstone cutthroat trout in the drainage, additional mechanisms of reproductive isolation likely exist between the two species.