Patterns Of Natural Selection And Demography In Coastal Oregon Coho Salmon Oncorhynchus Kisutch Populations

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Patterns of Natural Selection and Demography in Coastal Oregon Coho Salmon (Oncorhynchus Kisutch) Populations

Author : Marc Aaron Johnson
Publisher :
ISBN 13 :
Total Pages : 222 pages
Book Rating : 4.:/5 (326 download)

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Book Synopsis Patterns of Natural Selection and Demography in Coastal Oregon Coho Salmon (Oncorhynchus Kisutch) Populations by : Marc Aaron Johnson

Download or read book Patterns of Natural Selection and Demography in Coastal Oregon Coho Salmon (Oncorhynchus Kisutch) Populations written by Marc Aaron Johnson and published by . This book was released on 2009 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: For Pacific salmon, the evolution of local adaptations depends upon the species' propensity to return, or "home", to natal streams at time of reproduction. Pacific salmon use olfactory cues to guide homing behavior, yet little is known about the genetics of olfaction in salmon. In this study, I use putatively neutral microsatellite markers to estimate demographic parameters and describe the population genetic structure of Oregon Coastal coho salmon (Oncorhynchus kisutch). Microsatellite analyses indicated weak population structure among coho populations (overall [theta] = 0.021), modulated by moderate levels of migration (straying). Allelic richness was higher in wild populations than both hatchery populations and wild populations from lake dominated systems. The Coos and Nehalem river populations appeared to be primary migrant sources, possibly elevating allelic richness for central coast populations. I then used genomic sequence data from nine species of salmon and trout to infer the evolutionary history for eight olfactory receptor genes, representing two major gene classes (main olfactory receptors and ORAs). Through a maximum likelihood based analysis of site-specific, non-synonymous to synonymous nucleotide substitution rates, I found strong evidence for positive selection having influenced the diversification of four paralogous main olfactory receptor genes. Main olfactory receptor orthologues appeared highly conserved among species, yet site-specific positive selection may be affecting interspecific divergence of an ORA gene in salmonids. Finally, I used molecular markers linked to olfactory receptor genes to test for a signal of selection among coho salmon populations from different rivers. By examining interlocus variance of F[subscript]ST, I found evidence for directional selection on an olfactory receptor gene-linked marker in coho salmon populations. Pairwise [theta] values calculated from gene-linked markers were nearly an order of magnitude greater than observed for putatively neutral microsatellites.

Population Dynamics of the Coho Salmon and Its Response to Logging in Three Coastal Streams

Author : David Wah Kwai Au
Publisher :
ISBN 13 :
Total Pages : 490 pages
Book Rating : 4.:/5 (817 download)

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Book Synopsis Population Dynamics of the Coho Salmon and Its Response to Logging in Three Coastal Streams by : David Wah Kwai Au

Download or read book Population Dynamics of the Coho Salmon and Its Response to Logging in Three Coastal Streams written by David Wah Kwai Au and published by . This book was released on 1972 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study examines the ecology and dynamics of coho salmon (Oncorhynchus kisutch) in environments experimentally altered by logging. The objective was to evaluate processes that stabilize or regulate the populations. Two small watersheds in Oregon's Coast Range were logged in 1966, one clear-cut, the other patch-cut. A third adjacent watershed was left uncut as a control. The influence of these treatments on the biology of the coho was assessed. Attention was concentrated on populations of the six year classes 1963 to 1968. The natural variability of streamflow-related conditions influencing both the magnitude and pattern of coho recruitment each year was increased in the logged watersheds. Peak flow during storms increased; intragravel dissolved oxygen levels decreased in the stream draining the clear-cut watershed. These changes, however, were apparently within the range of variation that the coho naturally experience. Increased stream temperatures and mortalities, due to the logging effects, altered the post-recruitment life conditions of the coho in that stream but did not significantly affect the final smolt yield. The nocturnal behavior of recently emerged fry leads to recruitment along the stream length. Fry tend to emerge en masse from the redds at night, and large numbers proceed immediately to disperse downstream. This migration continues for several successive nights, beginning each night soon after dark. Evidence is presented indicating that fry emigration is primarily a dispersal mechanism that distributes fry from redd sites to nursery areas. It is hypothesized that the series of events leading from fry dispersal to be quiescent behavior at night, characteristic of resident fry, is a developmental sequence involving the physiology and maturity of the fry, modified by agonistic activity. Adjustments in coho population size were largely accomplished by fall, resulting in stable and characteristic population levels in each stream. A stable smolt yield was a further result. These adjustments are accomplished through high mortality during the months of the first spring and summer. This mortality is likely density dependent and related to the territorial and agonistic behavior of the fish. Growth, biomass, and net production varied greatly during each year. Seasonal changes in growth rate resulted in seasonal variations in biomass that were in contrast to the stabilized trends of population number. The pattern of net production rate was also largely determined by the seasonal growth pattern, and like biomass, did not show: a tendency to stabilize with time. It averaged 5 g/m2 among the three streams for the period June 1 to April 15. The coho populations seem naturally regulated most importantly with respect to number. The patterns of biomass and rate of net production may be understood as an interaction of seasonally variable growth rate with stabilizing population numbers. This study has shown that coho streams normally produce characteristic levels of smolt yield in spite of large natural variations in fry input and conditions for growth. The range of environmental variation for which this result holds may include short-term changes due to logging. However a normal population response to such a severe alteration as occurred on Needle Branch is very likely conditional upon a program that at least includes vigorous stream clearance, the restriction of additional mortality to early summer, when population adjustments are far from complete, and the encouragement of streamside revegetation. A streamside buffer strip of trees is an effective way of protecting aquatic resources.

Endangered and Threatened Species ; Threatened Status for Southern Oregon/Northern California Coast Evolutionarily Significant Unit (ESU) of Coho Salmon

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Author :
Publisher :
ISBN 13 :
Total Pages : 122 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Endangered and Threatened Species ; Threatened Status for Southern Oregon/Northern California Coast Evolutionarily Significant Unit (ESU) of Coho Salmon by :

Download or read book Endangered and Threatened Species ; Threatened Status for Southern Oregon/Northern California Coast Evolutionarily Significant Unit (ESU) of Coho Salmon written by and published by . This book was released on 1997 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Genetic Variability in Hatchery and Wild Populations of Coho Salmon Oncorhynchus Kisutch in Oregon

Author : Paul Gordon Olin
Publisher :
ISBN 13 :
Total Pages : 176 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Genetic Variability in Hatchery and Wild Populations of Coho Salmon Oncorhynchus Kisutch in Oregon by : Paul Gordon Olin

Download or read book Genetic Variability in Hatchery and Wild Populations of Coho Salmon Oncorhynchus Kisutch in Oregon written by Paul Gordon Olin and published by . This book was released on 1984 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Microevolution, Local Adaptation, and Demography in Wild Populations of Pacific Salmon

Author : Jocelyn Lin
Publisher :
ISBN 13 :
Total Pages : 245 pages
Book Rating : 4.:/5 (821 download)

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Book Synopsis Microevolution, Local Adaptation, and Demography in Wild Populations of Pacific Salmon by : Jocelyn Lin

Download or read book Microevolution, Local Adaptation, and Demography in Wild Populations of Pacific Salmon written by Jocelyn Lin and published by . This book was released on 2012 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is increasing scientific interest in empirically linking evolution to ecology, particularly in wild populations. Although evolutionary change is often thought to proceed slowly, the microevolutionary forces of selection, gene flow, genetic drift and inbreeding can have pronounced effects on genetic variation even on short time scales. These genetic changes may then influence local adaptation and demography. The overarching aim of this dissertation was to estimate levels of gene flow and selection in wild populations, and to assess how microevolutionary change might affect local adaptation and population dynamics within these populations. Pacific salmon (Oncorhynchus spp.) are an ideal model organism for studying natural patterns of microevolution and local adaptation. First there is high phenotypic variation within the species, and spawning fish can be sampled comprehensively by capturing adults when they return to freshwater from the ocean. Second, salmon form reproductively isolated spawning populations due to natal homing, but these populations can be genetically and demographically connected via straying. Third, salmon are of ecological and commercial interest, making our findings relevant to population management. This dissertation investigated ecology and evolution in salmon as follows. In Chapter 1, we examined patterns of genetic and phenotypic differentiation between adjacent populations of beach and stream spawning ecotypes of sockeye salmon, and assessed potential levels of gene flow between ecotypes. The objective of Chapter 2 was to determine whether small populations of Chinook and chum salmon occurring in the Wood River system are reproductively isolated, self-sustaining populations, population sinks that produce returning adults but receive immigration, or strays from other systems that do not produce returning adults. In Chapter 3 we re-constructed pedigrees for two wild populations of sockeye salmon to estimate natural selection and heritability for several phenotypic traits. For Chapter 4, we used empirical results from the first three chapters to develop a stochastic, individual-based model that we used to study effects of gene flow and selection on local adaptation and population dynamics in interconnected salmon populations. Taken together, these studies showed how gene flow and selection affect local adaptation and demography in wild salmon populations.

Identification of Historical Populations of Coho Salmon (Oncorhynchus Kisutch) in the Oregon Coast Evolutionarily Significant Unit

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Author : Peter Wayne Lawson
Publisher :
ISBN 13 :
Total Pages : 129 pages
Book Rating : 4.:/5 (575 download)

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Book Synopsis Identification of Historical Populations of Coho Salmon (Oncorhynchus Kisutch) in the Oregon Coast Evolutionarily Significant Unit by : Peter Wayne Lawson

Download or read book Identification of Historical Populations of Coho Salmon (Oncorhynchus Kisutch) in the Oregon Coast Evolutionarily Significant Unit written by Peter Wayne Lawson and published by . This book was released on 2007 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Partial Migration of Puget Sound Coho Salmon (Oncorhynchus Kisutch) Individual and Population Level Patterns

Author : Jessica A. Rohde
Publisher :
ISBN 13 :
Total Pages : 88 pages
Book Rating : 4.:/5 (881 download)

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Book Synopsis Partial Migration of Puget Sound Coho Salmon (Oncorhynchus Kisutch) Individual and Population Level Patterns by : Jessica A. Rohde

Download or read book Partial Migration of Puget Sound Coho Salmon (Oncorhynchus Kisutch) Individual and Population Level Patterns written by Jessica A. Rohde and published by . This book was released on 2013 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Partial migration, the behavior pattern in which a portion of a population migrates while others do not, is a widespread phenomenon with ecological and evolutionary consequences. Most Coho Salmon (Oncorhynchus kisutch) from streams in the Puget Sound, Washington basin rear over the continental shelf or offshore waters of the North Pacific Ocean after leaving fresh water, but some rear in the semi-estuarine waters of Puget Sound and are termed residents.The movements of residents are poorly documented and it is unclear whether they ever leave Puget Sound and move to the coast of Washington, and what factors might influence fish to adopt a resident migration pattern. To understand this migration pattern at the population level, we used coded-wire tag data to evaluate the effect of several factors on the tendency of Coho Salmon to remain resident in Puget Sound rather than migrating outside, and on catch location within Puget Sound. We found that location of origin, day of release, and year of release most strongly affected residency, with fish released later and from south Puget Sound the most likely to remain resident. These factors together indicate that environmental variation plays a strong role in resident migration pattern. Additionally, fish remaining resident were more likely to be recovered in the basin they were released from than in neighboring basins.To understand this migration pattern at the individual level, we investigated the patterns of movement by resident Coho Salmon in Puget Sound at a series of spatial scales using acoustic telemetry. Some residents were detected departing Puget Sound, though they rarely moved between the different basins of Puget Sound. Additionally there was strong evidence of movement to deep, offshore environments during day, and shallow, close to shore environments at night. Rather than a discrete behavior, we suggest that residence in Puget Sound by Coho Salmon is part of a continuum of migratory behavior patterns.

Regions to Streams

Author : Rebecca L. Flitcroft
Publisher :
ISBN 13 :
Total Pages : 378 pages
Book Rating : 4.:/5 (182 download)

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Book Synopsis Regions to Streams by : Rebecca L. Flitcroft

Download or read book Regions to Streams written by Rebecca L. Flitcroft and published by . This book was released on 2008 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aquatic ecological investigation is expanding to encompass considerations of multiple scales across large landscapes. Much of the analysis included in this work focuses specifically on coho salmon (Oncorhynchus kisutch) in multiple subbasins on the Oregon coast. Coho salmon were chosen for an investigation of spatial scales, network connections, and life history stages due to their broad distribution on the Oregon coast, and abundant data describing their distribution, habitat needs, behavior, and survival. Chapter 2 introduces dynamic network topology (DNT) as a framework for analysis and interpretation of aquatic obligate species. DNT is based on the premise that in-stream habitats change in form and organization over time, and native aquatic species are adapted to those changes through movement and life history diversity. Chapter 3 analyzes juvenile coho salmon density and stream network occupancy at three spatial scales (site, patch, and subbasin). The site scale analysis indicated that combining network and traditional in-stream habitat metrics (i.e., substrate and habitat juxtaposition variables) are most effective at describing juvenile coho salmon density. Patch sizes of juvenile coho salmon were defined using variograms. Variogram shape indicated that a nested spatial structure may be present in larger subbasins, indicating overlapping patterns of juvenile stream use. At the subbasin scale, stream network occupancy by juvenile coho salmon was shown to vary over time within subbasins, and appeared to increase or decrease similarly to the size of the adult spawning run. In chapter 3, two-tier Bayesian hierarchical models were applied to adult (subbasin and basin scales) and juvenile (site and subbasin scales) coho salmon in an attempt to combine spatial scales that might be influential at each life history stage. The best fitting adult model included the percent of large trees in the riparian zone at the subbasin scale with mean annual precipitation at the basin scale. The best fitting juvenile model included three variables, percent sand, stream order, and network distance to spawning habitat which mirrors the result of modeling efforts in Chapter 3. Multiple spatial scales and the framework of a stream network were informative at detecting patterns and interactions among scales and life history stages of coho salmon.

Population Assessment-- Oregon Coast Coho Salmon ESU

Author : Thomas E. Nickelson
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (472 download)

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Book Synopsis Population Assessment-- Oregon Coast Coho Salmon ESU by : Thomas E. Nickelson

Download or read book Population Assessment-- Oregon Coast Coho Salmon ESU written by Thomas E. Nickelson and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Estimates of the Historical Abundance of Coho Salmon, Oncorhynchus Kisutch (Walbaum), in Oregon Coastal Streams and in the Oregon Production Index Area

Download Estimates of the Historical Abundance of Coho Salmon, Oncorhynchus Kisutch (Walbaum), in Oregon Coastal Streams and in the Oregon Production Index Area PDF Online Free

Author : Robert E. Mullen
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (95 download)

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Book Synopsis Estimates of the Historical Abundance of Coho Salmon, Oncorhynchus Kisutch (Walbaum), in Oregon Coastal Streams and in the Oregon Production Index Area by : Robert E. Mullen

Download or read book Estimates of the Historical Abundance of Coho Salmon, Oncorhynchus Kisutch (Walbaum), in Oregon Coastal Streams and in the Oregon Production Index Area written by Robert E. Mullen and published by . This book was released on 1981 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

A Landscape Approach to Determining and Predicting Juvenile Coho Salmon (Oncorhynchus Kisutch) Movement Timing and Growth Patterns Prior to Ocean Entry

Download A Landscape Approach to Determining and Predicting Juvenile Coho Salmon (Oncorhynchus Kisutch) Movement Timing and Growth Patterns Prior to Ocean Entry PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 124 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis A Landscape Approach to Determining and Predicting Juvenile Coho Salmon (Oncorhynchus Kisutch) Movement Timing and Growth Patterns Prior to Ocean Entry by :

Download or read book A Landscape Approach to Determining and Predicting Juvenile Coho Salmon (Oncorhynchus Kisutch) Movement Timing and Growth Patterns Prior to Ocean Entry written by and published by . This book was released on 2016 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coho salmon (Oncorhynchus kisutch) rely on unique habitats during the winter season, which may dictate how much individuals may growth and when migration from freshwater rearing habitat to the ocean occurs. Here I analyze movement timing and growth patterns for coho salmon through a field-based study and a literature review. For the field portion, I examined hatchery-stocked juvenile coho salmon across four stream basins in the Russian River watershed, California to determine the relative importance of climate, landscape, and fish size metrics in predicting movement and growth patterns over a winter rearing and spring smolt outmigration time period (December 2014-June 2015). I observed three unique movement strategies: winter parr movement, spring smolt movement, and inter-tributary movement. Movement was predicted in relation to daily temperature and precipitation, followed by in-stream and upslope basin conditions in random forest modeling. Specifically, fish that moved later were associated with basins that contained higher productivity and low-gradient floodplain habitats, while fish that moved earlier came from streams that lacked invertebrate prey and had limited low-gradient rearing habitat. Fish size and timing of movement were the primary predictors of growth, with relatively larger fish in the spring growing faster than fish that were relatively smaller prior to winter. These relationships suggest that hatchery-release fish are still highly influenced by environmental conditions once released, especially in terms of initial seasonal movement, and that watershed conditions should be considered when utilizing hatchery-rearing programs to supplement wild fish populations. In North America, coho salmon populations are distributed from Alaska through California, and may exhibit unique movement and growth patterns in relationship to population-scale vulnerability (Endangered Species Act listing), basin area, and availability and types of rearing habitat. For the second part of my thesis, I conducted a literature review to assess what factors are commonly considered in predicting movement and growth patterns for these fish, as well as the types (season and life stage) and number of movement strategies reported. Eighteen studies were summarized, of which sixteen identified unique movement strategies, ranging from one to four. Despite a wide range of basin areas and latitudes, winter parr and spring smolt movements were commonly observed, with authors primarily relating these behaviors to in-stream habitat and fish size metrics. Additionally, growth was linked positively and primarily with off-channel winter rearing, which may outweigh the importance of fish size in predicting growth when high quality rearing habitats are available during the winter season. Recognizing movement timing diversity and its drivers can help recover threatened coho salmon populations. More widely distributed populations may have unique phenotypic expressions based on localized genetic and environmental interactions, increasing diversity and overall stability across the population, a concept known as the portfolio effect. Understanding fish-habitat relationships can aid recovery efforts by providing a framework of climatic and watershed conditions that support unique behaviors, even in already severely limited populations.

Canadian Journal of Fisheries and Aquatic Sciences

Author :
Publisher :
ISBN 13 :
Total Pages : 738 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Canadian Journal of Fisheries and Aquatic Sciences by :

Download or read book Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2014 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Microevolution Rate, Pattern, Process

Author : Andrew P. Hendry
Publisher : Springer Science & Business Media
ISBN 13 : 9401005850
Total Pages : 528 pages
Book Rating : 4.4/5 (1 download)

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Book Synopsis Microevolution Rate, Pattern, Process by : Andrew P. Hendry

Download or read book Microevolution Rate, Pattern, Process written by Andrew P. Hendry and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: From guppies to Galapagos finches and from adaptive landscapes to haldanes, this compilation of contributed works provides reviews, perspectives, theoretical models, statistical developments, and empirical demonstrations exploring the tempo and mode of microevolution on contemporary to geological time scales. New developments, and reviews, of classic and novel empirical systems demonstrate the strength and diversity of evolutionary processes producing biodiversity within species. Perspectives and theoretical insights expand these empirical observations to explore patterns and mechanisms of microevolution, methods for its quantification, and implications for the evolution of biodiversity on other scales. This diverse assemblage of manuscripts is aimed at professionals, graduate students, and advanced undergraduates who desire a timely synthesis of current knowledge, an illustration of exciting new directions, and a springboard for future investigations in the study of microevolution in the wild.

Biochemical Genetic Variation Among Selected Populations of Chinook Salmon (Oncorhynchus Tshawytscha) in Oregon and Washington

Author : Anne Christine Kristiansson
Publisher :
ISBN 13 :
Total Pages : 58 pages
Book Rating : 4.:/5 (957 download)

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Book Synopsis Biochemical Genetic Variation Among Selected Populations of Chinook Salmon (Oncorhynchus Tshawytscha) in Oregon and Washington by : Anne Christine Kristiansson

Download or read book Biochemical Genetic Variation Among Selected Populations of Chinook Salmon (Oncorhynchus Tshawytscha) in Oregon and Washington written by Anne Christine Kristiansson and published by . This book was released on 1975 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biochemical variation in 12 different chinook populations, sampled from 10 hatcheries along the Columbia River and the Oregon coast, was studied with starch gel electrophoresis. An index was used to describe the genetic differences between pairs of populations. Differences were observed between spring and fall chinook and between Columbia River and Oregon coastal populations. Variation in inbreeding coefficients, calculated at four polymorphic loci, indicated that natural selection may alter the frequency of certain phenotypes.

Juvenile Coho Salmon (Oncorhynchus Kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon

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Author : Kailan F. Mackereth
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.:/5 (946 download)

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Book Synopsis Juvenile Coho Salmon (Oncorhynchus Kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon by : Kailan F. Mackereth

Download or read book Juvenile Coho Salmon (Oncorhynchus Kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon written by Kailan F. Mackereth and published by . This book was released on 2016 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Loss of lowland estuarine and freshwater off-channel habitats along the Pacific Northwest coast has contributed to the decline of salmonid populations. These habitats serve as nursery grounds for juvenile salmonids providing them with food, winter shelter, and a transition zone between freshwater and saltwater. Lowland areas have undergone anthropogenic alterations (e.g., installation of tide gates, construction of dikes, channelization) to increase the net area of land suitable for agriculture and development resulting in watershed fragmentation and reduction in the amount of habitats with high intrinsic potential to support populations of juvenile salmonids. Until recent years, sub-yearling coho salmon found in lowland riverine habitats and estuarine marshes were assumed to have been displaced from optimal upland reaches by competition and high water discharge. Recent studies have concluded that early estuarine migrant behavior is volitional and these fish return as 20-40% of the spawning population, but there are few studies that delve into the capacity of estuarine habitat to support early estuarine life history strategies in systems heavily altered by human practices. This study documented differences in diet and condition factor (K) between sub-yearling and yearling coho salmon foraging concurrently in brackish or freshwater lowland habitat of the upper estuarine intertidal zone. Fish stomach contents were sampled by means of gastric lavage in three coastal lowland creeks in Coos Bay on the southern Oregon coast. Prey found in the samples were sorted, counted, identified, and dried to obtain dry weight biomass. Condition factor (K) and total dry weight prey biomass of fishes were not different between brackish and freshwater habitat; however, non-metric multidimensional scaling indicated that prey composition was substantially different between habitat and age class. These findings suggest that early migrating sub-yearlings and yearling smolts diverge in their diets whether they occupy the same or different habitats in the stream to estuary transition zone. Insects were important prey within the diets of yearling and sub-yearling freshwater foragers and sub-yearling brackish water foragers while crustaceans were important in the diets of yearling brackish water foragers. Future research exploring prey abundance and availability in relation to prey selected by juvenile coho salmon would denote habitat foraging quality and habitat exploitation by early estuarine migrants. Expanding this research to contrast natural intertidal habitats with those regulated by tide gates would be beneficial towards understanding the impact different styles of tide gates have on biotic communities and hydrological attributes (e.g., flow, chemistry, temperature, tidal exchange). Identification of factors that influence habitat selection in the stream-estuary ecotone by alternative early life history strategies of juvenile coho salmon is essential towards enhancing genetic diversity thereby strengthening the resiliency of the population.

Improvement of Methods Used to Estimate the Spawning Escapement of Oregon Coastal Natural Coho Salmon

Author : Steven E. Jacobs
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (394 download)

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Book Synopsis Improvement of Methods Used to Estimate the Spawning Escapement of Oregon Coastal Natural Coho Salmon by : Steven E. Jacobs

Download or read book Improvement of Methods Used to Estimate the Spawning Escapement of Oregon Coastal Natural Coho Salmon written by Steven E. Jacobs and published by . This book was released on 1994 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Improving the Use and Assessment of State-space Models of Population Dynamics

Author : Sam McKechnie
Publisher :
ISBN 13 :
Total Pages : 220 pages
Book Rating : 4.:/5 (876 download)

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Book Synopsis Improving the Use and Assessment of State-space Models of Population Dynamics by : Sam McKechnie

Download or read book Improving the Use and Assessment of State-space Models of Population Dynamics written by Sam McKechnie and published by . This book was released on 2013 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Use of state-space modeling for stock assessments of salmon population dynamics has been limited compared to other fish and wildlife species, and this thesis aims to facilitate their application by investigating advantages of this approach, and resolving some methodological limitations. Other extensions such as the inclusion of abundance data from multiple stage-classes that have seldom been considered previously are also developed. A case study is explored where state-space, stage-structured models (`life-history models') are fitted to coho salmon data, and advantages over traditional models are investigated. Unfortunately, selecting among a set of candidate models can be di cult for state-space models owing to the technical nature of some model selection tools, and choices about which part/s of the model should be focused on. It is shown that currently used measures of data level deviance could be improved by use of partially-marginalized deviance measures that allow differences in process equations between candidate models to be detected. Whether the selected best model/s are adequate for inference is seldom assessed, or if it is, methodology is usually vague, and the power of detecting inadequacies has not been reliably assessed to date. It is shown that full assessment of model adequacy requires a partially marginalized extension of the more widely utilized posterior predictive checks (which are shown to have low power). Furthermore, the relative properties of test variables constructed based on different combinations of data and/or parameters/latent states are investigated. Finally, a significant limitation of state-space models in practice is the difficulty in ensuring all parameters in the model, and most notably the variance components parameters, are identifiable. Previous studies have attempted to constrain variance parameters by, for example, specifying the observation error variance as a constant after estimating sampling variation of the monitoring program that produced the abundance data. The latter technique was utilized herein, but before this was possible, methods for estimating the variance of spawner population size had to be developed. Novel estimators were developed to overcome this long-standing weakness of salmon monitoring programs, and a suite of estimators were compared in an extensive simulation study to determine the most robust methods to be applied when fitting state-space models to salmon data.