The Willamette River, one of only 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of Willamette River fish detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (NP [NP], rivermile [RM] 26-55) and middle...
This research was designed to broaden the understanding of how timber-harvest affects aquatic macroinvertebrates in perennial and intermittent headwater streams. This study compared emergent and benthic macroinvertebrate assemblages from 20 headwater streams in the central Oregon Coast Range that varied by harvest condition and flow duration. Through comparison of the...
Island systems and species are susceptible to extinction because of their small population size and an ecological naiveté from an evolutionary past lacking strong competition and predation. For example, only one-fifth of the world’s bird species occur on islands, yet more than 90% of the avian extinctions witnessed during historic...
Previous research in South Fork Hinkle Creek suggested that coastal cutthroat trout exhibit an aggregated spatial pattern across multiple spatial scales. To evaluate the persistence of the observed abundance patterns and identify factors that affect those patterns, half-duplex passive integrated transponders (PIT-tags) were implanted in 320 coastal cutthroat trout (>...
Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may...
For the first objective of this thesis, we attempt to understand the role of water flow and directionality in determining steelhead (Oncorhynchus mykiss) and spring/summer and fall Chinook (O. tschawytscha) migration patterns within the Columbia River Estuary and plume by integrating recent advances in biotelemetry and environmental observation and forecasting...
Recent studies of headwater streams have demonstrated their importance to overall watershed biodiversity, nutrient cycling, and energy flux. However, little attention has been paid to long-term effects of forest harvest on macroinvertebrate communities in headwater streams. This study investigated headwater stream macroinvertebrate communities in the H.J. Andrews Experimental Forest, Oregon,...
Radiotelemetry was used to study the seasonal movements and habitat use of adult westslope cutthroat trout Oncorhynchus clarki lewisi in Roberts
Creek and Rail Creek, headwater tributaries of the John Day River, Oregon,
from September 2000 to December 2001. The objectives were to (1)
describe adult cutthroat trout life history...
I examined the avian biogeography of the islands of Lago Gatun, Panama, in an effort to better understand the effects of forest fragmentation in this biodiverse region, and specifically to understand the importance of fragment isolation and the mechanism behind its effects on tropical bird distribution. I combined exhaustive surveys...
North American sagebrush (Artemisia spp.) ecosystems are suffering from
reductions in habitat extent and quality. Only about 50% of sagebrush remains
from pre-settlement conditions, and much of the remaining habitat is
fragmented or degraded by invasive species, fire suppression and overgrazing.
Sagebrush-obligate species are experiencing population declines as a result...
I measured responses of free-ranging Rocky Mountain elk (Cervus elaphus) to recreational disturbance at Starkey Experimental Forest and Range, Oregon from April to October, 2003 and 2004. Resting, feeding, and travel activities of 13 cow elk were recorded at 5-minute intervals using Actiwatch™ motion sensors. Elk were subjected to four...
Rotifers and brine shrimp (Artemia) are important prey items for rearing marine fish larvae. Their availability in the water column may be reduced when they are transferred to larval rearing tanks at lower temperature. In this study, Brachionus rotundiformis (SS-type) and Brachionus plicatilis (L-type) were semi-continuously cultured and fed on...
An acceptable microparticulate diet for marine fish larvae may be defined as an artificial diet that contains, retains, and delivers the required nutrients to support survival and growth. Factors affecting ingestion rate of prey items by fish larvae include environmental factors such as light intensity, prey/background contrast, possible chemical cues,...
Pacific rockfishes (genus Sebastes) have attracted wide scientific and public interest from an evolutionary, fishery and conservation standpoints. This dissertation addresses several hypotheses involving spatial and temporal scales of genetic change in two overfished rockfishes, darkblotched (S. crameri) and canary rockfish (S. pinniger), using statistical analyses of genetic variation within...
Seabirds are an integral component of marine ecosystems, however, because humans typically observe only snapshots of their lives at sea, our understanding of seabird foraging ecology is often limited. A more complete understanding of the ecological roles of seabirds and identification of critical foraging habitats requires the ability to follow...
Salmonid run sizes are strongly affected by their early marine stage. Fully understanding the life history of salmonids means understanding how they interact with their marine environment and with other fishes. Changes in the biological and physical environment off the Columbia River region affects the distribution and abundance of predatory...
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
I studied small-mammal communities and their response to grazing in mixed-conifer forests and oak woodlands in the Cascade-Siskiyou National Monument in southern Oregon. My objectives were to (1) compare small-mammal communities among forest types and grazing intensities, (2) identify riparian affiliated species, and (3) describe microhabitat associations. Over two years,...
Chinook salmon (Oncorhynchus tshawytscha) display the greatest variability of return times to freshwater of all Pacific salmon. Differential return times to freshwater have segregated populations of Chinook into two broad types or runs, fall and spring, named for the time of year in which they migrate to freshwater. Migration time...
The Northern California Current (NCC) ecosystem exhibits extreme seasonal, interannual and interdecadal shifts in the abiotic environment and shifts in primary and higher production. This variability is also apparent in the spatial structure of the ecosystem with nearshore-shelf waters (<150 m isobath) being highly productive and having a different community...
The northern goshawk (Accipiter gentilis) is a species of concern in the western United States due to its association with mature structural stage forests. I employed a use-versus-availability study design to quantify the vegetative, physiographic, and landscape variables associated with goshawk breeding habitat selection in the San Juan Mountains of...
Riparian areas are eco-tones where aquatically- and terrestrially-derived insect biomass is exchanged between habitats, presenting consumers with new sources of energy, and resulting in a reciprocal subsidy. The relative contribution of energy exchange and the
resulting impacts on vertebrate riparian consumers, such as fish or birds, remains poorly understood. We...
Historically, least terns (Sterna antillarum) were one of the most common tern species in North America. However, population declines have resulted from direct and indirect anthropogenic pressures on their breeding and foraging habitat. Three subspecies of least terns have been described within the United States: California least tern (S. a....
Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation in landscape and in-stream conditions. The objectives of this study were to determine how landscape level topographic features influence LCT distribution patterns....
Riparian areas in the Pacific Northwest provide important biotic and abiotic
features, such as down wood, moist microsites, and abundant invertebrate prey that
benefit aquatic and terrestrial amphibians. Reported high densities of amphibians from
streams and riparian areas in the Pacific Northwest highlight their importance in riparian
food webs. Amphibians...
Anthropogenic land use alterations such as livestock grazing and fire
suppression have greatly altered sagebrush grasslands of the Great Basin,
facilitating invasion of exotic annuals, increases in woody species, and losses of
native species. Much of the current research surrounding wildland and prescribed
fire in sagebrush dominated ecosystems has focused...
Recently, there has been concern over the decline of the Pacific lamprey, Lampetra tridentata, in the northwestern United States. However, effective management has been impeded by data gaps in basic biology, especially in the early life stages. Consequently, in 2004 and 2005 I examined reproductive ecology, larval recruitment, and lamprey...
Low reproductive success has been typical of high elevation populations of the Hawaiian goose (Branta sandvicensis) or nēnē. Researchers identified predation and inadequate nutrition as limiting factors. Reproductive success remained low in most years despite on-going predator control programs. I used a supplemental feeding program over two breeding seasons in...
Larval transport and retention of two endangered suckers were studied in a highly
altered lacustrine/riverine complex. The endangered populations of Lost River sucker,
Deltistes luxatus, and shortnose sucker, Chasmistes brevirostris, in Upper Klamath Lake
(UKL), Oregon are the largest remnant populations of these suckers. Downstream of
UKL, the Keno Impoundment...
I studied developmental rates in a suite of temperate and tropical passerine bird species from the New World to test the hypothesis that tropical passerines exhibit slower patterns of growth and development than temperate birds. I also investigated how the expression of several developmental rates varied with life history traits...
Understanding seasonal changes in growth, survival, and movement rates is
crucial to salmonid management. These life history characteristics provide a context for
evaluation of management actions. We evaluated the life history of individually
marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in
Northeastern Oregon. This thesis...
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite...
Effective treatment of larval bacterial diseases is a difficult problem when
culturing ornamental fish. Oral administration of antibiotics using existing
microparticle types is not effective due to high leakage rates; furthermore, injection of
larvae is not practical. Treatment is currently limited to use of antibiotic baths, . In this
study,...
For many species of marine turtle the characteristics that define pelagic habitat have yet to be fully identified. A better understanding of these habitat characteristics is critical to reduce high seas fisheries interactions with turtles, especially as the status of many turtle populations has placed them on the threatened or...
The role of fire as a natural disturbance, its interactions with nonnative species and effects of repeated fires in the Hawaiian Islands have received little investigation. We are unsure of the role fire played in shaping forest structure and composition as well as affecting evolutionary processes of the native biota....
Wildfire is a largely terrestrial perturbation broadly recognized as an agent of disturbance and ecological change in forested biomes. Effects of post-fire conditions on biotic components of aquatic systems have been less well-documented, although hypothetically, the two are strongly connected. In fact, the influence of wildfire may be most profound...
Oregon's only remaining non-reservoir population of adfluvial bull trout (Salvelinus confluentus) is found in Odell Lake, in the headwaters of the Deschutes River. The population size is unknown, but appears to be quite small. Limited spawning and rearing habitats, combined with the effects of introduced species and other anthropogenic changes...
The potential for Rocky Mountain mule deer (Odocoileus hemionus hemionus)
to host exotic chewing lice (Damalinia (Cervicola) sp.) believed to cause deer hair
loss syndrome in Columbian black-tailed deer (Odocoileus hemionus columbianus),
was investigated in captive deer held in pens at E.E. Wilson Wildlife Area, Corvallis,
Oregon from March 2004...
I developed a priori hypotheses and used logistic regression to model Greater Sandhill
Crane (Grus canadensis tabida) nest success in relation to weather, habitat and management variables for cranes breeding at Malheur National Wildlife Refuge (MNWR) in southeast Oregon. My primary interest was to investigate the effects of habitat conditions...
Mark-recapture methods were used to examine watershed-scale survival rates of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks located in the foothills of the Cascade Mountain Range, Oregon. Differences in survival were explored among spatial (stream segment, stream network [main stem or tributaries], and watershed) and temporal...
Anadromous coastal cutthroat trout Oncorhynchus clarkii clarkii may be highly dependent on estuaries, passing through them multiple times during their lifetime. However, few studies have investigated estuarine use by coastal cutthroat trout and it is often thought that estuaries serve primarily as migration corridors rather than rearing areas. We used...
I used current water management practices in central and eastern Oregon and Washington as natural experiments to quantify the effects of irrigation water withdrawals on macroinvertebrate community structure and life history strategies. Reduced discharge had direct (e.g. decreased velocity and wetted habitat) and indirect (e.g. increased conductivity and temperature) effects...
Frequent or lengthy predation risk can cause one of two modifications of prey feeding
behavior: 1) postponement of feeding to less risky periods, or 2) resumption of feeding
behavior despite persistent risk. North Pacific flatfishes exhibit both of these responses when confronted with temporal variation in risk, and this experimental...
This study was designed to provide life history information about juvenile fall Chinook salmon, Oncorhynchus tshawytscha
(Walbaum), in a small coastal river by 1) documenting the length of residence of the juveniles throughout the river, 2) exploring several factors possibly influencing their length of residence, and 3) assessing the relative...
During the summers of 1970 and 1971 a total of 95 sea otter (Enhydra lutris) were shipped to Oregon from Amchitka Island, Alaska. The 1970 shipment consisted of 31 otter which were to be released on the southern Oregon Coast near the town of Port Orford. Two of these animals...
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...
Between 1970 and 1974, data were collected on the distribution and biology of the spotted owl (Strix occidentalis) in Oregon. One-hundred and sixteen pairs and seven single birds were located. Spotted owls occurred throughout the mountains of western Oregon and on the east slope of the Cascade Range at least...
The genetic basis of adaptation is complex as many fitness-related traits are quantitative and likely influenced by multiple genes with variable effects across different selective environments. One important adaptation for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which individuals return to natal breeding sites within a reproductive season....
Land use alters the physical and biological structure of stream ecosystems and potentially alters their capacity to process nitrogen (N), an essential nutrient that has nearly doubled in abundance on the biosphere
during the past century from human activities. In this dissertation, I quantified uptake and transformation of nitrate (NO₃⁻)...
Identification of critical habitat for all life stages of commercially exploited fish populations is critical for effective management. Despite a clear need for basic biological information on juvenile rockfish life history, there have been very few efforts to describe distribution and habitat of this life stage, particularly along the Oregon...
Populations of coastal cutthroat trout, Oncorhynchus clarki clarki, were sampled in 16 headwater streams from logged (20-30 and 40-60 years ago) and unlogged (stand age 125-150 years) basins. Basins logged 20-30 years ago supported the widest range of mean biomass of age 1+ or older cutthroat trout (g/m2) and the...
Under laboratory conditions, elevated temperatures accelerated production of gametes. However, when conditioning for spawning at elevated temperatures was
initiated early in the season (January-March), larval survival and number of spat collected were significantly lower than when conditioning was initiated in may or June. At elevated temperatures, broodstock oysters were fed...
Results of a study of spatial and temporal utilization of a tidal river estuary by hatchery and wild juvenile salmonids
(Oncorhynchus spp. and Salmo spp,), of overlap in food habits of hatchery and wild juvenile salmonids, and of size and relative
abundance of associated fish species are reported in this...
High severity fire is a historical and integral disturbance process in coniferous
forest types. Compounded disturbances such as multiple fires or post-disturbance
management activities are increasingly common, but ecological responses are not well
understood and may represent novel types of disturbances. I studied bird and small
mammal communities in the...
Models are commonly used to assess and predict wildlife response to management practices. Model validation is essential if managers are to use them with confidence. Fifteen forest bird-habitat relationship models were developed by biologists using data collected from private forestland in southwest Washington. These models predict species' probability of occurring...
Incidental bycatch in commercial fisheries has been identified as a threat to black-footed albatrosses (Phoebastria nigripes) and Laysan albatrosses (P. immutabilis). Effective long-term conservation of these albatrosses necessitates a thorough understanding of their marine distribution, which marine habitats are selected during foraging, and where they are most likely to interact...
Great Salt Lake (GSL), Utah, is surrounded by 191,884 hectares of wetlands. These wetlands provide critical habitat for hundreds of thousands of breeding, migrating and wintering waterfowl each year. As the human population around GSL increases, government officials have proposed to divert more water from the Jordan, Ogden, and Bear...
Riparian areas in the arid western United States are critical ecosystems that have been severely degraded by a variety of land and water uses over the last 100 years. In this study, the composition and structure of floodplain vegetation along the Lower Owens River in eastern California was quantitatively described...
This study was undertaken to determine if strontium chloride could be used to create a trans-generational otolith mark in steelhead (Oncorhynchus mykiss). I completed two strontium injection trials and a survey of juvenile steelhead from various steelhead hatcheries. The two trials measured Sr:Ca ratios in otoliths in response to injections...
Riparian vegetation (trees > 10 cm dbh), woody debris (> 10 cm diam, > 1 m long), channel, and landform characteristics were inventoried in mature (80-150 yrs) and old-growth riparian areas (>250 yrs) selected from small tributaries of the Coos and Coquille River basins in southwestern Oregon. Basal area of...
Northern anchovy (Engraulis mordax) are a dominant forage fish in the California Current large marine ecosystem (CCLME). However, little is known about northern anchovy abundance, distribution, age structure, or population fluctuations relative to ocean conditions in the eastern boundary upwelling system off the U.S. West Coast. This thesis includes three...
Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none...
The dissertation introduces community-based adaptive watershed management (CAWM) as a holistic conservation framework. The CAWM
framework integrates social and ecological suitability to achieve conservation outcomes. The core theoretical concepts consist of adaptive management, adoption-diffusion,
symbolic interactionism, community-based conservation, spatial analysis and watershed management. The CAWM framework is applied to the...
The overall goal of this study was to identify multiple scales of habitat use and habitat electivity by redband/steelhead trout and define the limiting factors affecting the distribution patterns of this species during summer flows.
The main objective in chapter 2 was to identify the most important habitat associations that...
A study conducted May 1978-December 1980 determined that the present geographic range of Columbian white-tailed deer, Odocoileus virginianus leucurus, (CWTD) in Douglas County, Oregon encompassed 1199km2. The area was predominately a Quercus woodland community, typical of the Interior Valley Zone of western Oregon. The CWTD distribution
was not contiguous throughout...
To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the...
In the fall and winter of 1965, 1966, and 1967, 298 ratfish (180 males, 118 females) were collected off the Pacific coast of
Oregon and Washington and examined for food habits , parasites, growth relationships and a method of age determination. The following
food organisms were found to be the...
Patterns of resource partitioning among 4 sympatric sturnids: [black-collared starling (Sturnus nigricollis), pied starling (S. contra), common myna (Acridotheres tristis) and crested myna (A. javanicus) were determined based on their food habits, foraging and nesting microhabitat selection, morphology and behavior. The study was
conducted from March 1986 to June 1988...
The functioning of marine habitats needs to be understood in the context of the ecological relationships and associations between organisms and the physical and biogenic environment they inhabit. Thus, it becomes important to explore and define habitat features which contribute to these relationships and which are important in the life...
I investigated survival, movements, home range sizes, and habitat selection of pygmy rabbits (Brachylagus idahoensis) in southeastern Oregon and northwestern Nevada from June 2005 to June 2007. I trapped 298 rabbits on four sites and fitted each with radio transmitters. More than 13,000 locations of telemetered rabbits were recorded. I...
The effects of sublethal concentrations of cyanide, pentachlorophenol and zinc individually and in combination on the growth and production of juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum), and aquatic invertebrates in model stream communities were studied in three experiments during 1971 and 1972 at the Oak Creek Fisheries Research Laboratory, Oregon...
The movements, habitat use, and activity patterns of black-tailed deer in western Oregon, and the influence of suburban housing developments on the behavior of deer in the area, were studied and described. Radio telemetry, spotlight censusing, and a resident questionnaire were used to document the behavior of deer. Radio telemetry...
Summer mortality of farmed Pacific oysters causes financial losses for shellfish growers, and selective breeding to improve survival of offspring is a promising way to reduce losses. This dissertation has two objectives to assist the development of tools for use in selective breeding programs.
Objective 1: Identify candidate genes for...
In this dissertation, new theory and its applications are developed to predict three properties of complex ecological communities: stability, equilibrium response, and non-equilibrium dynamics. First, a graph-theoretic analysis identifies the interconnections in a complex ecosystem that promote or diminish stability (Chapter 2). The hierarchy of interactions that influences stability and...
Greater sage-grouse (Centrocercus urophasianus), a sagebrush obligate species, has contracted in extent by nearly half its original distribution. This is primarily due to habitat loss and degradation over the past 150 years. During winter, sage-grouse depend completely on sagebrush habitat for food and cover, yet sage-grouse winter ecology has been...
Small low-head diversion dams are capable of removing much of the flow of a river, often resulting in increased water temperatures and habitat loss. Warmer temperatures have been shown to accelerate aquatic invertebrate growth and development, and discharge reductions can reduce instream habitat, suggesting that water withdrawals may alter both...
Over one third of the earth’s land surface has been modified to some extent for agricultural purposes. The large global footprint of agriculture, combined with the knowledge that existing reserve networks are likely insufficient for long-term conservation of native biodiversity, has necessitated that agricultural systems contribute to conservation of native...
Rates of defecation of black-tailed deer in the Tillamook Burn of western Oregon were estimated using counts of groups of fecal
pellets in 1959 and 1960. A 340-acre enclosure was divided into eight range types on the basis of depth of soil, aspect, and elevation. The estimated rates of defecation...
I examined the relative roles of biotic and abiotic factors in structuring redband trout
Oncorhynchus mykiss distributions in the South Fork John Day. I first examined the
relationship between the biological traits of the fish assemblage and riparian-geomorphic features in context of prevailing theories of stream ecology stemming from the...
The Double-crested Cormorant (Phalacrocorax auritus) is a widespread, colonial, North American waterbird with bicoastal and inland distributions. Four subspecies have been described within North America corresponding to five geographic breeding regions: Interior and North Atlantic cormorants (P. a. auritus); Southeastern cormorants (P. a. floridanus); Alaskan cormorants (P. a. cincinnatus); and...
The growth, size and age composition, mortality and reproduction of darkblotched rockfish (Sebastes crameri) were examined using fishery data and analysis of fish
characteristics for samples collected of f the Oregon coast. A total of 1060 fish, caught by commercial groundfish and shrimp trawlers operating out of Newport, Coos Bay...
Growth characteristics of otoliths were used to determine age, and to separate known races and stocks of steelhead trout (Salmo
gairdneri). Otoliths were the first calcified structures observed in X-ray photographs of steelhead embryos, and a continuous record of events through life was interpreted from these structures. A direct
relationship...
Dispersal is integral to our understanding of the life history and population biology of many vertebrates, but difficulties in detecting long distance movements have complicated its study. Moreover, studies of factors affecting dispersal are often unable to determine the relative contributions of variables such as nesting success, mate fidelity, and...
A study of the life history, population dynamics, and ecological relationships of the Columbian white-tailed deer (Odocoileus virginiarius leucurus) was conducted on the
Washington mainland, Columbian White-tailed Deer National Wildlife Refuge during 1972-1973 to provide information for management of this endangered subspecies. A total of 18,077 observations of deer recorded...
The minnow genus Siphateles is distributed throughout the Great Basin and adjacent drainages of western North America. Three species are currently recognized in the genus: S. alvordensis, Alvord chub, S. boraxobius, Borax Lake chub, and S. bicolor, the tui chub. S. bicolor has long been recognized as a widespread species...
A population of Nuttall's cottontails (Sylvilagus nuttallii) in Deschutes County, Oregon, decreased fromm 166 individuals in August 1978 to 76 individuals in August 1979. Survival rates of four annual litter groups in 1978 were 0.74, 0.35, 0.72, and 0.93; survival rates for the same litter groups, respectively, in 1979 were...
We assessed use and selection of cover by coastal cutthroat trout (Oncorhynchus clarkii
clarkii) in six headwater streams in three watersheds in western Oregon, USA during the summer low flow period from 1 August and September 30, 2007. We tagged 1037 coastal cutthroat trout (>100 mm) with passive integrated transponder...
The effects of potential parental egg production and
environmental factors on year-class strength (YCS) of petrale sole
(Eopsetta jordani) were investigated in two areas off Oregon and
Washington (Pacific States Marine Fisheries Commission areas 2B: 42°
50'N - 44°18'N, and 3A: 45° 46'N - 47°20'N). Indices of YCS based on...
This investigation demonstrates the feasibility of a
polyculture system using effluent water from land-based
salmon culture systems to feed juvenile Manila clams, Tapes
japonica (Deshyes), and an evaluation of an artificial diet
for feeding juvenile clams. An economic analysis of the
polyculture system was compared to cultures of a single...
This study evaluates the functional organization of stream fish assemblages in response to streamflow factors and biotic interactions across a range of spatial scale. The study area for this project includes 109 stream reaches located on tributaries to the upper Missouri River in the northern Great Plains. Fish distribution data...
Partial migration is a common migratory behavior where some individuals in a population migrate and others do not. Patterns of partial migration can vary dramatically, especially for species that inhabit a wide range of environments. I described and predicted spatial variation in marine migration (anadromy) of female Oncorhynchus mykiss (steelhead...
Zebrafish, Danio rerio, are widely used as vertebrate research organisms yet little is know about their responses to husbandry stressors. This dissertation examined the whole-body cortisol responses of zebrafish to husbandry stress. Additionally, the effects of stress on the susceptibility to mycobacteriosis and microsporidiosis (Pseudoloma neurophilia) were determined including effects...
Studies of avian movement ecology afford essential insights regarding species' life histories, population dynamics, habitat and resource requirements, and other ecological relationships. While it is widely recognized that events in different stages of the annual cycle have important implications for processes in avian ecology, evolution, and conservation, challenges associated with...
Shorebirds display great variation in mating systems and breed in dynamic environments that are increasingly subject to human threats worldwide. In order to adequately assess productivity and demography of shorebird populations, it is important to understand factors that influence patterns of parental care and reproductive success. The Black Oystercatcher (Haematopus...
The decline of many Pacific salmon stocks has stimulated interest in the early life history and habitat requirements of juvenile salmon. Although estuarine habitat associations of juvenile salmon have been investigated in many coastal areas of the eastern Pacific Ocean, until recently, little was known about juvenile salmonid ecology within...
Determining age in crustaceans is inherently imprecise because they molt
periodically and do not retain hard structures throughout their lifespan. Morphological
measurements, such as carapace length, are often used to estimate age because
methods for direct ageing do not exist. However, variability in individual growth rate
and molt frequency can...
The Pacific Northwest has a relatively low diversity of primary freshwater fishes with most of the endemism and diversity in the Columbia River and Klamath River. However, the Oregon Coastal Subprovince defined as the coastal rivers from Miami River in the north to Sixes River in the south, has a...