Population genetic techniques are now preeminent in differentiating wild populations. Natural resource managers rely on them in their efforts to restore viable populations of fish and wildlife. Overfishing adversely impacted Yelloweye Rockfish (Sebastes ruberrimus) on the U.S. West Coast in the late 20th century. Management actions included shutting down the...
Riparian forests provide a myriad of ecosystem functions for adjacent streams and rivers, and due to these linkages, changes in riparian forest conditions can have direct implications for stream ecosystems. Resource managers in the coast redwood forests (Sequoia sempervirens) of northern California (USA) are actively thinning second-growth stands to accelerate...
The natural environment provides important services and benefits to peoples’ health and lives. Conversely, environmental disservices can have negative impacts on humans such as through pollution, chemical toxins, and climate change. The combination of environmental services and disservices encompass how human health and wellbeing, and the environment are connected. As...
Non-toxic species of desiccated blue-green algae, or cyanobacteria, may offer potential for use as a fertilizer on irrigated crops. Here, the non-toxic cyanobacteria species Aphanizomenon flos-aquae (AFA), collected from Upper Klamath Lake, Oregon, was evaluated for use as a biofertilizer in a controlled experiment on Swiss chard “Bright Lights” (Beta...
Carnivores have disproportionate effects in ecological systems but understanding their exact influences on ecosystems is a matter of great complexity and debate. Predators directly impact prey by killing them, and indirectly by modifying their behavior in response to predation risk. Yet how species interact, both among members of a carnivore...
RNAseq data among copepods (Calanus pacificus) were sampled and analyzed in relation to oceanographic and climatic conditions to determine if new information derived from such an approach might assist applications that use copepods as ecosystem indicators to predict fishery yields. These samples were taken as part of long-term studies conducted...
Climate change is a global phenomenon, but natural selection occurs within landscapes. A central tenet of landscape ecology is that mobile species depend on complementary habitats, which are insufficient in isolation, but combine to support animals through the full annual cycle. For coldwater fishes, it is widely assumed that maximum...
Microplastics (<5mm diameter) are present in a considerable number of marine and aquatic species. Understanding which species, the global spatial distribution, and what quantities of microplastics are present is extremely important for understanding the potential impacts they could have on recreationally important organisms and for the assessment of risk. We...
The relationship between population characteristics and population productivity is fundamental to sustainable fisheries management, but predicting productivity remains a challenging task. Proposed mechanisms driving the variability in productivity at a given population size have included environmental and demographic factors related to the age structure of the population, but the broad-scale...
Aquatic and riparian systems in the western United States have been highly modified by anthropogenic impacts since Euro-American settlement. Ecological restoration is a practice that has been widely conducted around the world to mitigate the degradation of these systems. The majority of stream restoration efforts have focused on improving in-stream...
Many economically important Pacific salmon fisheries along the west coast of North America are mixed-stock, recreational systems, in which managers strive to account for interactions between fish, anglers, and management policy while balancing fishery access against conservation of vulnerable stocks. Specific challenges facing fisheries managers include limited control over angling...
Land-use change, particularly in the form of the conversion of primary forest to forest-matrix systems, alters species communities and species interactions. Describing these often complex and nuanced species responses is one of the great challenges in ecology. Another complementary challenge is finding and using the most efficient means for collecting...
Isotope and stomach content data from piscivorous reservoir fishes collected from Hills Creek (isotopes; 43°40′16″N 122°25′33″W) and Lookout Point (isotopes and stomach contents; 43°53′48″N 122°43′34″W) reservoirs located on the Middle Fork Willamette River, Oregon. Additional details can be found in the related publication.
Isotope sampling was conducted under OSU Institutional...
An inextricable link exists between dams and human development in the Pacific Northwest, but they can fragment rivers and reduce genetic connectivity for freshwater and anadromous fishes. Since the early-twentieth century, a series of hydropower and irrigation dams on the mainstem Klamath River, California, has fragmented migratory corridors and eliminated...
Mangrove forests store more organic carbon across ecosystem carbon pools than most other coastal and forested ecosystems, and are subject to high global rates of deforestation. For these reasons, they are recognized as prime candidates for inclusion in climate change mitigation strategies. However, the ecological drivers of regional and micro-scale...
A substantial fraction of estuarine tidal wetlands have been lost to development or other human uses in the Pacific Northwest since the 1800s. Wetland restoration, typically through tidal re-connection, can restore normal tidal hydrology to these areas and improve estuarine capacity to support ecosystem functions and services. Restoration may initiate...
The anadromous Pacific Lamprey (Entosphenus tridentatus) is a biologically and culturally important species native to the North Pacific Ocean and its adjacent freshwater tributaries. Pacific Lamprey have experienced declines in abundance and distribution throughout their native range, highlighting a need for further research on the species to better inform conservation...
The northern spotted owl (Strix occidentalis caurina; spotted owl) is of conservation concern and endemic to mature forests of the Pacific Northwest. Adult survival has a strong effect on population growth rate, but juvenile survival and recruitment are also important components of population change. Despite the importance of this life...
The life history traits of polygamous, non-territorial shorebirds like the Red Phalarope (Phalaropus fulicarius) can make it challenging to assess their population status. There are two general approaches to statistical inference used to understand shorebird (Order: Charadriiformes) population change: design-based inference, which implements an a-priori sampling scheme with known selection...
Passive acoustic monitoring is a valuable tool for observing the status of marine environments. Comparisons of underwater soundscapes over temporal and spatial scales can provide data to inform marine conservation efforts, including protection of threatened and endangered species. This dissertation utilizes passive acoustic data collected via a broadly spaced array...
Understanding prey quality and prey selection by predators is critical for management efforts aimed at identification and protection of essential habitats and prey. Marine predators must make daily foraging choices in a heterogenous and dynamic environment in order to meet the high energetic demands of migration, reproduction and foraging. With...
Livestock grazing occurs worldwide, spanning over 25% of land globally. Effective conservation of biodiversity relies upon understanding the interactions of agricultural management practices and increasingly variable weather associated with climate change. I evaluated grazing, weather and predator-prey interactions within a grazing experiment in the sagebrush ecosystem of southeastern Oregon. I...
Pacific salmon are culturally and economically important species to Southeast Alaska, where there is a history of large wild runs and supplemental production from hatchery programs. Salmon management in Alaska is divided amongst various governmental agencies. Non-governmental organizations also play a pivotal role in salmon management. To fulfill the requirements...
Animal weapons are thought to have evolved to compete for reproductive opportunities within a species. Across the diverse weapon-bearing taxa, several evolutionary trends have emerged: (1) increasing complexity and relative size across ontogeny, (2) sexual dimorphism, and (3) higher levels of random deviations from symmetry (i.e., fluctuating asymmetry) than non-weaponized...
Spatial capture-recapture (SCR) is employed for estimating abundance and density of species, particularly those that are cryptic or solitary, and evaluating how population density varies with habitat. However, it is uncertain whether estimates are biased when applied to species that aggregate, such as elk (Cervus canadensis). Wildlife managers in the...
The goal of this project was to estimate the total annual cost of salmon recovery efforts throughout the Columbia River Basin from all stakeholders, including direct and indirect costs. How much is spent on salmon recovery efforts each year in the Columbia River Basin? Depending on who you ask, you...
Pacific salmon (Oncorhynchus spp.) rearing in lakes and reservoirs have been known to become heavily infected with an ectoparasitic copepod (Salmincola californiensis). Little is known about the factors that affect the parasite infection prevalence and intensity. However, previous research suggests that the parasite may negatively affect the fitness and survival...
Pacific lamprey is an important cultural and ecological species to freshwater ecosystems of the Pacific Northwest. Lamprey often rear in low gradient portions of watersheds that have high exposure to climate warming, yet very little is known about their thermal physiology in comparison with other anadromous fishes such as Pacific...
Freshwater rearing is a critical period in the life cycle of anadromous salmonids, known to produce carry-over effects mediating long-term growth and survival. Freshwater growth is primarily determined by food availability and temperature. While many species of salmon rear in freshwater for a full year or longer, most trophic ecology...
Fisheries management that is based on quantitative assessment has commonly relied on estimating the unfished biomass of a fished stock to compare current and historical population size. Developing predictive models for this requires many years of catch and abundance data. Smaller, new, or mainly recreational fisheries may not have the...
The social sciences are increasingly used in conservation to describe interactions and relationships between humans, wildlife, and ecosystems. Scientists and policy-makers have concluded that promoting human tolerance for wildlife is critical to the success of conservation efforts. Yet, the concept of tolerance is relatively new in the context of human-wildlife...
Fundamental objectives in the field of conservation biology involve understanding the processes that influence small and declining populations and applying that knowledge to develop appropriate monitoring strategies and targeted management and conservation actions. Critical first steps in determining the relative role of factors that drive population declines involves estimation of...
Pollination is an essential ecosystem service that sustains functioning ecosystems and aids in food production. In response to recent, widespread declines of managed and native bee populations, many land managers have shown interest in developing conservation and restoration plans for enhancing native bee habitat. However, there is a lack of...
Shallow lakes exist in either a clear or turbid state, with the clear state characterized by an abundance of aquatic macrophytes, diverse aquatic biota, low water column nutrients and phytoplankton biomass, whereas the turbid state is characterized by the opposite. These two distinct states are maintained by reinforcing (positive) feedback...
The western United States has experienced large-scale degradation due to land use and land cover changes, invasion of annual grasses, and expansion of woody plants into grass and shrublands and the resultant altered fire regimes. These landscape-scale changes have coincided with declining mule deer (Odocoileus hemionus) populations, making habitat loss...
Advances in mobile autonomous vehicles for oceanographic sensing provide new opportunities for passive acoustic monitoring of marine mammals. Acoustically equipped mobile autonomous platforms, including gliders, deep-water profiling floats, and drifting surface buoys can survey for a variety of marine mammal species over intermediate spatiotemporal scales. Additionally, such mobile platforms may...
A deep neural network was developed and trained to identify the sounds of pomacentrids (damselfishes) in the National Park of American Samoa. Four years of continuous, passive acoustic data were recorded by a single stationary hydrophone. Deep neural networks enable the full utilization of such large datasets by automating laborious...
In the western United States, bighorn sheep (Ovis canadensis) have suffered major die-offs in every state since the mid-1800s, and disease from domestic sheep (Ovis aries) has been a primary factor in these events. Beginning in the early 1900s, poly-factorial, poly-microbial pneumonia was identified as a major disease affecting bighorn...
The ultimate goals of this project are to 1) provide farmers with data-based advice on maintenance and enhancement of habitat for native wildlife based on what species are using the remnant/unfarmed patches on producers farms and to 2) provide background knowledge and data to enable development of a larger project...
Grape growers seeking to protect their grapes from bird depredations have no economic guidelines for selecting one or more of several control alternatives. Many growers are not aware of the cost of applying the various control techniques, nor do they know how effective these techniques are in preventing damage to...
Anthropogenic activities have posed many threats to the oceans and marine life. Understanding how individuals are affected and physiologically respond to these threats is crucial and allows for management and conservation applications. I evaluated the overall health condition of a subpopulation of gray whales (Eschrichtius robustus) along the Oregon coast,...
As regional climates warm in the Pacific Northwest, USA, flow minima and temperature maxima may become more synchronous in headwater streams over time. The dual stresses from lower flows and warmer temperatures will be energetically costly for cold-water species such as Coastal Cutthroat Trout and Coastal Giant Salamander. Individual fates...
Animal pollination is critical to plant reproduction in agricultural and wildland ecosystems. Much of the production of seeds and fruits in natural areas, which underlie many food webs, depends on pollination services by insects. The taxon responsible for delivering the bulk of these services in most temperate systems is bees....
The greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) is a ground nesting gallinaceous bird that requires large contiguous patches of sagebrush. Sage-grouse populations have declined, especially in the Great Basin where changes in wildfire regimes and the invasion of annual grasses have contributed to habitat loss and fragmentation. During the last...
The role that anthropogenic and natural habitats in estuaries play in long-term population trends for Oregon’s nearshore marine fishes is poorly understood, in part due to limited temporal sampling. One important nearshore marine group is northeastern Pacific rockfishes (Sebastes spp.), which are highly diverse, with around 96 documented species, and...
The 1989 Exxon Valdez oil spill (EVOS) in Prince William Sound, Alaska provided impetus for a great deal of research into the ecosystems of the Northern Gulf of Alaska. Buried within the multitude of resulting impacts, which included hundreds of thousands of oiled seabirds and dramatic ecosystem shifts in the...
Human alteration of natural landscapes leads to biodiversity loss, often from a combination of area effects and fragmentation effects. Smaller habitat patches support fewer species than large ones and incur additional consequences from isolation. Efforts to preempt biodiversity loss from insular habitat fragments are complicated by individualistic species responses and...
The National Park Service has a dual mission of providing public access to exceptional natural resources, but in a manner such that these resources are left “unimpaired for the enjoyment of future generations.” Human activities in parks undoubtedly affect wildlife, but the degree to which such activities cause impairment is...
Somatic growth variation manifests from the cumulative effects of a suite of biological, ecological, and environmental processes and can have profound effects on individual fitness and species population dynamics. As ectotherms whose growth dynamics are greatly influenced by environmental factors, sea turtles display considerable variation in somatic growth within and...
The structure of food webs and how they relate to community stability has been an important debate in ecology. Specifically, predictability of web shape and how it influenced by surrounding landscapes is one of the main goals of such discussions. Headwater streams provide a study template that is of interest...
The detection of white-nose syndrome (WNS) in King County, WA in 2016 prompted the National Park Service to mobilize region-wide bat monitoring and disease surveillance. One of the goals of the Pacific West Region WNS response plan was to implement acoustic monitoring to determine the distribution of bat species and...
Policy development and decision-making play a critical role in natural resource management in the Pacific Northwest. To realise my internship requirements for the Professional Science Masters in Fisheries and Wildlife Administration, I completed internships with: the Oregon Department of Fish and Wildlife (ODFW), Portland State University – National Policy Process...
The Columbia River Basin historically supported abundant populations of Pacific salmon (Oncorhynchus spp.) but, largely due to anthropogenic influence, many populations are now listed as threatened or endangered under the U.S. Endangered Species Act. Habitat restoration efforts have been a critical component of salmon recovery plans. However, although the importance...
The California Current Ecosystem (CCE) is a dynamic marine ecosystem from which many socioeconomically important fisheries species are harvested. In this thesis, a genotyping-by-sequencing (GBS) approach was used to examine genomic variation in an early life stage of the Dungeness crab (Cancer magister), which constitutes the most valuable single-species commercial...
Projected intensification of drought as a result of climate change may reduce the capacity of streams to rear fish, exacerbating the challenge of recovering ESA-listed salmon populations. Without management intervention, some stocks will likely go extinct as stream drying and fragmentation reduce juvenile survival to unsustainable levels. To offset drought-related...
Nearly all birds communicate through sound, and there has been much study of avian populations and communities using song and other vocalizations. Owls are no exception as they defend territories, advertise for mates, and defend against threats using various vocalizations. However, due to their generally nocturnal habits, some owl species...
Chinook salmon are widely distributed across the globe with native stocks in the North Pacific Ocean and self-sustained populations introduced to regions in the Northern and Southern Hemispheres. Pacific salmon are economically and ecologically important to the Pacific Northwest, USA, yet several wild populations are federally listed as endangered or...
Anadromous salmonid populations in the Pacific Northwest have declined over the past 150 years. In 1999, wild spring Chinook salmon (Oncorhynchus tshawytscha) were federally listed as threatened within the Willamette Basin, OR. Currently, practices to restore wild populations in the upper Willamette Basin involve trapping wild adults at the base...
Investigation into how animals move within the landscape is important for both understanding of ecological processes and conservation management. Animal movement is important in shaping life history transitions, demographics, individual fitness, and species distributions. However, as landscapes become increasingly affected by human activities, movement becomes important as species navigate landscapes...
The goal of my dissertation was to explore how scale influences stream restoration prioritization strategies for an anadromous species and identify influential uncertainties that exist at different scales. My objectives were to (1) produce a comprehensive review of the Chinook salmon management challenges in California’s Central Valley and identify the...
This paper is an assignment for my Ichthyology class at Oregon State University. I was tasked with creating a new fish species that is scientifically possible and telling a fictional story of its discovery.
After a 40-year absence from Oregon’s landscape, expanding gray wolf (Canis lupus) populations are reestablishing elements of interspecific competition with sympatric large carnivores, like cougars (Puma concolor). This presents new challenges for management of large carnivores and their ungulate prey populations (e.g., elk, Cervus canadensis nelsoni; mule deer, Odocoileus hemionus)...
One fundamental concern in conservation biology is species abundance. For many taxa, however, these data are costly to obtain via direct observation and thus limited in geographic or temporal scope. Very high-resolution satellite imagery provides a means to address these limitations and provide remotely-sensed counts of large, colonial species. We...
Humans have drastically altered the physical habitat and food web structure of stream ecosystems. Two major impacts humans have had on Pacific Northwest streams are modification of streamside forests (as a result of agriculture, land development, and timber harvest), and declines in the return of wild anadromous salmon to headwater...
This document reports on findings, conclusions and recommendations derived from scientific literature and knowledge regarding the effectiveness of tide gate removal or upgrade in improving conditions for Oregon’s native migratory fish species, particularly salmonids, and other plant and animal species that utilize estuarine ecosystems. The project was commissioned by the...
The Pacific Oyster (Crassostrea gigas) is one of the most economically and ecologically significant shellfish species worldwide. In the Pacific Northwest United States (PNW), the sustainability oyster stocks is increasingly threatened by ocean acidification (OA), which has had significant negative effects on the aquaculture industry in this region over the...
Large dams and their respective reservoirs can provide renewable energy and water security, but also profoundly alter riverine ecosystems. In the Pacific Northwest, dams and reservoirs cause discontinuities in river networks that have been particularly problematic for anadromous fishes. As barriers to the upstream and downstream migration of anadromous fishes,...
Globally, the number of threatened species is increasing and conserving them is a high priority to the scientific community. Assessing the status of these protected species is challenging due to missing, contested, and or contradictory data streams. Integrated models (IMs) provide a statistical framework for combining disparate data sources to...
In Southeast Alaska, Eulachon (Thaleichthys pacificus) are a culturally and biologically important anadromous fish. Eulachon populations have significantly declined in the southern part of their range, and in 2010 eulachon in northern California, Oregon, and Washington were listed as a threatened species under the Endangered Species Act. In the same...
A fundamental objective of ecology and population biology is to identify factors that drive population dynamics and determine the population-level consequences of their interaction with the environment. Studies of reproductive performance can illuminate population dynamic processes, including the links between organismal biology, the environment, and life history theory. A central...
The expansion of native, woody plants is a global phenomenon with characteristics and effects that are often indistinguishable from exotic invasions. These expansions have largely been driven by altered fire regimes and favorable climatic conditions. In the Great Basin of western North America, expansion of conifers such as western juniper...
The social sciences have the capacity to contribute to natural resource management through investigations of human dynamics associated with the environment. Sense of place (SOP), the formed relationships between an individual and the environment, has been considered a fundamental aspect of human well-being and can contribute to more holistic understanding...
Vibrio coralliilyticus (Vcor) is a bacterial pathogen that is well adapted to shellfish hatcheries and is very pathogenic to the larvae of the Pacific oyster Crassostrea gigas. Vcor has been associated with several large scale larval mortality events in the Pacific Northwest that interrupt the supply of seed oysters available...
Models of a species’ distribution and models of a species’ spatially explicit density are valuable tools for conservation. They allow researchers to estimate changes in distributions, densities, and populations, based on changing environmental conditions. To trust such estimates, however, the quality of models is exceedingly important. Model performance can be...
This study used a factorial mesocosm design to quantify American bullfrog (Lithobates castebeianus) eDNA to assess the relationship between body size, density, and eDNA shedding rates.
The mission of federal fish hatcheries has evolved over decades under budgetary changes and new conservation regulations and policies. I evaluated the US Fish and Wildlife Service Abernathy Fisheries Technology Center, which has experienced this evolution from a production fish hatchery with research programs to a non-production, cutting edge, basic...
Declines in wild salmonid (Oncorhynchus spp.) populations in the Columbia River basin have resulted in managers identifying that avian predation on juvenile salmonids is an important limiting factor for salmonid recovery. Caspian Terns (Hydroprogne caspia), particularly those nesting in the Columbia River estuary, were identified as key avian predators that...
Small-scale fisheries (SSF) around the world face many challenges. They are a highly dynamic, important sector for coastal communities in developing nations, playing a critical role in poverty alleviation and food security. SSFs generally have few resources to ensure their long-term sustainability. They are often fished and managed locally and...
The management of small-scale fisheries (SSF) around the world is facing increasing demands for reformation given ecological, social, and economic vulnerabilities. The governance of SSF is particularly important to foster the sustainability of these systems given that it combines regulatory instruments, interactive participation of diverse stakeholders, and the guiding values...
Pacific harbor seals (Phoca vitulina richardii) are one of Oregon’s most common coastal predators, numbering between 10,000 and 12,000 individuals (Brown et al. 2005b). They consume more than 149 species or types of marine prey within the Pacific Northwest, which include a large variety of commercially important fisheries species. Despite...
2018 Library Undergraduate Research Awards nomination materials, reflective learning essay, and research paper.
In this study, pocket gopher and gray-tailed vole holes and hills were counted within four distinct habitats using quadrats and a gridding method over a period of five field days. The study was conducted to determine which...
Migration and spawning phenology of Pacific Salmon is linked to the hydroregime, and thought to be triggered by increases in river discharge and decreases in water temperature. However, little data exists that describes direct fine-scale linkages between the hydroregime and spawning in Coho Salmon. This study evaluated the spatial and...
Year-round habitat use of marine predators provides knowledge of important marine areas throughout different life stages. Large-scale, environmental variability, both in space and time, causes changes in the behavior and distribution of marine predators that are important to quantify for conservation. In the Northern California Current System (NCCS), common murres...
Declines in populations of anadromous salmonids (Oncorhynchus spp.) in the Columbia River drainage basin have resulted in extensive programs to annually release large numbers of hatchery-raised juvenile salmonids in an effort to support salmonid restoration. The Pacific Flyway population of Caspian terns (Hydroprogne caspia) has grown from around 3,500 nesting...
Fishers (Pekania pennanti) are medium sized mustelids endemic to North America. Two fisher populations persist in Oregon: an indigenous population in southwestern Oregon, and a reintroduced population in the southern Cascade Mountains. Despite candidacy for listing under the Endangered Species Act, current information on fisher populations in Oregon is scarce....
For over 100 years, National Parks have existed to preserve America’s natural and cultural heritage for current and future generations. As environmental pressures on wildlife and habitats have increased in recent decades, National Park lands have become important protected areas for many threatened and endangered species. Conservation and management of...
Species conservation depends on robust population assessment. Data on population abundance, distribution, and connectivity are critical for effective management, especially as baseline information for newly documented populations. I describe a pygmy blue whale (Balaenoptera musculus brevicauda) population in New Zealand waters with year-round presence that overlaps with industrial activities. This...
Up to 99.9% of native North American grasslands have been degraded since European settlement, primarily due to agricultural conversion. Today, grasslands are a top priority for restoration as they provide essential habitat for many rare and endangered species; however, the majority of studies in grasslands have focused on vegetation or...
Biodiversity loss in highly diverse systems such as coral reefs has been linked to significant declines in the ecosystem functions and services provided by marine species. Ecological functioning of coral reefs and the resistance of coral reef fish communities to disturbance depend on the functional traits of species that promotes...
Characiform fishes form one of the most diverse freshwater fish clades in the world. Comprising more than 2000 species and distributed primarily in South America and Africa, characiforms vary dramatically in their ecomorphology. However, the evolutionary processes responsible for the immense ecomorphological diversity remains unknown. Recently, a study postulated that...
Humpback whales (Megaptera novaeangliae) are a widely distributed baleen whale species, well known for their diverse acoustic behavior. On high-latitude foraging grounds, humpback whales produce a suite of non-song vocalizations (“calls”) in concert with foraging and social behavior. In this dissertation I investigated the role of calls in the acoustic...
Background. Ampelisca eschrichtii Krøyer, 1842 of the Sakhalin Shelf of the Okhotsk Sea, Far Eastern Russia, comprise the highest known biomass concentration of any amphipod population in the world and are a critically important prey source for western gray whales. Growth and reproduction in this population has not been apparent...
Informed conservation of small mammals, ecosystems, and predators requires a detailed understanding of how small mammals species and communities vary in both space and time, as well as the relative cyclicity and synchrony of this variation. This variation can be especially informative to land managers interested in manipulating the abundance...
Cross-seasonal effects, where conditions in one season can have consequences in a following season, can have population-level implications for migratory species. To assess the presence of cross-seasonal effects on a migratory dabbling duck population, we examined the relative importance of habitat conditions in multiple seasons on the subsequent productivity of...
In this study, we used a combination of conventional statistical analyses and mechanistic bioenergetics models to understand the potential effects of environmental variability on growth of stream-living fishes in four headwater streams subject to upstream forest harvest. We focused on two common fish consumers in headwater streams in the Pacific...
Collaborative decision-making is often promoted as a means to achieve socially acceptable and enduring solutions to natural resource management issues, and one that holds promise for resolving “wicked” problems. However, success rates for implementation of collaborative recommendations are unknown. This paper explores challenges to collaborative salmon fishery management in Prince...
California bighorn sheep (Ovis canadensis californiana) were studied on Hart Mountain, Oregon, during the summer and fall of 1976, and the spring of 1977. The population consisted of a minimum of 196 sheep in June, 1977. The high number of lambs observed and high lamb:ewe ratios throughout both years of...
Commercial whaling during the 20th century drastically reduced many populations of great whales in the Southern Hemisphere. The Antarctic blue whale, for example, is estimated to have been reduced to less than 0.1% of its original abundance based on catch records and population dynamic models. Despite this population bottleneck, several...
From July 1985 to April 1987 the pelagic zooplankton community of Crater Lake, Oregon was studied to determine taxonomic structure, absolute and relative densities, and spatial and temporal distributional patterns. Samples were collected using vertically-towed zooplankton nets. The community structure consisted of two cladoceran and nine rotifer species, which were...