Resident bull trout (Salvelinus confluentus) may be particularly vulnerable to human related disturbance, however very few studies have focused on resident bull trout populations. The abundance of bull trout is one measure of the strength and potential for persistence of a population. Habitat characteristics may influence resident bull trout abundance...
The Tillamook and Kilchis subbasins of the Tillamook Bay watershed (Oregon Coast Range) have differences in geology and land use history and, therefore, varied environmental conditions that could affect fish assemblages. Fifty-two randomly selected wadeable stream reaches in these two subbasins were surveyed for stream habitat and fish assemblage composition...
Redband trout (Oncorhynchus mykiss gairdneri) are found over a wide range of environmental conditions and are known for their variability in life history traits among watersheds or even within streams. Life history traits and population structure of these trout can be influenced by a variety of anthropogenic changes including habitat...
In the summers of 1998 and 1999, aquatic invertebrate and plant communities were sampled from nineteen springs in the Warner Basin of southeastern Oregon. Across the landscape, these springs exhibited a broad range in water temperature (5-24°C), pH, conductivity, elevation, and gradient. Within a particular spring, water temperature and chemistry...
One of the greatest threats to native bull trout Salvelinus confluentus populations is the presence of non-native brook trout S. fontinalis. This study, conducted in two second-order Eastern Oregon streams, investigates the effect of brook trout on the feeding behavior arid diet of bull trout. Feeding behavior, microhabitat use, and...
Fishery dependent data--length distributions, sex ratios, maturity schedules, and species composition of landed catches--are necessary for stock assessments. These data are currently collected by state port biologists using a sampling design that randomly selects samples from a small percentage of a very large target population. Sampling programs may need to...
The development of assays for stress in marine fishes is vital for studying the impacts of bycatch in fisheries and for determining the health of fish being cultured or used in research. This research developed behavioral and physiological assays for stress in juvenile sablefish, Anoplopoma fimbria, a species that comprises...
Stress, including extreme or rapidly changing temperatures, are known to have deleterious effects on fish health and physiology. This thesis examines the combined effects of elevated acclimation temperature and acute handling stress on the number of antibody producing cells, plasma lysozyme concentrations, and the number of pronephric leukocytes in juvenile...
Pacific lampreys (Lampetra tridentata) have declined in abundance in the Columbia River Basin. Although, the reasons for the decline are unclear, we suggest that development of hydroelectric dams and habitat alterations in tributaries as the main causes. The available knowledge of life history of Pacific lampreys and status from dam...
Response of aquatic vertebrates to increased pool habitat complexity due to abundance of large wood was evaluated experimentally in three streams in the Cascade Mountains of Oregon. No difference in aquatic vertebrate density was detected among treatments, though there was a trend of increasing aquatic vertebrate density with increasing large...
Effects of spray-dried algae, Schizochytrium sp. and Haematococcus pluvialis, on growth and survival of Manila clam, Tapes philippinarum, spat were determined. Results of the present study showed that these two different spray-dried diets supported clam growth when added as supplements to rations of a mixed diet of the live algae...
In the tropics, widespread deforestation and conversion of primary forests to agricultural and pasture lands has resulted in losses of composition, structure, and functions of forest landscapes. Deforestation in the tropics is typically preformed via slash-and-burn practices; the byproducts from combustion have been identified as the second-highest form of anthropogenically...
Since their range expansion into the Pacific Northwest, anecdotal evidence suggests that northern barred owls (Strix varia varia) may be displacing northern spotted owls (Strix occidentalis caurina). My objectives were to characterize barred owl distribution and population increase in Oregon, investigate spotted owl territory performance before and after barred owl...
I examined ecological relationships and mechanisms of coexistence for sympatric populations of Columbian white-tailed (Odocoileus virginianus leucurus) and black-tailed deer (Odocoileus hemionus columbianus) in Douglas County, Oregon, from September 1997 to August 1998. Horseback transects were used to describe spatial distributions, population overlap, and habitat use for both species. Behavioral...
The status of wild sheep in North America typifies the plight of many wildlife species in modern times: wild sheep have declined to 10-40% of their numbers during pristine times and on a global scale approximately 31% of Caprine are considered threatened or critical. As human populations and the number...
Avian movement behavior provides insight on patterns of regional and local fidelity, habitat and resource requirements, the scale at which individuals perceive the landscape, and the relative influence of the spatial array of resources. Shorebirds (suborder: Charadrii) are a diverse and mobile group of wetland associated species. Large numbers of...
Although widely studied in many portions of North America, little is known about the specific habitat requirements of mallard ducks (Anas platyrhynchos) during the breeding season in western Oregon. I radio-marked 72 female mallards in the Willamette Valley of Oregon in March-April 1995-96 to document wetland habitat selection during pre-nesting...
Seasonally, in 1998 and 1999, I examined spatial and temporal variation in fish assemblages of agricultural, forested, and acid mine drainage tributaries within the Wayne National Forest (WNF) in southern Ohio. Land use and natural disturbance explained patterns in stream fish assemblages. Creek chub and green sunfish were present in...
Environmental factors such as chemical contamination can have immunomodulatory effects on the immune response of fish and may be contributing to the decline in salmonid populations by augmenting disease susceptibility. Xenobiotics can interfere with the immune system at several levels of complexity, and different immune cells and processes have variable...