Two studies on Catherine Creek and Meadow Creek of the Upper Grande Ronde
River basin, quantified several physical and biotic influences on woody riparian community
composition and structure. The Catherine Creek study examined the association of woody
riparian species with elevational and geomorphic gradients. The Meadow Creek study
examined the...
The work presented in this dissertation examines possible
modes of action for growth inhibition by anthropogenic endocrine
disrupting chemicals (EDCs) as well as endogenous hormones
associated with growth in fish. Using the sheepshead minnow (SHM)
(Cyprinodon variegatus) as a model, I developed methods to examine
perturbations in the endocrine axis...
The migrations upstream of pre-spawned adult steelhead (Oncorhynchus mykiss) and
downstream of post-spawned steelhead (referred to as "kelts") can geographically and
temporally overlap in the Snake River, leading to management challenges for populations
listed under the Endangered Species Act (ESA). This thesis describes the development and
application of a method...
Depleted species of rockfish (Sebastes spp.) from the Northeast Pacific experience high discard mortality due to "barotrauma," induced from the rapid change in pressure during capture. Research suggests rockfish have the potential to survive barotrauma if immediately recompressed, but the potential for long-term recovery is unknown. In this project, we...
Over the last decade, the Oregon Department of Fish and Wildlife (ODFW) has documented a precipitous decline in the Crooked River redband trout (Oncorhynchus mykiss) population, prompting this study to address potential factors contributing to the decline. There are two main goals to this project: (1) identify potential factors contributing...
A number of steelhead (Oncorhynchus mykiss) populations are at risk throughout Oregon, including five populations that are federally listed as threatened or endangered. However, little is known about behavior and survival of these fish as they transition from freshwater to seawater. We investigated whether estuarine survival varies on a temporal...
The quality and availability of forage fishes and invertebrates can affect the behavior and productivity of predators that rely on these resources. This study measures the proximate composition of forage fishes and invertebrates from the southeastern Bering Sea to estimate prey energy density (quality) using a method that is ecologically...
Bycatch, or the incidental capture of non-target species, has been implicated as one of the main factors leading to population declines of many large marine vertebrates, including sea turtles. To effectively manage and conserve these long-lived species, their marine distribution, high use areas, foraging habitats, and regions of highest likelihood...
Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific lamprey enter freshwater and reside for ~ 1 year before spawning. This long exposure to the freshwater environment may affect...
Pacific lamprey (Entosphenus tridentatus) are experiencing population declines throughout their range. Xenobiotics could be an important risk factor for lamprey populations. Our goal was to establish if common herbicides, as used in forest management, could affect reproductive fitness. We determined that atrazine was a likely compound of greatest concern to...