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...
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...
To best manage Eagle Creek National Fish Hatchery and minimize any negative impacts that the current hatchery program may be having on Endangered Species Act-listed salmonids in the Eagle Creek Basin, I determined if wild fish are being displaced from preferred habitats by hatchery salmonids Oncorhynchus spp. This thesis had...
The extent to which responses to stress are maladaptive or adaptive to the long-term survival of fish remains to be better understood. The aim of this study was to identify differentially expressed genes in the livers of rainbow trout, Oncorhynchus mykiss, responding to an experimental stressor. Gene expression responses were...
Estuaries provide juvenile salmonids with highly productive feeding grounds, refugia from tidal fluctuations and predators, and acclimation areas for smoltification. However, these dynamic, fluctuating salinity environments may also be physiologically stressful to growing juvenile fish. In order to evaluate the costs and benefits of estuarine marshes to juvenile Chinook salmon,...
In this thesis, we examined the effects of the exposures to anthropogenic pollutants on the fish, primarily juvenile chinook salmon, immune system using newly and recently developed immune assays. In addition, we developed a new assay for measuring immunocompetence of fish. In the first chapter, the Alamar Blue assay was...
Wild populations of fish are faced with a multitude of stressors, which may include human interaction, toxins, and disease. Benzo(a)pyrene (BaP), a known carcinogen and immunotoxin, has been reported in the stomach contents of juvenile chinook salmon, Oncorhynchus tshawytscha, in urban waterways. We investigated the impact of chronic dietary exposure...
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 present study investigated the neurocrine and neuroendocrine control of locomotor activity, habitat choice, social behavior, and migratory behavior in juvenile chinook salmon (Oncorhynchus tshawytscha). This was achieved by the manipulation of three neurotransmitter systems; serotonin (5-HT), dopamine (DA), y-amino-n-butyric acid (GABA) and the neuropeptide corticotropin-releasing hormone (CRH). Chemicals were...
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...