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 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...
Sex differentiation in fish is a labile process that allows sex inversion in several species. The inherent capacity of fish germ cells to differentiate into oocytes or spermatocytes constitutes a key factor allowing for functional sex inversion. This thesis set out to determine the mechanism involved in steroid-induced sex differentiation...
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...
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...
Processes of metamorphosis, settlement, and growth were examined in Pacific sanddab
using field studies and otolith microstructure. This flatfish transforms at large sizes, has a
gradual metamorphosis, and settles to a nursery on the middle continental shelf. Eye migration
takes 3 months and "metamorphosis proper" which begins after completion of...
Sex steroids, follicle stimulating hormone (FSH),
luteinizing hormone (LH) and gonadotropin releasing hormone
(GnRH) were measured in monosex and mixed sex populations of
rainbow trout during early development. Steroids declined
following fertilization, increased at hatch, then fell and
remained constant thereafter. Trends toward differences in
steroids between males and females...
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...
Spring chinook salmon, Oncorhynchus tshawytscha, in the Snake River Basin are listed as endangered under the Endangered Species Act. The typical life history of spring chinook salmon is semelparous. An experiment was performed to see if mature male spring chinook salmon parr could be reconditioned after hand-spawning and spawned in...
A series of experiments with Aeromonas salmonicida and infectious
hematopoietic necrosis virus (IHNV) were carried out to determine dynamics of the
spread of infection in chinook salmon (1.2-1.98g) and rainbow trout (1.2-3.1g). It was
found in experiments with A. salmonicida that fish infected by bath immersion became
infectious at 4...
Co-management is considered an alternative approach to fisheries management,
however, not all co-managed fisheries have been successful. Most studies discussing the
success and failure of co-management have emphasized economic and social attributes of
success and failure, such as fishery rights and institutional arrangements. The effect on
co-management of biological characteristics,...
The composition and distribution of fish assemblages was examined in a
floodplain lake system in the Amazon basin. Quantitative samples were
collected during the 1992-1993 flooding season at Marchantaria Island, Solimoes
River. A total of 25,819 specimens representing 8 orders, 30 families, 101
genera and 139 species of fish were...
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...
Marine ecosystems can be exposed to natural and anthropogenic disturbances that can lead to ecological failures. Marine reserves have been lately suggested to protect marine populations and communities that have been affected by habitat destruction and harvest. This research evaluates the potential role of two marine reserves established in Oregon...
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...
From 1998-2000, laboratory studies were conducted to examine factors that impact saltwater-entry behavior and saltwater preference (SWP) of juvenile chinook salmon, Oncorhynchus tshawytscha. These factors included bacterial kidney disease, stress and the presence of trout, O. mykiss. An additional study investigated the orientation of the startle response of chinook salmon...
Recent emphasis on linkages between essential fish habitat and fish stock productivity has raised concerns about the management of fishing activities such as trawling, which have the potential to impact fish habitat. Knowing specifically where and how intensively trawl effort has occurred over time provides ecologists with the necessary background...
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...
