Species associations of fifteen major commercial groundfish species in the
northeastern Pacific ocean and their spatial and temporal characteristics were studied
using Oregon bottom trawl logbook data, 1987 to 1993. Screening procedures were used
to remove questionable data from the original logbook files, which resulted in the
exclusion of information...
The endemic cyprinids of Lake Lanao, Philippines have been described as a species flock and are thought to be an example of explosive evolution. However, based on historical surveys, 16 of the 18 cyprinid species endemic to Lake Lanao are now believed to be extinct. Furthermore, non-native species have been...
Salmonid run sizes are strongly affected by their early marine stage. Fully understanding the life history of salmonids means understanding how they interact with their marine environment and with other fishes. Changes in the biological and physical environment off the Columbia River region affects the distribution and abundance of predatory...
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 effects of harvesting Pacific hake (Merluccius productus)
were examined with a multi-species numerical model composed of
seven logistic growth equations coupled by a food web. The
food web was composed of: California sea lions (Zalophus
californianus), hake, sablefish (Anaplopoma fimbria), spiny
dogfish (Squalus acanthias), a generic rockfish species
(Sebastes...
The usefulness of preplant nitrogen (N) in establishing
alfalfa in colder production areas has not been
well characterized. This study was conducted to determine
the effect of preplant N and soil temperature on
yield, percent N derived from biological nitrogen fixation
(PBNF), and shoot N concentration in alfalfa (Medicago
sativa...
China’s global influence in the realm of science and technology (S&T) has increased dramatically in recent times. China and the United States are now each other’s main partner in scientific collaboration. As a major research university, OSU is one of the institutions with a large stake in this international collaboration....
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...
:
_____________________________________________________________________
Carl B. Schreck
Steelhead (Oncorhynchus mykiss) are at risk throughout Oregon including five
Stock assessments use statistical models and empirical data to re-create the population dynamics of a stock in order to provide estimates of biomass and fishing mortality rates to inform fisheries management. Fish stocks are not uniformly distributed across spatial regions, but stock assessments typically ignore stock spatial structure, for the...
:
_______________________________________________________________________________
DavidB. Sampson
Stock assessments use statistical models and empirical data to re-create
Statistical modeling has evolved around building increasingly more complex models, even though it is common knowledge among statisticians that an optimal model size usually exists for any given data set. Having overly complex models leads to imprecise parameter estimates and tends to increase the subjective role of the modeler, which...
Twenty-three bottom-trawl fish assemblages were identified from the relative biomass of
33 dominant species that occurred in the National Marine Fisheries Services' triennial
trawl surveys over the continental shelf and upper slope off California, Oregon, and
Washington from 1977 to 1992. The assemblages accounted for about 70% of the total...
Stock assessments for many U.S. Pacific coast groundfish stocks are developed using the catch-at-age method known as Stock Synthesis. In this work a simulation package was developed and used to evaluate the sensitivity of the Stock Synthesis program. More specifically, the evaluation focused on the impacts of input data errors...
Twenty-three red clover cultivars and accessions were grown in Boyd, KY, and Philomath, OR to evaluate their tolerance of northern anthracnose [NA; Kabatiella caulivora (Kirch.) Karak.] and drought, dry matter (DM) production, and their agro-morphological characteristics. The key research questions of this study were the influence of NA on yield...
The spawning habitat associated with fall chinook salmon (Oncorhynchus
tshawytscha) redd clusters was investigated in the Hanford Reach of the Columbia River.
A conceptual spawning habitat model is proposed that describes how geomorphic
features of river channels create hydraulic processes, including hyporheic flows, that
influence where salmon spawn in unconstrained...
Sardines and anchovies are small pelagic fishes that support important commercial fisheries around the world. This project reviews the inverse cyclic behavior in the abundance of these two stocks, which is a striking feature in many regions. In addition, the project used qualitative loop analysis techniques to analyze the feasible...
Sea level and wind data from coastal and island stations from
Buenaventura, Colombia (4°N) to Callao, Peru (12°S) have been
analyzed for the 1979-1984 time period, to describe the seasonal and
interannual variations in the characteristics of short time scale
variability (1-2 weeks). Auto- and cross spectral analyses are used...
Marine fish are subject to direct and indirect oceanographic variations operating at short and long time scales. In this study feeding habits and long-term growth condition of several groundfish species of the Pacific Northwest are examined to understand the relationship between variations in the fish's biological and life history components...
Nitrogen fertilization of seedling legumes is a controversial practice intended to provide N to the plant during periods when seed N, soil N, and N₂ fixation may not meet plant requirements; eg. prenodulation, postharvest, or in the event of an inoculation failure. Field experiments were conducted in 3 consecutive years...
A dynamic bioenergetic model for Steller sea lions (Eumetopias jubatus) was built using the STELLA simulation modeling system. The model is intended as an aid for the exploration of ecological questions regarding growth and survival of immature Steller sea lions (ages 1-3) living along the Oregon coast under different nutritional...
Species selection is a complex process that forage producers and land managers face. Accurate tools and educational materials are needed to help make the decision process easier. Crop simulation models are one tool that could be utilized to predict yield and potential financial return of various species. Two crop simulation...
If fisheries managers are to effectively manage commercially exploited fish populations, a basic understanding of the factors that influence fish distribution and abundance is required. In 2005, efforts to identify Essential Fish Habitat (EFH) for the 82 groundfish species managed by the Pacific Fishery Management Council along the West Coast...
:
_____________________________________________________________________
DavidB. Sampson
If fisheries managers are to effectively manage commercially exploited fish
Some amount of of consolidation has occurred under almost every individual quote program that has been implemented. In the most severe cases, fishing fleets have lost over 70% of their vessels. Because of the devastating impact such losses can have on fishing communities, it is vital that the potential for...
Lingcod are an overexploited fish species in the Pacific Northwest and although there has been extensive study of the habitat requirements of adults, particularly during spawning, relatively little is known regarding the habitat requirements of post-settlement juveniles. Many juvenile fish use structural components of habitat to alleviate the risk of...
Despite the fact that fishing is an inherently uncertain business, risk has rarely
been formally recognized in fisheries science or management. Few fishery
management plans include any form of risk assessment and those that do focus on
minimizing risk caused by uncertainty associated with markets and environmental
conditions. Fishermen's attitudes...
Fishermen's and managers' perceptions of fishery issues are an
important factor to consider when studying conflicts between the
two groups. According to theories of conflict management,
differences in perceptions may cause situations to be characterized
by misunderstanding and mistrust, and may add to the difficulties in
managing the conflict.
A...
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 Boleyn home located in Portland Oregon (latitude 45°) is evaluated based on monitoring data taken from 1977 to 1982. The Boleyn home is a two-story (plus basement) frame home. It takes benefit of passive solar gains and is equipped with an active solar system. The active solar system consists...
Centuries of continuous grain cropping in northern Africa have
reduced N levels in soils to a degree such that agricultural production
is now largely dependent upon nitrogen fertilizer. Through the
identification of highly effective legume and Rhizobium strain combinations,
the production of protein-rich livestock forage and green
manure can be...
Agrobacterium rhizogenes has been shown to cause root
proliferation and increased water use efficiency in
certain woody dicots. Root proliferation may be desirable
in herbaceous legumes as a means of increasing potential
sites for infection by Rhizobium species and subsequent
nodulation and nitrogen fixation. Thus, A. rhizogenes was
used to...
All animals that interact with fishing gear are not necessarily captured, and all animals that are captured are not necessarily retained. Fishing practices and gear configuration, management regulations, and markets dictate which animals ultimately are retained or discarded. The impact of a fishery and the efficacy of management regulations can...
:
_____________________________________________________________________
DavidB. Sampson
All animals that interact with fishing gear are not necessarily captured
Depletion-Based Stock Reduction Analysis (DB-SRA; Dick and MacCall, 2011) is a catch-only fisheries stock assessment model that has been developed to estimate an overfishing limit (OFL) in data-poor situations. DB-SRA projects the biomass trajectories of a stock by means of a catch time series and five parameters: the instantaneous, per...
Sampling error associated with estimates of species composition and age composition
of commercial groundfish landings in Oregon from 1989 to 1991 is documented to evaluate
the impact of variable landing data on fisheries management and monitoring programs. The
statistical reliability and bias associated with two multistage sampling designs are
investigated...
Field experiments were established in 1982 and 1983 on a Woodburn silt loam soil (Aquultic Argixeroll) to examine the effect of S fertilizer on dinitrogen fixation and dry matter yield of 10 week-old seedling alfalfa (Medicago sativa L. cv. 'Apollo'). Six levels of S fertilizer (0 to 67.2 kg S/ha)...
The Sultanate of Oman has 1700 km of coastline extending from the Arabian Gulf
south to the Arabian Sea. The demersal fish distributions and assemblages have not previously
been well defined. In winter, variations in the oceanography of the area are minimal. In
summer, however, the Arabian Sea is strongly...
When biogeochemical models are applied to large regions, the values of key model parameters are often unknowable. Through field and modeling studies, I examined the potential impact of such uncertainty on estimates of carbon cycling in western Oregon. I found that variation in key leaf traits could be interpreted ecologically,...
Tall fescue is a perennial forage grass widely used in areas not well-suited to perennial ryegrass due to climatic or edaphic stressors including drought and low or high pH. Although tall fescue has many agronomic attributes that make it well suited to a wide range of environments, it is lower...
This thesis evaluates the current break-and-burn ageing method for the southern stock (U.S. west coast) of sablefish (Anoplopoma fimbria). Differences in growth rates between the northern (north of Vancouver Island, BC) and southern stocks (south of Vancouver Island, BC) and results from a radiometric study conducted on fish from the...