Birds perform valuable ecological functions and are useful environmental indicators. Avian distributions and diversity are predicted to change over the next 50 years. Little information exists on the role of local and regional conditions in fluctuations of avian communities over time. Historic datasets present a legacy of information that helps...
The Cackling goose (Branta hutchinsii minima) population has increased from a low of 20,000 in 1984 to the current population of 220,000-300,000 (Stehn 2012, Sanders 2013). As the Cackling goose population began to recover in the late 1990s, the majority of the population relocated from wintering in California to the...
The mechanisms of mortality during critical life stages of fish are not well-understood and, for many species, it is not clear if the mechanisms are similar for naturally and artificially propagated individuals. For Chinook salmon (Oncorhynchus tshawytscha), natural fish potentially face negative interactions, such as competition, and survival disadvantages, such...
Nest sites of reticulate sculpin (Cottus perplexus) were located in two stream reaches, one from a basalt basin and one from a sandstone basin. Stream reaches were similar in gradient, basin area, elevation, climate, and riparian vegetation but differed in biologic community structure and substrate characteristics. An electivity index was...
Many factors should be considered before selecting a graduate program to attend. Graduate education can be expensive, so financial and health care benefits offered by a department or college should be considered when selecting a graduate program. A majority of fisheries graduate students recently surveyed believed that financial aspects should...
We used radio and acoustic telemetry to study the behavior and survival of wild steelhead trout (Oncorhynchus mykiss) and hatchery coho salmon (Oncorhynchus kisutch) and steelhead outmigrants in a small coastal estuary during two years. Survival was generally low for hatchery fish but more variable, both within and between years,...
Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are...
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...
Recent comparative studies across sex-changing animals have found that the relative size and age at sex change are strikingly invariant. In particular, 91%–97% of the variation in size at sex change across species can be explained by the simple rule that individuals change sex when they reach 72% of their...
The population of Catostomus rimiculus from Jenny Creek basin is identified as a dwarfed derivative of the normally much larger C. rimiculus from the Klamath and Rogue River systems. C. rimiculus in Jenny Creek basin are separated from those in the Klamath by a series of 3-10m waterfalls resulting from...
Understanding food webs is fundamental in conserving endangered species and maintaining healthy ecosystem function, particularly in desert spring systems. We identified dominant energy sources in the Muddy River Warm Springs area, Clark County, NV using carbon and nitrogen natural abundance stable isotope analyses. We examined isotopic signatures of specific macroinvertebrate...
A group of trout that reside in streams of the desiccating lake
basins of southeastern Oregon differ markedly from other known
Salmo. Known commonly as the red-band trout, this fish was subjected
to chromosome analysis for comparison with other species of
western North American Salmo. The karyotype of the red-banded...
New approaches are needed to quantify and understand spatial patterns of stream fishes and their environment. Concepts in riverine ecology emphasize the importance of thermal zones and gradual longitudinal changes in physical habitat and biota, but little is known about spatial variability within the river continuum. I present a conceptual...
Mediterranean-climate regions (med-regions) are global hotspots of endemism 40 facing mounting environmental threats associated with human-related activities, including the ecological impacts associated with non-native species introductions. We review freshwater fish introductions across med-regions to evaluate the influences of non-native fishes on the biogeography of taxonomic and functional diversity. Our synthesis...
Classification of Streams and stream habitats is useful for research involving establishment of monitoring stations, determining local impacts of land use practices, generalization from site-specific data, and assessment of basin-wide, cumulative impacts of human activities on streams and their biota. This thesis presents a framework for a hierarchical classification system,...
A critical seasonal event for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which adults migrate from the ocean to breed in freshwater. We investigated whether allelic variation at the circadian rhythm genes, OtsClock1a and OtsClock1b, underlies genetic control of migration timing among 42 populations in North America. We...
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...
The genotype frequencies of one-year-old oyster spat
(Crassostrea gigas) from parents of known genotype, are compared
to the frequencies expected with Mendelian inheritance. The genotypes
are characterized at three enzyme loci, Aspartate amino-transferase
(AAT), Phosphohexose isomerase (PHI) and Leucine
aminopeptidase (LAP), and a general protein locus. In this study
expression...
The distribution and range of the greater sage-grouse Centrocercus urophasianus have been reduced by 56% since the European settlement of western North America. Although there is an unprecedented effort to conserve the species, there is still considerable debate about the vegetation composition and structure required for nesting and brood-rearing habitat....
The distribution and range of lesser prairie-chicken (Tympanuchus pallidicinctus) has been reduced by >90% since European settlement of the Great Plains of North America. Currently, lesser prairie-chickens occupy 3 general vegetation communities: sand sagebrush (Artemisia filifolia), sand shinnery oak (Quercus havardii), and mixed-grass prairies juxtaposed with Conservation Reserve Program grasslands....
To understand the influence of selective harvesting on
the adaptive capacity of fish populations in changing
environments, a computer simulation model was developed. In
the model, hypothetical populations were composed of five
different life histories, which were genetically determined.
Each life history type had its own rate of survival and...
The research involved development of two ecological
simulation models to explain the complex dimensionality of
chinook salmon (Oncorhynchus tshawytscha) life history
structure (represented by the age composition of the
spawning stock) and management difficulties entailed in the
complexity.
Since different sizes of chinook salmon are thought to
adapt differently to...
This thesis focuses upon whether stressful aspects of an organism's environment are reflected by that organism's shape. It presents an application of the powerful thin-plate spline and relative warp methods from morphometric analysis to demonstrate the overall utility of morphometrics in detecting environmental stress in an estuarine flatfish, the English...
Initially, components of an aquatic food web were examined to study impacts of recreational use on the aquatic ecology of Quartzville Creek, Oregon in 1995 and 1996. Measurements of the food web components consisted of observations of harlequin ducks (Histrionicus histrionicus), visual counts of the larval caddisfly Dicosmoecus gilvipes, benthic...
Four streams-Clear Fork, Lost Creek, Camp Creek and Still Creek-in northwestern Oregon's Sandy River Basin were monitored for temperature, dissolved oxygen levels, and fecal bacterial concentrations in a multi-year analysis examining stream health for recreational users and anchor habitat for Pacific Salmon. Temperatures were recorded using micro -T temperature loggers...
Western Atlantic synodontid species were studied as part of an ongoing effort to reanalyze Caribbean shorefish diversity. A neighbor-joining tree constructed from cytochrome c oxidase I (COI) data revealed 2 highly divergent genetic lineages within both Synodus intermedius (Agassiz, 1829) (Sand Diver) and S. foetens (Linnaeus, 1766) (Inshore Lizardfish). A...
An aspect of the genetic structure of coastal Oregon steelhead was
explored and found to gradually change in a north to south pattern for the
allelic frequencies of several enzymes. Isocitrate dehydrogenase and
superoxide dehydrogenase were the clearest examples of this pattern of
variation. This pattern was most evident in...
The rainbow trout population in Elder Creek, Oregon was
studied between June 1965 and November 1966. The physical characteristics
of the stream during the summer season were described.
Rainbow trout were captured in each of three sections on the stream
by electrofishing and were tagged and measured. Population size,
mortality,...
Between 1970 and 1974, data were collected on the distribution and biology of the spotted owl (Strix occidentalis) in Oregon. One-hundred and sixteen pairs and seven single birds were located. Spotted owls occurred throughout the mountains of western Oregon and on the east slope of the Cascade Range at least...
Marine provinces, founded on contrasting floras or faunas, have been recognized for more than 150 years but were not consistently defined by endemism until 1974. At that time, provinces were based on at least a 10% endemism and nested within biogeographic regions that covered large geographic areas with contrasting biotic...
Field collections in the Southern Gulf of Oman and the Northwestern Arabian Sea, and
examination of museum collections from this study area, yielded 7 genera and 33 species
of apogonid fishes. Twenty one species of Apogon, one Archamia, four Cheilodipterus,
three Fowleria, one Rhabdamia, two Siphamia, and one Holapogon are...
Descriptions and distributions are given of 28 species of
Liparidae occurring or possibly occurring below 200 m between San
Francisco and northern Vancouver Island, with keys for their identifications.
Nine genera are included: Careproctus, Elassodiscus,
Lipariscus, Nectoliparis, Rhinoliparis, Acantholiparis, Paraliparis,
and two new genera are described, Odontoliparis and Osteodiscus.
Eight...
The taxonomic placement of Gadopsidae is discussed and an evaluation of its osteological relationships with related families is given. Similarities to the more primitive genera of the trachinoids, notothenioids, and uranoscopoids are noted and the inclusion of Gadopsidae in the Trachinoidae is recommended. A description of the geological history of...
Research on cetacean foraging ecology is central to our understanding of their spatial and behavioral ecology. Yet, functional mechanisms by which cetaceans detect prey across different scales remain unclear. Here, I postulate that cetaceans utilize a scale-dependent, multimodal sensory system to assess and increase prey encounters. I review the literature...
Conceptually, the dynamics of wood in streams can be viewed in terms of input and in-channel processes. Input processes are associated with both the riparian (tree fall, bank cutting, windthrow) and upslope forests (mass failures). In-channel processes include log breakage, movement, and decomposition. A mechanistic view of these processes is...
The influence of land use on potential fates of nitrate (NO3-) in stream ecosystems, ranging from denitrification to storage in organic matter, has not been documented extensively. Here, we describe the Pacific Northwest component of Lotic Intersite Nitrogen eXperiment, phase II (LINX II) to examine how land-use setting influences fates...
A generalized mathematical model of ecosystems is
developed. The model begins with the general class of
systems known as state-determined systems, in which the
time-derivative of each state variable is a function of some
subset of the set of all system state variables and
.environmental parameters. A formal basis is...
Adequate management and scientific investigation of ecosystems
depends on classification of landscape systems based on all significant
bio-physical and associated cultural properties. The present
classification is a hierarchical systems design that can be modeled in
terms of a natural system interacting with its level-specific
environment. A watershed system in this...
A theoretical framework for economic fishery management was
developed. Extensive isocline analysis of a general fishery model
yielded a detailed look at the possible equilibrium behavior of a
system that was allowed to vary in terms of the levels of its
environmental parameters, its composition, and the response functions
governing...
Twentieth century commercial whaling drastically reduced the abundance of great whale populations in the Southern Ocean. Exploitation began on the south Atlantic island of South Georgia, where catch records account for over 175,000 whales killed. Modern whaling within the Southern Ocean depleted populations rapidly, and by 1966, hunting blue whales...
Patterns of seasonal abundance of harbor seals at Netarts and Tillamook Bays, Oregon, were documented by recording numbers of seals hauling out on tidally exposed sand flats in both bays. Harbor seal abundance at Tillamook Bay peaked during pupping (May-June) and molting (August) periods, while peak abundance at Netarts Bay...
Fisheries management that is based on quantitative assessment has commonly relied on estimating the unfished biomass of a fished stock to compare current and historical population size. Developing predictive models for this requires many years of catch and abundance data. Smaller, new, or mainly recreational fisheries may not have the...