Headwater streams in the Oregon Coastal Range are subject to drastic fluctuations in flow and temperature because of the changing seasonality of a Mediterranean climate. In response to these changes, stream fishes exhibit a variety of movement patterns. Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) have evolved an assortment of life...
This thesis provides the first general description of the natural variation in age
structure, growth rates, and survival in headwater populations of coastal cutthroat
trout Oncorhynchus clarkii clarkii from western Oregon, and a subsequent
synthesis of these life-history characteristics across the range of the subspecies.
Age, growth, and survival were...
Anadromous coastal cutthroat trout Oncorhynchus clarkii clarkii may be highly dependent on estuaries, passing through them multiple times during their lifetime. However, few studies have investigated estuarine use by coastal cutthroat trout and it is often thought that estuaries serve primarily as migration corridors rather than rearing areas. We used...
Biological invasions are the second largest threat to biodiversity following habitat loss, and studying invasions has been a focus of ecological the past two decades. Despite the intense research, many basic questions remain empirically unanswered, particularly in the realm of behavior. The purpose of this research was to explore the...
The evolution and maintenance of multiple phenotypes within populations is an interesting evolutionary and ecological question, and is becoming increasingly important for the restoration and conservation of partially migratory species. In particular, why individuals adopt a particular phenotype has been the focus of numerous research efforts. In the partially migratory...
Multiple analytical techniques were used to evaluate the impact of multiple parasite species on
the mortality of threatened juvenile coho salmon (Oncorhynchus kisutch) from the West Fork Smith
River, Oregon, USA. We also proposed a novel parsimonious mathematical representation of
macroparasite distribution, congestion rate, which i) is easier to use...
Alternative male phenotypes in salmonine fishes arise from individuals that mature as larger and older anadromous marine-migrants or as smaller and younger freshwater residents. To better understand the processes influencing the expression of these phenotypes we examined the influences of growth in length (fork length) and whole body lipid content...
We described and predicted spatial variation in marine migration (anadromy) of female Oncorhynchus mykiss in the John Day River watershed, Oregon. We collected 149 juvenile O. mykiss across 72 sites and identified locations used by anadromous females by assigning maternal origin (anadromous versus non-anadromous) to each juvenile. These assignments used...
Diseases caused by parasites are recognized as significant sources of mortality in wild fish populations. I assessed the impacts of multispecies parasitism on a threatened stock of juvenile coho salmon (Oncorhynchus kisutch). A crucial prerequisite to this research was proper identification of parasites, which can be difficult for species lacking...