Steelhead populations support an economically valuable fishery in the Great Lakes region. Development of the region, resulting in land use changes and the introduction of hydropower, has affected the riverine habitat used by steelhead. I have developed an individual-based model of steelhead in the Manistee River, Michigan that simulates the long-term production of steelhead from the river. The model begins each year with a spawning population that produces redds for that year and then follows the offspring from each redd as individuals until they smolt one, two, or three years after spawning. Simulations run for ten-year periods. The simulated individuals are subjected to mortality from predation, starvation, and temperature extremes. Predation is a length-based mortality and is thereby affected by growth. Growth is determined by an individual's foraging success and bioenergetics. I conducted simulation experiments to examine the effect of changes in spawning numbers, temperature, and flow regime, on the number of individuals smolting in the river each year. Simulations reveal that the current flow regime and colder water temperatures are most beneficial for steelhead production and increasing the number of spawners does not increase steelhead production. The results also suggest that the young-of-the-year (YOY) stages have the greatest impact on steelhead production because the model showed no indication that steelhead life stages older than the YOY could compensate for density-related losses that occurred during the first year.

Gene expression profiles of tissues and cell-lines can be powerful tools for documenting the genetic response to a particular treatment, such as stressors. However, there is a paucity of information on the genetic stress response in the brain. Therefore, we attempted to profile gene expression in the brain of juvenile steelhead trout (Oncorhynchus mykiss) in response to stressors commonly encountered in aquaculture settings and similar to those encountered in hydropower dam mitigation efforts. We subjected fish to a combined out-of-water and low-water stressor totaling three hours. Plasma stress response factors indicate that fish were undergoing a physiological stress response after 3 hours of continuous stressor. We utilized suppression subtractive hybridization to identify cDNA fragments up- or down-regulated in the brain upon completion of the stressor. Forward and reverse subtractions, and sub-cloning of the purified PCR products yielded 59 clones all of which were sequenced. Sequenced cDNA fragments were subjected to BLASTn and BLASTx searches over the course of one year. Fragments fell into the following functional categories: those associated with ATP generation, signal transduction, ion transport, translational machinery, DNA packaging and mobilization, cell structure, and cDNA fragments with cryptic function. Of the 59, 12 were selected for further analysis, and 5 were confirmed to be differentially expressed by northern hybridization. The differentially expressed genes included cytochrome b, NADH dehydrogenase subunit 2, ATPsynthase subunit 6, a cDNA fragment with unknown function, and neuron specific gene 1. Our results present a first attempt to profile gene expression in the brain of fish and demonstrate the power of molecular tools at capturing large amounts of biological information without having to target any one particular gene. A gene expression profile of the brain consequent to stress provides a catalog of responses at a given time point. This catalog can then be used to isolate full-length cDNAs, localize mRNAs in the brain or other tissue, as probes to determine expression patterns and time courses of gene expression in other tissues, and for the quantification of cDNA molecules with real time PCR. / Graduation date: 2003

Thesis (Ph. D.)--University of Oregon, 2002. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 330-363). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 92-102). Also available on the World Wide Web.

Three experiments were designed to determine if and how steelhead trout, Oncorhynchus mykiss, may affect chinook salmon, O. tshawytscha, when they are confined together as in a raceway or on a barge. We observed groups of chinook and steelhead together and groups of only chinook in a behavioral experiment to determine if steelhead are aggressive and if their presence changed the behavior of chinook. Two physiological experiments were completed to determine if the loading of steelhead on top of chinook and if the introduction of odor from rainbow trout (steelhead not available) caused a change in plasma cortisol levels in chinook. It was found that chinook showed characteristics of a schooling species, while steelhead exhibited territory holding characteristics. Behavioral changes in chinook were observed when steelhead were present. Chinook grouped with steelhead reduced their movements, darted less, were attacked up to 16 times more often, and were found less frequently in the shade than groups of only chinook. Steelhead were found to establish territories and defend them with chases, charges, and nips. In attempts to establish territories and defend them, steelhead attacked chinook as often as they attacked other steelhead even though chinook showed little aggression toward steelhead. In a physiological experiment, chinook experienced the loading of salmonids into their tank. Chinook had higher levels of plasma cortisol at 2 and 32 hours after the loading of steelhead than chinook that were loaded with chinook or controls (no loading). A second physiological experiment with odor showed that chinook that received rainbow odor and those that received chinook odor had similar levels of plasma cortisol. Cortisol levels (two hours after the odor was introduced) were higher in chinook receiving either of the scented waters than in those that did not receive any odor. In conclusion, all three experiments indicated that the presence of juvenile steelhead trout affect juvenile chinook salmon behavior and physiology. / Graduation date: 1998

Newly emerged steelhead fry (Oncorhynchus mvkiss) of hatchery and wild origins were studied in laboratory stream channels and natural streams. Objectives of the study were to determine if and how earlier emerging hatchery fry influence the emigration, realized densities, growth, habitat use, social structure, and activity patterns of localized populations of wild steelhead fry when the hatchery fry have a competitive advantage conferred by larger size and prior residence. During 1986 and 1987, the above variables were observed daily among hatchery and wild steelhead fry in laboratory stream channels for 8 weeks following emergence in June. The habitat use and social activities for fry of both origins were observed weekly in natural stream reaches from June through August in 1987 to corroborate lab findings. In lab channels, both hatchery and wild fry received 2 treatments: living alone (allopatry) and living together (sympatry). In the lab, fry of hatchery origin emerged 7 to 10 d prior to wild fry and remained larger in size during the 8 weeks of study both years. In natural stream reaches, fry of each origin were observed only in allopatric situations. Wild fry in the field emerged from natural redds while hatchery fry were released in stream reaches as unfed, newly emerged (swim-up) fry. Hatchery and wild fry in lab sections were found to be very similar in their emigration rates, distances to nearest neighbor, growth rates, and use of habitat. Both fry types, regardless of treatment or environment (lab or field), established similar stable social structure and used the same types of aggressive acts. Among all lab groups, once a fry became dominant, it retained that social status to the end of the study period. Significant differences (P<.05 both years) among comparison tests were: 1) in allopatric lab sections, wild fry maintained larger densities than hatchery fry, 2) in sympatry, hatchery fry had a greater tendency to establish stable focal points and social hierarchies more readily, defend larger areas, have better condition, prefer pools with overhead cover more frequently, be more aggressive, and reach stable densities more quickly than the wild fry, 3) fewer hatchery fry in sympatry maintained nomadic positions than wild fry in both treatments, 4) in sympatry, hatchery fry directed more acts of overt aggression toward wild fry than other hatchery fry, 5) wild fry in sympatry usually used defensive or less offensive acts of aggression when interacting with other fry, 6) fry of both origins in natural stream reaches maintained greater distances to their nearest neighbor than fry in allopatric lab sections, 7) dominant hatchery fry in both treatments maintained larger focal areas than subdominant fry, 8) hatchery fry maintained longer lengths than wild fry through the duration of the study, and 9) hatchery fry were more aggressive in sympatry than in allopatry. Potential differences (P<.05 in one year and P<.1 in the other year) were: 1) wild fry in sympatry had lower realized densities, maintained smaller focal areas, had greater proportions of nomadic individuals, and established stable social hierarchies slower than wild fry in allopatric lab sections, 2) wild fry in sympatry had poorer condition than all other fry groups in lab sections, 3) in sympatry, wild fry were the recipients of the majority of aggressive acts perpetrated by hatchery fry and other wild fry and usually assumed the subordinate positions within the social hierarchy, 4) all fry in the lab showed a high preference for pools with overhead cover and low preference for gravel and fines and run areas, and 5) wild fry in allopatric lab sections were more socially active than hatchery fry while the reverse was observed in the natural streams. Any influences that could be attributed to inherent differences between stock origins were probably masked by size differences between fry types. The study would have been more complete had I included sympatric lab sections where wild fry emerged first and where fry types emerged simultaneously, and sympatric reaches in natural streams. Results were further confounded by the limited number of wild adults used for broodstock in the lab segment of this study. Progeny produced from so few adults (5 adults of each sex each year) would have very limited genotypic variation compared to what occurs in natural streams. This may partially explain why some findings from lab sections and natural stream reaches differed. Likewise, genotypic expression among wild fry in lab sections may have varied greatly between years. This could explain differences found between years in behavior of wild fry in similar lab treatments. Although this study does not simulate all possible scenarios, results support suspicions that introductions of hatchery fry of larger size and earlier emergence into streams containing wild stocks could disrupt the social structure and negatively influence the realized densities, spatial distribution, growth, and behavior of wild juveniles in recipient streams. / Graduation date: 1991

Steelhead and rainbow trout are common names for marine-migratory (anadromous) and freshwater-resident forms of Oncorhynchus mykiss, a partially migratory salmonid fish. Anadromous and resident forms are sympatric and can produce offspring with a life history different from their own (i.e., steelhead parents can produce rainbow trout offspring and vice versa). The expression of these alternative life histories is a plastic response to individual patterns of energy acquisition, assimilation, and allocation during juvenile life stages. Individual performance during early stream life is of particular interest because of potential carry-over effects on subsequent growth and developmental trajectories. In a series of experiments in laboratory streams, I determined the influence of individual variation in energy metabolism on behavior, growth, and life-history expression in O. mykiss. Individual variation in energy metabolism was a strong predictor of feeding territory acquisition by juvenile fish during the transition from dependence on maternal provisioning of egg yolk reserves to independent feeding. Feeding territory acquisition was positively associated with standard metabolic rate (SMR) under conditions of an abundant and predictable food supply. When the density of intraspecific competitors was manipulated, the association between SMR and territory acquisition was strongest at intermediate stocking densities, moderate at the highest stocking densities, and weakest at the lowest stocking densities. However, reducing the spatial predictability of food resources within streams reversed the influence of SMR on competitive outcomes. These experiments determined that variation in ecological conditions during early life stages imposes different selection regimes on juvenile O. mykiss and results in physiological divergence among cohorts. Subsequent rearing experiments determined that behavioral dominance influences rates of anadromy and freshwater maturation, most likely through the association between SMR and territory acquisition. In addition to the effects of behavioral dominance, I observed a significant influence of sex, rearing temperature, and individual growth trajectories on the expression of anadromy and freshwater maturation. Partially migratory populations of O. mykiss maintain an exceptionally diverse portfolio of life-history strategies. Results from this work lend insight into a suite of behavioral and physiological processes influencing individual life histories. / Graduation date: 2013

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 80-94). Also available on the World Wide Web.

Currently, little is known about the demographics of the Oncorhynchus mykiss irideus, or steelhead trout, populations in San Luis Obispo County. Specifically, demographic information including length, age, and condition when first leaving a watershed for the open ocean is lacking. This thesis takes a closer look at a biological and environmental data collected by the California Department of Fish and Game Central Coast Steelhead and Coho Salmon project under the direction of Associate Biologist Jennifer Nelson. The main goal of this thesis is to analyze demographic and habitat data from the steelhead populations of two northern San Luis Obispo county coastal streams, San Simeon and Santa Rosa Creeks. Habitat mapping surveys were conducted on each stream in order to identify suitable habitat for various steelhead life stages. The data generated from the habitat mapping surveys was compared between the two creeks over the two different survey years (1993 and 2005). The results of these surveys showed that habitat types have changed on San Simeon Creek between survey years while Santa Rosa Creek appeared to remain the same. Biological inventory methods were conducted on the populations of O. m. irideus in San Simeon and Santa Rosa Creeks during the years of 1993 and 2005. There were very few observations of steelhead moving downstream on both survey creeks in 1993. During the 2005 out-migrant trapping season, the data revealed that non-smolting fish are moving downstream in the watershed in addition to smolting fish. There is evidence that age 1+ and 2+ fish make up the majority of downstream migrants. Older, larger fish tend to migrate downstream earlier in the trapping season. Fork length – weight relationships are not significant between steelhead sampled from out-migrant traps, while those sampled throughout the watersheds by means of electrofishing were different between creeks. Percent frequency distribution of electrofished steelhead reveal that steelhead sampled in 2005 have a similar distribution of total lengths between creeks, where as those sampled in 1993 have a slightly different distribution from each other. Further analysis of steelhead scales sampled from the populations on San Simeon and Santa Rosa Creeks in 2005 gave greater insight into the growth of these fish. In most cases, steelhead from Santa Rosa Creek have greater growth increments and higher circuli counts per annuli than those surveyed from San Simeon Creek. The majority of scale samples analyzed showed growth since the last annuli mark suggesting an increase in growth over the winter months. The average number of circuli to the first annuli is significantly different between watersheds, as is the relationship between fork length and scale radius. Analyzing steelhead demographics is important to understanding the life history pattern of steelhead in the South Central California Coast Distinct Population Segment (DPS). Surveys that monitor environmental conditions and habitat help to identify potential limiting factors and risks to steelhead populations. The results of this thesis present such data in hopes to promote continued research and efficient management practices of steelhead trout populations in San Luis Obispo County.