Graduation date: 1991

Thesis (Ph. D.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 126-139). Also available on the World Wide Web.

An integrated laboratory and field approach was used to study the behaviour and ecology of Pacific salmon (genus Oncorhynchus) alevins in the gravel. The hypothesis tested was that these yolk sac fry move throughout the gravel prior to emergence, that this movement has both lateral and vertical components, and that changes in the physical or biological environment will alter certain parameters of subgravel behaviour. Eyed chum salmon (0. keta) eggs were buried in incubation channels at Robertson Creek, B. C. Eight experimental treatments were chosen, utilizing two gravel sizes, two burial depths and two planting densities. The fry were captured at emergence by means of specially designed traps that allowed determination of degree of lateral movement, pattern of emergence and survival to emergence. The fry were also sampled for condition (weight-length ratio) at the time of emergence. In the larger gravel, survival was greater, lateral movement was increased, and initial emergence was earlier. At the greater burial depth the emergence period was longer. At the greater burial density initial emergence was earlier. Condition at emergence was the same in all treatments. The behaviour of coho salmon (0. kisutch) alevins was examined in specially constructed aquaria, where light and flow conditions were as natural as possible. The same environmental factors were varied as in the field. In addition to a general description of alevin behaviour, detailed analyses were carried out on: vertical and lateral movement, orientation, spatial distribution, condition, survival and pattern of emergence. In the larger gravel vertical and lateral movements were increased, survival was higher, area utilization was greater and condition at emergence was poorer. At the greater burial depth lateral movement towards the outlet was increased and initial emergence was earlier. Vertical movement was decreased because more fry were trapped within the gravel. At the higher density the alevins moved farther towards the inlet. The mean area occupied per alevin was unchanged by density and suggests competition within the gravel. The orientation of the alevins is discussed in relation to light and current. The results indicate that larger gravel is better than smaller gravel for the incubation of Pacific salmon. Burial depth seems unimportant, but should be great enough to prevent predation. The question of optimum density requires further study. Emergence patterns may apparently be modified through environmental control. / Science, Faculty of / Zoology, Department of / Graduate

Memoria para optar al título de Ingeniero en Alimentos / El hielo líquido es un novedoso método de conservación de productos marinos que presenta una serie de ventajas en comparación al tratamiento con hielo en escamas, entre las cuales se destacan un rápido enfriamiento, menores .temperaturas y menor daño superficial al pescado. Este estudio tiene como objetivo comparar el efecto de esta técnica frente a la del hielo en escamas en salmon Coho (Oncorhynchus kisutch) cocido y en conserva sobre sus propiedades físicas, químicas y sensoriales. Se analizaron muestras cocidas y enlatadas conservadas en ambos tipos de hielo durante 0, 5 y 9 días. En las muestras enlatadas se analizó el músculo y el líquido de cobertura. Se realizaron análisis físicos: test de cizalla y color instrumental; análisis químicos: pH e índice de anisidina y evaluación sensorial por medio del test descriptivo cuantitativo. Para el salmón cocido, los resultados mostraron que el hielo líquido fue mejor evaluado en el test de cizalla y pH. En el filete de salmón en conserva obtuvo mejores resultados en firmeza (test de cizalla) y luminosidad (L*) medida en forma instrumental y sensorial. Por último en el aceite de cobertura, la evaluación sensorial indicó que presentaba una menor turbidez, menor cantidad de partículas en suspensión y mayor luminosidad

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 93-102). Also available on the World Wide Web.

Coho salmon (Oncorhynchus kisutch) rely on unique habitats during the winter season, which may dictate how much individuals may grow and when migration from freshwater rearing habitat to the ocean occurs. Here I analyze movement timing and growth patterns for coho salmon through a field-based study and a literature review. For the field portion, I examined hatchery-stocked juvenile coho salmon across four stream basins in the Russian River watershed, California to determine the relative importance of climate, landscape, and fish size metrics in predicting movement and growth patterns over a winter rearing and spring smolt outmigration time period (December 2014-June 2015). I observed three unique movement strategies: winter parr movement, spring smolt movement, and inter-tributary movement. Movement was predicted in relation to daily temperature and precipitation, followed by in-stream and upslope basin conditions in random forest modeling. Specifically, fish that moved later were associated with basins that contained higher productivity and low-gradient floodplain habitats, while fish that moved earlier came from streams that lacked invertebrate prey and had limited low-gradient rearing habitat. Fish size and timing of movement were the primary predictors of growth, with relatively larger fish in the spring growing faster than fish that were relatively smaller prior to winter. These relationships suggest that hatchery-release fish are still highly influenced by environmental conditions once released, especially in terms of initial seasonal movement, and that watershed conditions should be considered when utilizing hatchery-rearing programs to supplement wild fish populations. In North America, coho salmon populations are distributed from Alaska through California, and may exhibit unique movement and growth patterns in relationship to population-scale vulnerability (Endangered Species Act listing), basin area, and availability and types of rearing habitat. For the second part of my thesis, I conducted a literature review to assess what factors are commonly considered in predicting movement and growth patterns for these fish, as well as the types (season and life stage) and number of movement strategies reported. Eighteen studies were summarized, of which sixteen identified unique movement strategies, ranging from one to four. Despite a wide range of basin areas and latitudes, winter parr and spring smolt movements were commonly observed, with authors primarily relating these behaviors to in-stream habitat and fish size metrics. Additionally, growth was linked positively and primarily with off-channel winter rearing, which may outweigh the importance of fish size in predicting growth when high quality rearing habitats are available during the winter season. Recognizing movement timing diversity and its drivers can help recover threatened coho salmon populations. More widely distributed populations may have unique phenotypic expressions based on localized genetic and environmental interactions, increasing diversity and overall stability across the population, a concept known as the portfolio effect. Understanding fish-habitat relationships can aid recovery efforts by providing a framework of climatic and watershed conditions that support unique behaviors, even in already severely limited populations.

Determining the physical and biological habitat variables that influence the abundance of juvenile salmonids in British Columbia streams will improve management practices. Habitat models are tools that provide insight into organisms’ habitat needs and provide a more efficient mechanism for estimating population abundance than direct measurement. Models have been developed for salmonids in other jurisdictions, but very few have included invertebrate drift (a primary food source for juvenile salmonids) as a predictive variable. This is because temporal and spatial variation of drift abundance are widely assumed to be so high that drift cannot be reliably estimated without unreasonable effort. This thesis investigates the temporal and spatial variability of invertebrate drift and the impact of its inclusion in habitat models for juvenile salmonid abundance in two chapters. The first objective of the first chapter was to evaluate the temporal variability of invertebrate drift by comparing the seasonal and day-to-day variation in drift abundance to spatial variation within and between sites. The second objective was to develop predictive models for invertebrate drift abundance. Aquatic, terrestrial and total invertebrate drift abundances varied primarily between sites and very little between days or months at the same site, indicating that a single day of sampling is sufficient to assess drift abundance for comparison among sites. The abundance of invertebrate drift was related to productivity- and flow-related habitat variables. The objectives of the second chapter were to develop predictive models for juvenile salmonid abundance in southwestern BC using physical and biological habitat variables, to determine whether habitat variables differ between the Coast and Interior regions of BC, to determine the contribution of invertebrate drift to the relative predictive ability of the models, and to determine cost:benefit ratios for the predictive models and their component variables. The final models for predicting abundance of all young-of-year salmonids combined, and rainbow trout (Oncorhynchus mykiss) and coho salmon (O. kisutch) individually, included variables related to stream structure and productivity, and the models for rainbow and coho showed regional differences. Invertebrate drift did not improve model fit.

Determining the physical and biological habitat variables that influence the abundance of juvenile salmonids in British Columbia streams will improve management practices. Habitat models are tools that provide insight into organisms’ habitat needs and provide a more efficient mechanism for estimating population abundance than direct measurement. Models have been developed for salmonids in other jurisdictions, but very few have included invertebrate drift (a primary food source for juvenile salmonids) as a predictive variable. This is because temporal and spatial variation of drift abundance are widely assumed to be so high that drift cannot be reliably estimated without unreasonable effort. This thesis investigates the temporal and spatial variability of invertebrate drift and the impact of its inclusion in habitat models for juvenile salmonid abundance in two chapters. The first objective of the first chapter was to evaluate the temporal variability of invertebrate drift by comparing the seasonal and day-to-day variation in drift abundance to spatial variation within and between sites. The second objective was to develop predictive models for invertebrate drift abundance. Aquatic, terrestrial and total invertebrate drift abundances varied primarily between sites and very little between days or months at the same site, indicating that a single day of sampling is sufficient to assess drift abundance for comparison among sites. The abundance of invertebrate drift was related to productivity- and flow-related habitat variables. The objectives of the second chapter were to develop predictive models for juvenile salmonid abundance in southwestern BC using physical and biological habitat variables, to determine whether habitat variables differ between the Coast and Interior regions of BC, to determine the contribution of invertebrate drift to the relative predictive ability of the models, and to determine cost:benefit ratios for the predictive models and their component variables. The final models for predicting abundance of all young-of-year salmonids combined, and rainbow trout (Oncorhynchus mykiss) and coho salmon (O. kisutch) individually, included variables related to stream structure and productivity, and the models for rainbow and coho showed regional differences. Invertebrate drift did not improve model fit.

Coastal cutthroat trout (Oncorhynchus clarkii clarkii) are the apex predator in the Capilano Reservoir. This thesis investigates cutthroat predation via bioenergetic modelling and demography, and genetic analysis of hybridization with coastal rainbow / steelhead trout (O. mykiss irideus). The bioenergetics model, based on stomach content analyses, reservoir temperature and growth rates, in conjunction with predator abundance, estimates that adult trout in the reservoir consumed 6.4% of coho (O. kisutch) smolt production in 2010. No evidence of cutthroat predation on juvenile steelhead out-migrants was detected, and a gape prey maximum of 36% of predator body length was found. Moderate hybridization rates between cutthroat and rainbow trout were detected, as well as previously unknown pure strains of adult rainbow trout in reservoir waters, indicating reservoir residualization. Cutthroat trout are currently a 'second tier' management species in the Capilano Watershed, and greater understanding and appreciation of their adfluvial-lacustrine life history will facilitate informed decision-making for trout conservation and restoration, and coho management in the reservoir and the Capilano Watershed.

Thesis (M.S.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliographical references (leaves 88-100). Also available via the World Wide Web.