Thesis (M.S.)--Washington State University, December 2007. / Includes bibliographical references.

Nuclear microsatellite DNA and mitochondrial DNA variation were examined in coho salmon (Oncorhynchus kisutch) and white sturgeon (Acipenser transmontanus) populations in order to address conservation issues in each species. In coho the goal was to examine genetic structure on a broad scale, in order to facilitate the conservation of genetic resources within the species. Coho salmon were widely sampled across their North American range. In white sturgeon the goal was to characterize population structure within the Fraser River, in order to identify biologically meaningful management units within that system. White sturgeon sampling was restricted to two watersheds (the Fraser and Columbia rivers), allowing much more thorough sampling than was done for coho. For both species, the use of mitochondrial and nuclear markers proved advantageous over examining either marker alone. The coho data revealed two levels of intraspecific variation, and gave the best indication to date regarding how genetic resources might be distributed within this species. The data is useful for protecting this species' ability to evolve. In contrast, the sturgeon data identified four regions within the Fraser River between which migration is limited. The sturgeon data, therefore, facilitate prevention of extirpation of local populations within the Fraser River. / Graduate

Memoria para optar al título de Ingeniero en Alimentos / La acuicultura en Chile en los últimos diez años ha registrado un radical proceso de expansión, constituyéndose en el sector de crecimiento más rápido dentro de la producción alimentaria mundial. En la actualidad la seguridad de los antioxidantes sintéticos está cuestionada y su uso en la industria alimentaria está severamente restringido por la ley, tanto en su aplicación como el nivel de uso, debido a la posible actividad como promotores cancerígenos y la actual tendencia a reemplazar los aditivos sintéticos por naturales, lo cual ha estimulado a evaluar la efectividad de estos compuestos naturales que poseen propiedades antioxidantes. Este estudio trata la variación de la calidad sensorial y propiedades funcionales del músculo del salmón coho (Oncorhynchus kisutch) cuando es alimentado con dietas adicionadas de antioxidantes naturales, tales como extracto de romero y/o α-tocoferol y conservado al estado congelado durante 18 meses. Para este estudio se empleó el uso de tres dietas, la dieta I que contenía etoxiquina y BHT (dieta control), la dieta II que contenía un exceso de tocoferoles libres y la dieta III que contenía α-tocoferol y extracto de romero. Se analizaron cinco individuos por dieta cada 3 meses durante 18 meses. El salmón periódicamente se evaluó sensorialmente en estado congelado descongelado y cocido, se analizó apariencia, color, olor y textura en el salmón descongelado y apariencia, color, olor, textura y sabor en salmón cocido. Las propiedades funcionales analizadas fueron capacidad de retención de agua, humedad exprimible, driping, gaping, ensayo de compresión y fuerza de cizalla tanto para el salmón crudo como cocido. Los descriptores sensoriales que presentaron diferencias significativas entre dietas y el tiempo de almacenamiento en el salmón crudo fueron: deshidratación del músculo, color escala Roche, olor típico, olor rancio, olor pútrido, elasticidad y goteo; para el salmón cocido los descriptores fueron: color escala lineal no estructurada, olor típico, olor rancio, sabor típico, sabor rancio, sabor pútrido y sabor oxidado. Estas diferencias no indicaron tendencias definidas entre las dietas estudiadas. Considerando las propiedades funcionales estudiadas, el gaping fue el parámetro determinante de la vida útil comercial del músculo de salmón alimentado con las tres dietas. El gaping de las dietas II y III aumentó paulatinamente sin llegar a un deterioro extremo, manteniendo hasta el mes 15 calidad Premium con grado 3 mientras que, la dieta control solamente alcanzó la calidad premium hasta el mes 9 (p≤0,05). Aunque se registraron diferencias significativas entre los distintos parámetros analizados, se concluye que estas diferencias no afectan la estabilidad del salmón durante el tiempo de almacenamiento, por lo tanto el reemplazo de antioxidantes naturales por antioxidantes sintéticos es viable como mejoramiento en la alimentación del salmón, en la alimentación humana y como una alternativa para mejorar la exportaciones de este producto a las principales regiones donde el salmón tiene una alta demanda.

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. / Science, Faculty of / Zoology, Department of / Graduate

Two similar salmonids, coho and steelhead, cohabit many coastal rivers of British Columbia. Field collections reveal that the distributions of underyearling coho and steelhead are similar along the length of these streams. However, the microhabitat distribution of the two species is different. In spring and summer, when population densities are high, coho occupy pools, trout occupy riffles. In autumn and winter, when numbers are lower, both species inhabit the pools. Nilsson (1956) stated that segregation (such as that shown by coho and trout in spring and summer) may be indicative of competition resulting from similar ecological demands. To test this hypothesis the distribution and behavior of coho and steelhead were compared in a stream aquarium at different seasons with gradients of light, cover, depth or depth/velocity and in experimental riffles and pools. Distributions, and preferences of the two species in the experimental environments were most similar in spring and summer, the seasons when segregation occurred in nature, and least similar in autumn and winter, the seasons when the two species occurred together in nature. Spring and summer segregation in the streams is probably the result of interaction which is produced by ecological similarities of the species and accentuated by dense populations and inherently high levels of aggressiveness. The species do not segregate in streams in winter because certain ecological demands are different, numbers are lower and inherent levels of aggressiveness are low. When the two species were together in the experimental riffle and pool environment, trout were aggressive and defended areas in riffles .but not in pools; coho were aggressive in pools but less inclined to defend space in the riffles. These differences in behavior probably account for the distribution of trout and coho in natural riffles and pools. The data support the basic contention of Nilsson (1956) and illustrate the role of behavior in segregation produced by competition for space. / Science, Faculty of / Zoology, Department of / Graduate

Rainbow trout {Oncorhynchus mykiss) and coho salmon (0. kisutch) produce males which mature at an abnormally early age. The objectives of this study were to critically describe the role of growth rate in early sexual maturation of male salmonids by monitoring growth rate and precocious sexual development in individually identified fish. Underyearling rainbow trout were individually identified using coded tags. These fish were reared at 9°C and 15°C and growth was monitored twice a month in both groups over a 9 month period starting January 24, 1989. The number of precocious males in the 9°C and 15°C groups were 11% and 18% respectively. Yearling coho salmon were similarly tagged, reared at ambient temperature, and monitored for growth over an 8 month period starting March 22nd, 1989. Ten percent of the coho salmon matured precociously. In both experiments there was a similar relationship between fast growth in early spring and precocious maturation. The growth rate of fish that matured declined in autumn relative to non-maturing individuals. Condition factor (length to weight relationship) was greater among those fish that matured precociously. Plasma growth hormone was monitored in the coho salmon. Most samples fell below the detection limits of the assay (1.5. to 3.0 ng/ml). A strategy to reduce the number of precocious males in cultured salmonids is suggested. / Land and Food Systems, Faculty of / Graduate

In the first experiment, sexually immature male and female coho salmon were exposed for 21 days to dietary DDT at a level of 10 or 100 parts per million (ppm), or to methoxychlor at a level of 100 ppm. Exposure to 100 ppm DDT was found to increase the level of liver microsomal Cytochrome P-450 from a control level of 1.32 ± .04 nmoles/1000 mg liver to a level of 1.98 ± .04 nmoles/1000 mg liver, a statistically significant difference (P<.001). None of the treatments were found to affect the hepato-somatic index. In the second experiment, liver slices from sexually maturing male and female coho salmon fed 100 ppm DDT for 21 days or a control diet were incubated with 4-C¹⁴-estradiol-17β in vitro. Metabolites produced were extracted with dichloromethane, separated by thin-layer chromatography and assayed using scintillation counting techniques. Produced in the incubation were estrone, estriol and one other unidentified polar metabolite. DDT treatment was found to significantly increase the amount of estriol and unidentified metabolite produced (P< .001). In the third experiment, sexually maturing male and female coho salmon fed 100 ppm DDT for 21 days or for 7 days or a control diet were injected with 625,500 dpm 4-C¹⁴-estradiol-17β and permitted to metabolize the hormone in vivo. Serial blood samples were extracted, chromatographed and subjected to scintillation counting techniques to obtain values for Metabolic Clearance Rate, Half-life Time and Volumes of Distribution of the injected steroid. It was found that ingestion of DDT had no significant effect upon any of these parameters (P<.001). The pattern of metabolites produced in vivo closely resembled that produced in vitro. The evidence presented in this study suggests that enhancement of the activity of the Mixed Function Oxidase system in coho salmon may occur upon ingestion of an organochlorine insecticide, but that the phenomenon may have little significance in vivo. / Science, Faculty of / Zoology, Department of / Graduate

The fry of the very similar salmonids, coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo gairdnerii), live in very close association with each other during their first year of life in fresh water. The present study was designed to measure the effects of competition between these species. Populations of different densities of coho and steelhead fry in four identical artificial stream-channels were studied. Observations were made on survival, growth rates, and some aspects of behavior. Among the various groups of fry, survival was apparently dependent upon interspecific factors; the presence of another similar species had no observable effect. Low-density populations survived well, even when another species was present at a high-density. Survival of the fish at high-densities was always depressed, even when the companion species was present at low density. Steelhead fry demonstrated a faster initial growth rate than the coho, enabling them to exceed the coho in growth despite the latter’s earlier hatching and consequent initial size advantage. Growth rates were inversely related to density, both inter- and intraspecific effects being noticeable. The two species tend to be spatially segregated, coho occupying positions in the middle and upper layers of the streams, and steelhead remaining close to the bottom. This stratification was reflected in their feeding behavior and diet. Emigration activity occurred to a greater degree among the coho than the steelhead. Emigrants of both species were observed, to undergo substantial weight loss subsequent to their disappearance from the stream-channels. It was concluded that coho and steelhead fry live in close association with one another without experiencing extensive interspecific competition. This is because of segregation of the species by having differing habitats, feeding habits, growth and survival rates, and consequent population dynamics. / Science, Faculty of / Zoology, Department of / Graduate

Scotts Creek, located in northern Santa Cruz County, maintains the southernmost persistent population of Central California Coast (CCC) Coho Salmon (endangered) in addition to CCC steelhead (threatened). Fisheries biologists believe overwinter mortality due to lack of refuge habitat is the primary factor limiting salmonid production. Instream rearing habitat may also be limiting, especially during drought years. The legacy effects of historic land use practices, including dredging, wood removal, and the construction of levees, continued to limit refuge and rearing opportunities. A restoration project was implemented to improve refuge and rearing opportunities for salmonids along lower Scotts Creek by removing portions of the deteriorating levee, grading new connections with existing off-channel features, enhancing tributary confluences, constructing alcove habitat features at the margins of the stream channel, and constructing large wood complexes (LWCs) instream. Novel restoration techniques were employed on an experimental basis. Whole in-situ alder trees were pushed into the stream channel with their root systems left partially intact to establish living key pieces. Individual log, boulder, and rootwad LWC components were attached together with couplers that permitted some freedom of independent movement among the individual components. LWCs were braced against live, standing trees and stabilized with boulder ballasts placed on the streambed, which eliminated excavation of the streambed/banks and the need to dewater or divert the stream during construction. Project performance, changes to physical habitat characteristics, and changes to stream morphology associated with implementation were monitored using habitat assessment methods derived from the California Department of Fish and Wildlife’s (CDFW) salmonid habitat survey protocol (Flosi et al. 2010), and topographic survey techniques and data analysis adapted from Columbia Habitat Monitoring Protocol (Bouwes et al. 2011). Preliminary results indicated that LWCs remained stable and functional. In addition, implementation of the restoration project increased pool frequency, low-flow pool volume, instream cover, frequency of instream, alcove, and off-channel refuge habitat features, and frequency of points of connectivity with the floodplain. Long-term monitoring will be required to determine the survivorship, decay rates, and overall persistence of alder recruits.

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