Thesis (Ph. D.)--University of Washington, 1994. / Vita. Includes bibliographical references (leaves [181]-194).

Anadromous fish populations in the Pacific Northwest have undergone substantial change throughout the past century. Historical periods of over-harvest and the construction of numerous dams throughout the region have contributed to declines in the runs of naturally spawning stocks. Management efforts to rebuild fish populations have focused on the restriction of harvest activities and the release of hatchery-reared salmon. A microcomputer simulation model is developed to estimate the economic impacts of management alternatives. In it, fish are passed throughout a network of nodes, according to parameters governing mortality and harvest. These parameters, and the node structure itself, are provided to the model by a user-specified input file. As a result, the model affords flexibility in meeting the modeling needs of differing salmonid stocks. The model's economic assessment capabilities are demonstrated through a case study of Rogue River spring chinook. Results of this exercise include estimates for the impacts of dam construction, hatchery releases, and changes in ocean and river harvest policies on the social value derived from harvest activities. The research also examines the redistribution of economic benefits associated with these policies. The impact of a recently constructed dam upon spring chinook fishermen is estimated at a loss of more than $10,600,000 over thirty years, given no hatchery supplementation. Current hatchery programs have mitigated the loss to fishermen, but whether they also offset their operating costs depends upon the particular harvest values employed. The value of providing an additional wild spawner to the basin is estimated to be roughly $300. Examination of various harvest alternatives indicates that restrictions placed on the commercial ocean fishery would be more successful in increasing the present value of harvests than would similar restrictions in the sport fishery. An important factor in this outcome is the higher value attributed to sport catch by currently accepted methods of valuation. Suggestions are made for improvements to the simulation model and the availability of information for use with it. Foremost among these is the need for improved specification of the marginal social value derived from salmon harvested in commercial and recreational fisheries. / Graduation date: 1987

Thesis (Ph. D.)--University of Washington, 1994. / Vita. Includes bibliographical references (leaves [191]-210).

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

The effects of short term exposures to sublethal doses of mercuric chloride were studied using species of anadromous fish. Aspects of grou/th and behaviour u/ere used as indicators of physiological and psychological malfunctions due to mercurialism. The characteristic migration tendencies ( upstream or downstream ) of Lower Babine and Fulton River alevins were tested in experimental laboratory channels. The were conducted in a chamber in which a day, dawn through dusk, could be simulated. Each stock was divided into three groups and each group was assigned a level of treatment ( control, 0.5 ppm and 1.0 ppm HgCl₂ ). The performance of the fish in each group placed in the channels was scored. An analysis of data obtained from the migration experiments indicated that sublethal mercurialism had a disruptive influence on migration patterns of Sockeye salmon alevins. The lower level of intoxication produced a downstream drift in both stocks while the fish treated at the higher level of intoxication showed an upstream migrational tendency in both stocks. The effects of sublethal mercurialism on growth were studied using Sockeye, Chum, and Coho salmon fry. The fish received standard daily feedings. The fed fish for each of the species were divided into three treatment groups ( control, 0.5 ppm and 1.0 ppm mercuric chloride ) .Weight data were collected and analyzed using regression analysis and the analysis of covariance. The fed Sockeye and Chum salmon fry showed a significant weight loss (⍺= 0.05 ) in the 0.5 ppm and the 1.0 ppm treatments when compared to their respective controls. There was no significant difference in weight between treatments in the fed Coho salmon experiment. A six week starvation experiment was designed to test if there were any significant differences in weight loss between control fish and fish treated with 0.5 ppm and 1.0 ppm mercuric chloride. Regression analysis and the analysis of covariance did not reveal any statistically significant differences on the rates of weight loss. A flight responce experiment was conducted using Coho salmon prey and predators. Wild and hatchery Coho salmon prey were used with hatchery Coho predators. Three treatment levels of mercuric chloride were administered ( control, 0.5 ppm and 1.0 ppm ), Prey and predators were placed in an experimental laboratory performance channel and, after a timed exposure to each other, scores indicative of flight responce mere obtained. The data was analyzed using the Kolmogorov-Smirnov Large sample : one tailed test. No significant differences in the responces between treatments were noted for the hatchery Coho. The wild Coho prey treated with 0.5 ppm and 1.0 ppm mercuric chloride had a statistically significant differences when compared to their controls. It was noted that as the level of intoxication increased the the level of flight responce decreased. The results of the above experiments indicate that mercurialism has measurable effects on the physiology and psychology of fish at sublethal level. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 64-70). Also available via the World Wide Web.

The genetic relationship of anadromous (sockeye salmon) and non-anadromous (kokanee) Oncorhynchus nerka was examined in conjunction with the breeding behaviour of the two forms to determine: (1) if there is evidence of genetic divergence between the forms where they spawn sympatrically; (2) if such divergence is associated with significant premating isolation between the forms and; (3) if premating isolation results directly from the size difference between the forms (sockeye are much larger than kokanee at maturity). Both sexes exhibit spawning territoriality; females establish and defend particular nest sites until death or displacement, males defend access to specific females from other males until the female has spawned out, they are displaced, or leave to compete for additional mates. Size and prior access to resources (mates and/or specific areas) are significant factors in intrasexual aggression in both sexes, with size the major factor in males and prior access the major factor in females. Females accompanied by males larger than themselves lose weight at a faster rate than those accompanied by males smaller than themselves. Weight loss is related to egg loss, indicating females spawn at a faster rate when accompanied by large males. Male mate preference depends on the size of the male. Males of various sizes prefer females of their own size or larger over females smaller than themselves. In contrast, all sizes of males tested demonstrated no preference between females of their own size and those larger. Large males, which have the widest range of potential mates (because of male intrasexual competition and female choice), are the most selective and small males, which have the narrowest range of potential mates, are the least selective. There were significant differences in allele frequencies between sympatrically spawning sockeye and kokanee. However, there were no consistent differences between sockeye and kokanee at any of five polymorphic loci examined. The extent of genetic differentiation between sympatric forms appears to be less than that between neighbouring populations of the same form, judging from an examination of allele frequencies and/or allele compositions. There was extensive assortative mating by form between sockeye and kokanee, which was not totally accounted for by the large size difference. In the two systems examined, males preferred to mate with females of their own form. In sockeye, such preferences are expected because of the size difference between forms. In kokanee, such preferences are not expected based on size alone, suggesting the evolution of premating isolating mechanisms. The degree of premating isolation was positively correlated with the extent of genetic divergence between sympatric forms. The results of this study are related to existing models of sympatric speciation to hypothesize that sockeye and kokanee have diverged in sympatry. The probable differences in selection between the marine and freshwater environments coupled with the assortative mating resulting from their size difference may have caused subsequent genetic divergence. This divergence appears to have been followed by the evolution of premating isolation. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen viewed (4/7/2008). Includes bibliographical references (leaves 49-56).

Seasonal movements of anadromous brook trout (Salvelinus fontinalis) were studied in riviere au Saumon, James Bay, during 1986 to 1988. A comparison of the biology and energetic parameters between sea run and freshwater brook trout was made in the same system. Anadromous brook trout started their downstream movements in May and displacements peaked in June, but some also occurred in fall. Downstream movements were correlated with spring and fall freshets. Important interannual variation was observed in the movement pattern. Seaward movements of anadromous trout were limited to the brackish waters, as fish congregated at the river mouth. I suggest that movements into brackish waters are passive. Upstream movements began in late July and continued until freezing (November), with the intensity of movement varying annually according to climatic conditions. / Comparison between anadromous and freshwater trout showed very little difference in mean length at age, age at maturity, egg size and fecundity between the two groups. However, examination of energetic parameters indicated that sea run brook trout had a greater increase in condition factor during the summer than the freshwater residents. This raise in condition factor is accompanied by a decrease in water content and a lower water content in the eggs of anadromous fish. These results indicate that benefits associated with anadromous migrations in brook trout reside in the seasonal pattern of energy storage, which is important for the recovery from energy expenditure associated with spawning and overwintering.