Carl Schreck

Professor, Fisheries & Wildlife

Office: Nash 170
Phone: (541) 737-1961
Departmental Web Page
Pub Med

Ph.D. 1972, Colorado State University

KEYWORDS: Stress; Reproduction; Hormone Action; Effects of Fitness

My research focus is directed at understanding how the environment and genetics control physiological performance traits of fishes. More specifically, my group studies the endocrinology of stress and reproduction with an emphasis on the steroid hormones; namely, how the activity of the hormones are regulated and determination of the physiological and behavioral effects of the hormones. To this end, we look at hormone concentrations and steroid hormone receptor dynamics. With regard to the corticosteroids, we are interested in learning their role during stress and their effects on metabolism and hydromineral balance, general health including regulation of the immune system and disease resistance, and orientation involving such activities are predator avoidance and migration. We are also interested in effects of stress on developmental processes including juvenile transitions and reproduction. With regard to the sex steroids, our work is directed at two main questions: how sex is determined and how final maturation is controlled. We do this research within the context of knowing that the animals live in a variable natural environment and that different populations of the same species of fish may differ systematically and hence in genetic expression of traits of interest.
While this research aims at providing basic understanding, it is ultimately directed at solving fishery resource concerns. Studies presently include evaluation of Columbia River fishery management programs such as fish passage and transportation facilities. Salmon and trout are evauated from reaches above dams downstream into the ocean; these evaluations include comparisons of wild and hatchery genotypes and "evolutionarily significant units" under the Endangered Species Act. Salmonids are the emphasis of this work, but we have research on other species as well. These include a project on potential endocrine disrupting substances on reproduction of sturgeon and salmon, a study on mechanisms of sex determination in tilapia and development of sex control in this species and salmonids for aquaculture, research in to the area of the stress response of commercially important marine species such as sablefish for harvest regulations, and culturally important sensitive species such as Pacific lamprey.
My group has studies in the field and in the laboratory. Many of the techniques we employ can be categorized as physiological and to some extent ethological. However, for genetic characterization of northwestern salmonids we employ loci identification based on allozymes, mitochondrial and nuclear DNA techniques for classification, and classical morphological analyses as well as assessment of life history traits.