Coho underyearlings settle toward the bottom when illumination decreases. The critical intensity for this response was found to be approximately 1 foot candle. A study of the nipping phenomenon in coho and kamloops trout revealed that coho nip more Intensively than trout in a homotypic group. However; in a heterotypic group of equal numbers, trout nip more readily. In a heterotypic group coho nip less frequently and show a preference to nip other coho. By comparison, the nipping Intensity of trout is not reduced and they nip either species equally. Factors affecting nipping are size, color and light intensity. In a group of coho or trout, there is a marked tendency for the larger members to nip the smaller. Red and orange colors are least effective in eliciting a nipping response. Light intensity changes between 4- and 12 foot candles have no significant effect; however, below k foot candles nipping declines rapidly as illumination is decreased. The social releaser for nipping is movement but size and color are important components of the releaser. Additional patterns of behavior have been described for trout, namely, "threatening" and fighting. / Science, Faculty of / Zoology, Department of / Graduate

Studies were conducted to determine the onto genetic changes in the number and relative concentration of the electrophoretically distinguishable hemoglobin polymorphs of coho salmon, Oncorhynchus kisutoh and the influence of certain environmental factors upon the expression of the hemoglobin variants. In addition some of the oxygen equilibrium characteristics of the hemoglobin of freshwater fry and adult coho were investigated using both hemolyzates and whole blood. Throughout the life cycle of coho salmon seventeen to nineteen distinct hemoglobin components were identified in micro-starch-gel electropherograms prepared in borate buffer at pH 8.5. These components formed three main electrophoretic hemoglobin patterns associated with different stages of the life cycle. Unhatched embryos and alevins possessed twelve anodic and one cathodic components. All except three anodic components had disappeared from the blood of free-swimming fry fourteen weeks after hatching. This three-component pattern was retained until the beginning of the presmolt period, approximately eleven months after hatching. At this stage, five new cathodic components, one new anodic component and one anodic component which had previously been visible in alevin electropherograms appeared. In presmolts and smolts these additional seven components accounted for less than 20 % of the total hemoglobin of the blood while the three components observed in fry blood accounted for the remainder. Following migration to sea water the relative concentration of these seven components gradually increased to 45 to 50% of the hemoglobin over a two-month period. No further change in either the number or relative concentrations of the hemoglobin components was observed during the remaining phases of the life cycle. Since it was apparent that changes in hemoglobin pattern were temporally associated with changes in the characteristics of the environment occupied by the juvenile coho the effects of water temperature, dissolved oxygen concentration and salinity upon the physical development and electro-phoretic hemoglobin pattern of underyearling coho were examined. Exposure to freshwater temperatures of 1.4 to 15.0 C, dissolved oxygen concentrations of 2.2 to 9.7 ppm and salinities of 0 to 30 °/oo for periods of 49 to 60 days had no influence upon the electrophoretic hemoglobin pattern of either 3 1/2-month-old fry or 11-month-old presmolts. Presmolts reared for 60 days in freshwater at 15 C and in 10 °/oo salinity at 9.2 C grew at a highly accelerated rate and were equal or greater in size than 16 1/2-month-old postsmolts which had been residing in sea water for one month. These large presmolts retained the hemoglobin pattern characteristic of normal presmolts of the same age. Postsmolts maintained in aerated freshwater rather than sea water underwent changes in the electrophoretic hemoglobin pattern characteristic of sea-water residents. The foregoing observations suggest that age rather than physical size or environmental factors is the main determinant in the expression of the polymorphic hemoglobins of coho salmon. The oxygen equilibrium characteristics of adult coho hemoglobin and hemoglobin components A6-8 (fry hemoglobin) isolated from adult hemolyzates by ion-exchange chromatography were investigated. Adenosine triphosphate concentrations ranging from 0.0 to 0.76 moles/mole hemoglobin had no influence upon the oxygen equilibrium of adult hemolyzates whereas at a concentration of 7.56 moles/mole P₅₀ increased by 1 to 2 mm Hg. Since erythrocyte ATP concentrations of freshwater adult coho ranged between 0.8 and 1.3 moles/mole hemoglobin this organic phosphate is probably not a modifier of oxygen affinity in coho salmon. The hemoglobin of adult coho was relatively insensitive to variations in pH and temperature with ∅ =-0.172 at 9.8 C over the pH range of 6.95 to 8.20 and Δ log P₅₀ = 0.019 between 5 and 15 C. The Bohr effect of fry hemoglobin was nonlinear so that ∅ = -0.033, -1.729 and -0.182 in the pH ranges of 6.82 to 7.08, 7.08 to 7.50 and 7.50 to 8.50, respectively. The estimate of Δ log P₅₀ was 0.056 for fry hemoglobin. Thus at 9.8 C the oxygen affinity of fry hemoglobin exceeded that of adult hemoglobin at pH greater than 7.3 but was lower at values of pH less than 7.3. At pH 7.4, the P₅₀ of fry and adult coho hemoglobin was 8.4 and 17.9, respectively. In neither case was a Root effect observed. Heme-heme interaction was similar for both adult and fry hemoglobin and the value of n always exceeded 1.0. The estimate of n was generally less than 2.0 at pH greater than 7.0 and tended to decrease as the pH or the equilibration temperature increased. Studies with fry and adult whole blood equilibrated With 0.2 and 3.4 mm Hg of carbon dioxide generally confirmed the qualitative differences observed between the oxygen equilibria of fry and adult hemolyzates. The estimates of P₅₀ at 9.3 C and PCO₂ of 0.2 and 3.4 mm Hg were 5.5 and 12.5 mm Hg respectively for fry blood and 10.7 and 15.6 mm Hg, respectively, for the blood of freshwater adults. / Science, Faculty of / Zoology, Department of / Graduate

Juvenile, pre-smolt coho salmon were subjected to a decrease in environmental temperature from 12°C (temperature of acclimation) to 2°C over a period of approximately 72 hours. During this time, plasma Cortisol values were estimated by the competitive protein binding (CPB) technique. In addition, an histometric analysis of the interrenal tissues of these fishes was performed as a measure of interregnal activity. Experimental results indicated that fluctuations in plasma Cortisol concentrations occurred within 120 hours of the initiation of temperature alteration. Control levels for plasma Cortisol were 2.9 ± 0.75 ug cortiso1/100 ml plasma (mean ±S.D.). Maximum plasma Cortisol concentration, observed at hour 84 after temperature alteration, was 27.0 ± 2.8 ug cortisol/100 ml plasma (mean ± S.E.). By hour 96 experimental cortisol values returned to a level just slightly above those of controls and did not change significantly after that time. Measurements of interrenal nuclear diameters showed a significant increase in interrenal activity 14 days after initiation of exposure to cold. This level of interrenal activity was maintained until the experiment was terminated (20 days exposure to cold). It is concluded from this study that during acclimation to cold temperature, plasma cortisol values of juvenile, pre-smolt coho salmon demonstrate an early and rapid increase (within 120 hours exposure to colder temperature) followed by an equally rapid decrease to a level just slightly above that of controls. Furthermore, it is concluded that juvenile, pre-smolt coho salmon treated in this manner show no histologically demonstrable increase in interrenal activity until well after plasma cortisol values have become stabilized at a level slightly above that of controls (14 days exposure to cold). / Science, Faculty of / Zoology, Department of / Graduate

Some of the kinetic characteristics of the sodium and potassium-activated adenosine triphosphatase of the fragmented cell membranes of cells from the gills of sea water adapted coho salmon Oncorhynchus kisutch, and changes in this enzyme upon exposure to sea water and during the fry to smolt stages of fresh water reared juvenile coho were investigated. Inhibition with 4 X 10⁻⁴ moles/liter ouabain was used to assay the activity of this enzyme since this ATPase is specifically inhibited by ouabain (Skou, 1957). The following assay conditions were found to result in maximal hydrolysis of ATP in enzyme preparations from sea water adapted coho: pH, 7.4; incubation temperature, 40°C; NaCl and KCl concentrations of 100.0 and 20.0 mmoles/liter, respectively, and Mg²⁺ -ATP, 5.0 mmoles/liter. The Km for ATP was 0.2 mmoles/liter. The enzyme activity recorded with magnesium ions as the only cation present (Mg²⁺-ATPase) was not affected by any concentration of ouabain, although the addition of sodium ions (100 mmoles/liter) appeared to inhibit this activity slightly. The additional hydrolysis of ATP observed when sodium, potassium and magnesium ions were present was inhibited by ouabain. The Ki for ouabain was; 7 X 10⁻⁶ moles/liter when sodium and potassium ion concentrations were 100.0 and 20.0 mmoles liter, respectively. The (Na⁺ + K⁺)- activated ATPase of sea water adapted coho was characterized by its high ouabain-sensitive activity and the large activating effect of potassium ions in the presence of magnesium and sodium ions compared to the activity observed with the latter two ions alone. This enzyme in preparations from the gills of fresh water reared fish was characterized by a high activating effect of sodium ions when present with magnesium ions. This sodium activation often comprised over 60% of the total ouabain-sensitive activity. Considerable increases in the total activity, and activating effects of potassium ions and decreases in the activating effects of sodium ions alone were observed when fresh water reared coho were transferred directly to sea water. The changes in the activating effect of the ions were noticable after 5 days exposure to sea water although no changes in the total activity of the enzyme occurred until after 10 days exposure. On a seasonal basis changes in enzyme activity occurred which were apparently linked to the stage of development of the parr-smolt transformation in fresh water reared juvenile coho. Activities during the period of October 1, 1968 to late November, 1968 were generally quite low. A sharp peak in activity occurred in December, 1968 to late January, 1969 which decreased to a low level by mid-February. Up to and including this last period the activity of enzymes from the gills of both fresh water and sea water reared coho were qualitatively similar although the seawater fish always had a higher enzyme activity. During the period of mid-February to late April,1969 the enzyme from fresh water reared coho changed in total activity and characteristics of sodium activation and potassium activation and became very similar to that of sea water reared fish of the same age. / Science, Faculty of / Zoology, Department of / Graduate

The activity of the pituitary-interrenal axis in juvenile coho salmon (Oncorhynchus kisutch) and the relationship of this activity to the numbers of circulating leucocytes has been studied, using histological and histometric techniques. To this end, the effects of injections of mammalian ACTH, of Cortisol acetate and of dexamethasone on the interrenal tissue, on the epsilon cells in the pituitary gland, and on the differential leucocyte counts were investigated. In addition, the activity of the pituitary-interrenal axis and the related changes in leucocyte counts were determined throughout their year of stream residence. Further, the response of this axis, along with corresponding hematological changes to environmental alterations in the laboratory, were studied. Injections of ACTH resulted in a dosage-related stimulation of the interrenal tissue of coho salmon fry. On the other hand, injections of Cortisol acetate and of dexamethasone produced a marked atrophy of the interrenal tissue. All dosages of either ACTH or Cortisol acetate decreased the mean nuclear diameters of epsilon cells, and resulted in their degranulation. In addition, a decrease in numbers of circulating small lymphocytes and thrombocytes resulted from administration of all dosages of ACTH, Cortisol acetate or dexamethasone. It is proposed that the interrenal tissue of coho fry is capable of marked variations in activity, that this tissue is under pituitary control, and that a negative-feedback mechanism operates between the interrenal and the pituitary gland. Additionally, changes in pituitary-adrenocortical activity are reflected in characteristic alterations in numbers of certain circulating leucocytes. The pituitary-interrenal axis of juvenile coho salmon in their natural habitat is inactive, from the time of emergence in spring, and through summer and early fall, compared with the winter and spring samples of yearling coho. In addition, numbers of circulating small lymphocytes were decreased in the winter and spring samples of yearling coho compared with summer and autumn samples. It is suggested that the increased activity of the pituitary-interrenal axis along with changes in leucocyte counts observed in the winter sample of juvenile coho salmon are related to cold-temperature acclimation. Furthermore, it is proposed that the increased pituitary-adrenocortical activity noted in the latest of the three spring samples of yearling coho salmon is associated with the transformation from parr to smolt. The interrenal tissue of juvenile coho salmon maintained in continuous darkness, or exposed to a continuously flashing light for varying numbers of days, was generally more active than that of corresponding control fish subjected to a twelve hour photoperiod. Additionally, small-lymphocyte and thrombocyte counts for darkness-maintained and flash-exposed fish were lower than values for corresponding control samples. On the other hand, no consistent differences in activity of the interrenal tissue were found when fish maintained in continuous light for varying numbers of days and corresponding control fish were compared. It was observed that the pituitary-interrenal axis of juvenile coho salmon was initially stimulated following transfer of the fish from holding tanks to an altered environment. In addition, the activity of the interrenal tissue was increased by exposure of these fish to cold water temperatures; this increased interrenal activity was accompanied by a lymphopenia. It is suggested that the pituitary-interrenal axis of juvenile coho salmon is involved in cold-temperature acclimation. It is concluded that the pituitary-interrenal axis of juvenile coho salmon undergoes marked fluctuations in activity as a result of environmental alterations within the laboratory. Furthermore, an increase in pituitary-adrenocortical activity during acclimatization is characteristically reflected in a decrease in number of.circulating small lymphocytes. / Science, Faculty of / Zoology, Department of / Graduate

Juvenile coho salmon (101-400 mm) were sampled by purse seine off the Pacific Coast from Waatch Point, Washington to Four Mile Creek, Oregon, out to 30 mi offshore, during the months of May, June, and September in 1982 and 1983. Sea surface temperature, surface salinity, surface chlorophyll-a concentration, and Secchi depth were measured at each station. Sea surface temperatures were higher in 1983 than in 1982, while surface chlorophyll-a concentrations and surface salinities were lower. Catch data were not highly correlated with any of the four physical parameters measured. Strong northerly winds and strong upwelling tended to disperse juvenile coho offshore and south. Fish were found closer inshore during periods of weak winds and weak upwelling. In both years the center of distribution of the fish appeared to shift northward as the summer progressed. Larger fish, in general, were found farther north and offshore throughout the year. / Graduation date: 1985

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [169]-179).

Graduation date: 1991

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