Testosterone was isolated from both the "free" and conjugated steroid fractions obtained from plasma of spawned male and female sockeye salmon. Structure of the steroid was confirmed by several criteria including chemical transformation, a sulphuric acid chromogen and infrared spectra. Conjugation with glucuronic acid was established by use of saccharo-1:4-lactone, an inhibitor for β-glucuronidase. Position through which the conjugation occurs was not established. In other species conjugation is through the 17 β-hydroxy group rather than the theoretically possible 3-enol form in the ∆⁴⁻³ ketone. Testosterone was found in the conjugated but not in the "free" form in testes of migrating 0. nerka. Dehydroepiandrosterone and androsterone, the principal conjugated steroids in normal human plasma were not detected in several plasma samples tested. / Science, Faculty of / Zoology, Department of / Graduate

Supervisor: N. R. Liley The endogenous and exogenous factors contributing to a diel rhythm of locomotor activity in juvenile sockeye salmon Oncorhynchus nerka (Walbaum) were examined in the laboratory. The basic measure employed in the investigation was spontaneous locomotor activity. High frequency sound (800 kHz) was used as a monitoring technique to collect continuous activity records. Three major areas received attention. First, a description and analysis were provided for the entrained diel activity pattern under three different temperatures (5°, 10°, and 15°C) and three different photoperiods (8L 16D, 12L 12D, and 16L 8D). The combined effects of temperature and photoperiod upon the basic 24 hour response were recorded and analyzed. Juvenile sockeye salmon were nocturnally active immediately after emergence from the gravel. A diurnal activity pattern was gradually acquired during the following 14 days and was maintained for 12 months. Photoperiod was the primary environmental synchronizer for either diurnal or nocturnal activity. The endogenous component of the activity rhythm was examined in constant environmental conditions. Constant light (34.4 lux at 10°C) facilitated the free-running response while constant dark inhibited it. The spontaneous frequency in constant light was 23.30 hours but this could be altered by light intensity or periodic feeding. The final experiments focused upon the relationship between the environmental stimulus (photoperiod) and the physiological sensory mechanisms mediating the entrained response. The eyes were the primary photoreceptors mediating information about the light-dark environment. The entrained activity response disappeared when the retina was not illuminated. When the pineal body was removed or shaded, juvenile sockeye responded with increased activity. Intraperitoneal injections of melatonin (N-acetyl-5-hydroxy-tryptamine) or serotonin (5-hydroxy-tryptamine) selectively altered the activity amplitude in either the light or dark respectively. Juvenile sockeye salmon possess an endogenous circadian activity rhythm which is synchronized by the photoperiodic cycle. The fish are generally light active, except for the period immediately after emergence. However, interactions between daylength and temperature can result in temporary dark active responses. Mediation of the photoperiodic information occurs via the retina, but without transmission by optic nerve pathways. Chemical agents (melatonin and serotonin) produced by the retina and/or pineal might control the activity amplitude in light and dark, thus resulting in the characteristic entrained pattern. / Science, Faculty of / Zoology, Department of / Graduate

The sockeye and kokanee are, respectively, the anadromous and non-anadromous forms of the Pacific salmon species, Oncorhynchus nerka. Both life history types inhabit Babine Lake, British Columbia, a tributary of the Skeena River system. The purpose of this study was to examine the ecology, morphology and behaviour of sockeye and kokanee in the hope that an understanding of these would provide clues to the genetic relationship of the two forms in Babine Lake. A comparison of the life histories of sockeye and kokanee at Babine Lake revealed a.number of differences. At the time they undertake their seaward migration (usually during the spring of their second summer) sockeye smolts have a mean length greater than that of same-age kokanee. Smolts have an approximately equal sex ratio while, among kokanee, males usually exceed females in abundance. As a result of better growth conditions in the ocean, sockeye, at maturity, are much larger than kokanee. Related to this basic difference in size are differences in fecundity, egg size and testis weight in each of which sockeye exceed kokanee. Laboratory experiments revealed that, regardless of the male parent, progeny of the larger sockeye eggs had an initial size advantage over the progeny of kokanee eggs which they maintained through July of their first year. There was no conclusive evidence of differential mortality to hybrid embryos. There are differences between sockeye and kokanee in two meristic characters: number of lateral line scales and number of vertebrae.In both instances, mean values for sockeye exceed those for kokanee. It is suggested that this difference may not be genetic in origin but rather the result of differences in the amount of yolk incorporated in eggs. The two forms did not differ in gill-raker count. Electrophoretic examination of haemoglobins and muscle myogens revealed no differences between Babine Lake sockeye and kokanee. A detailed examination of the reproductive behaviour of sockeye and kokanee revealed that they spawn sympatrically in a group of streams known as the "early streams." These are small streams which experience considerable fluctuation in water levels and spawning suitability from year to year. Sockeye and kokanee in the early streams overlap almost completely in their spawning season and in their distribution on the spawning grounds. Evidence is presented that hybridization does occur under natural conditions. A study of the homing performance of mature sockeye and kokanee displaced from early streams indicates that they are less likely to home than are sockeye displaced from Pinkut Creek, a large, stable stream in the same area. It is suggested that a reduced homing tendency might be an adaptation to the unstable nature of the early streams. Fish homing to an early stream to which access is blocked, either by low water or by an obstruction, have the alternative of entering other, nearby streams of similar type. The hypothesis which most readily encompasses the available information is that the sockeye and kokanee in the early streams at Babine Lake are part of the same polymorphic population. This polymorphism is presumably maintained by a balance of contending advantages and disadvantages. Kokanee suffer the major disadvantage of smaller size resulting in reduced fecundity, smaller egg size and, probably, reduced spawning success. However, it would appear that they persist in the early streams because they are able to utilize spawning grounds which are unavailable to sockeye under low water conditions. The existence of such a sockeye/kokanee polymorphism and the reduced tendency to home are both thought to be genetically regulated adaptations which enable the early stream populations of O. nerka to maximize their utilization of the available spawning grounds in. the face of extreme fluctuations in the suitability of spawning streams. The hereditary mechanism which would regulate such a sockeye/kokanee polymorphism is not known. Possibly a super-gene is involved. Whatever the mechanism, it would appear that factors other than genotype can influence the tendency to smolt: females are more likely to smolt than males; larger and/or faster growing fish are more likely to smolt than smaller, slower growing fish; immature fish are more likely to smolt than those in which maturation processes have already begun. The applicability of the polymorphism hypothesis to sockeye and kokanee populations in other areas is discussed. / Science, Faculty of / Zoology, Department of / Graduate

Proefschrift--Leyden. / "Stellingen" [1] page inserted. Summary in German. Vita. Bibliography: p. 186-193.

The pineal organ in sockeye salmon and its relation with other epithalamic components has been studied. Histological and histochemlcal methods were used and the influence of experimental photoperiods on the histology and secretion in the juvenile pineals investigated. Photosensory and supporting ependymal cells have been identified. Lipofuchsin and melanin are absent in the pineal epithelium. Besides sensory fibres, efferent end-loops are present on the sensory and supporting cells. The dorsal pineal nerve tract is probably of a mixed type. Although the blood supply is profuse an endocrine or neuroendocrine activity is not indicated. It is proposed that the pineal organ in both juveniles and adults is photosensory and secretory. The apocrine secretory activity of the sensory and some supporting cells is probably associated with either the maintenance of constant chemical composition of the cerebrospinal fluid or supply of certain substances to the nervous tissue. The subcommissural organ is metabolically more active than the pineal. The secretion consists of glycogen, mucopolysaccharides, mucoproteins, glycoproteins and aldehyde-fuchsin positive granules. Chrome-alum positive granules are abundant in the subcommissural organ. Both the pineal organ and the subcommissural organ appear independent of light's influence on secretion and histology. It seems more plausible that apocrine secretory activity is controlled by some internal factors. It is suggested that the pineal organ might be of some advantage in the light dependent behaviour of this species in terms of intensity detection. Future work is necessary in this direction. / Science, Faculty of / Zoology, Department of / Graduate

Conditioning experiments demonstrated a significant, repeatable and reversable capacity for groups of yearling sockeye salmon (Oncorhvnchus nerka) to discriminate between perpendicular planes of linearly polarized light. Polarized light was also shown to influence orientation behavior when compared with orientation under unpolarized light. A limited number of fish orientated at a common angle (between 22.5 and 45 to the right of) with respect to the plane of polarization. Possible analysers of polarized light are discussed. / Science, Faculty of / Zoology, Department of / Graduate

The possible role of prolactin in the freshwater osmoregulation of laboratory reared juvenile chum (Oncorhynchus keta) and sockeye (0. nerka) salmon was investigated. Pituitary cytology indicated that prolactin cells of both species develop gradually during freshwater residence and downstream migration. During this time the prolactin cells increase slightly in size; the number of prolactin cell follicles also increases. Simultaneously, the intensity of cytoplasmic staining with erythrosin increases. Alternate day injections of 5 or 15 μg/g body wt prolactin (ovine) did not affect survival of chum fry in deionized water. Thirty micrograms per gram slightly increased survival while 60 μg/g decreased survival in deionized water. Prolactin injections prolonged, to a small extent, the survival of sockeye smolts in deionized water. Sockeye fry suffered only slight mortality after transfer from fresh water to deionized water. A prolactin dose of 5 μg/g did not alter this survival; however, doses of 15 μg/g or higher resulted in 40 to 70% mortality after 10 days in deionized water. Alternate day injections of 10 μg/g prolactin had no effect on plasma sodium concentrations of chum fry, sockeye fry, or sockeye smolts after transfer from sea water to either fresh water or deionized water. It is concluded, from histological and physiological evidence, that prolactin does not play an obvious role in the freshwater osmoregulation of juvenile chum and sockeye salmon. The possible role of prolactin in the spawning migration of adults is discussed. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 1993. / Vita. Includes bibliographical references (leaves [134]-148).

The influence of temperature and activity on certain cardiovascular and respiratory parameters in adult sockeye salmon was studied. Cannulae were implanted in the dorsal aorta and buccal cavities of fish which were forced to swim in a tunnel-type respirometer until they fatigued. Three groups of fish were acclimated and tested at 5, 15, and 22°C respectively. Pressures recorded from the dorsal aorta and buccal cavity gave information about heart rate, blood pressure, pulse pressure, ventilation rate and pressures in the buccal cavity before, during and after the fish were fatigued by swimming. Hematocrit data revealed the blood oxygen capacity of these fish, to be approximately 9 vols %. Knowledge of the blood oxygen capacity, heart rate and the metabolic rates of adult sockeye at various temperatures and levels of activity allowed calculation of stroke volume and cardiac output by the Fick principle. During successively greater swimming activity heart rate and blood pressure rose in all three test groups while ventilation rate was highly variable. Calculated stroke volume and cardiac output increased markedly and it is suggested that the peripheral resistance of the vascular system diminished during exercise. The increase in heart rate during exercise is thought to be related to a release of vagal tone or possibly, to the presence of circulating catecholamines. Elevated dorsal aortic pressure during activity was undoubtably the result of elevated cardiac output. Since dorsal aortic pressure did not increase in accordance with the increases in oxygen uptake observed during activity it is suggested that peripheral resistance decreases in the face of elevated cardiac output. Post-exercise ventilation rate approached resting levels within one hour after fatigue but heart rate and buccal pressure remained above resting levels. High post-exercise heart rates and buccal pressures were believed to be evidence for the presence of an oxygen debt. Blood pressures fell below resting levels in the 15 and 22°C test groups following fatigue and remained low one hour after fatigue. These low pressures may indicate that vasodilation of peripheral vessels had occurred to facilitate flushing of the muscles with blood and aid in the elimination of oxygen debt. Temperature appeared to directly influence heart rate of both quiescent and active fish. Higher acclimation and test temperatures produced higher heart rates than lower acclimation and test temperatures. Presumably temperature influences heart rate by acting directly on membrane phenomena in the myocardium. No cardiac failure was observed in sockeye, even at 22°C during severe exercise. Routine and active oxygen uptake increased with temperature but the rate of increase of active oxygen uptake decreased with temperature - possibly because of the low availability of oxygen in warm water. Temperature appeared to directly influence the ventilation rate of quiescent fish. Higher temperatures were accompanied by high ventilation rates, undoubtably as a result of increased routine metabolic rate at high temperatures and scarcity of oxygen in warm water. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M. Sc.)--York University, 2000. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 233-246). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ59547.