No description available.

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

Experiments were designed to study the effects of various intensities and durations of light during early development on meristic variation in kokanee and sockeye salmon (Oncorhynchus nerka), pink salmon (O. gorbuscha) and in rainbow trout (Salmo gairdneri). An experiment with sockeye was designed exclusively to test the period of fixation of vertebrae. Among the salmon species rates of hatching and yolk-sac absorption were fastest under the longer light durations and higher intensities. In sockeye and pink an increasing rate of yolk-sac absorption was correlated with increasing amount of light. In trout the rate of yolk-sac absorption showed the opposite results. Mortalities were high under all the experimental conditions. Although meristic variability observed was deemed to be phenotypic yet the affects of selective mortality could not be entirely excluded. Abnormalities in the vertebral column were prevalent in the ‘pre-urostylic' region. The occurrence of abnormal vertebrae was correlated with light only in sockeye. The activities of the pituitary and thyroid glands of trout showed a positive correlation with higher amounts of light. Sockeye scale counts, along the lateral line and on the oblique rows from the origin of dorsal and anal fins to lateral line, were lowest under conditions of higher light and longer durations. Fin ray numbers in all species were the lowest at high light intensities and longer durations. Vertebral counts were lowest at high light intensities and long durations in pink salmon and rainbow trout, but higher in sockeye. At lower light intensities and durations results were variable. Vertebral counts of sockeye increased with increasing light at temperatures of both 8°C and 12°C. Differences among lots at 8°C were significant but those among comparable lots at 12°C were not. The action of light on meristic variability was weak at the higher temperature. It was found in sockeye that vertebral numbers were not fixed before 142 D° and that the period of sensitivity was prolonged (142 D° to 300 D°). / Science, Faculty of / Zoology, Department of / Graduate

The major purpose of this study was to examine the physiological basis of the differences in the early life histories of pink Oncorhynchus gorbuscha, chum O. keta, coho O. kisutch, chinook O. tshawytscha and sockeye O. nerka. To this end, the following working hypotheses were tested: (i) the embryo, alevin and fry of pink and chum salmon are euryhaline, whereas the same life stages of coho, chinook and sockeye are stenohaline and (ii) the euryhalinity of pink and chum is due not to high tissue tolerance but to their ability to regulate the osmotic and ionic concentrations in their blood, whereas the stenohalinity of coho, chinook and sockeye stems from their inability to osmoregulate and ion regulate. The results did not completely support these hypotheses. The LD₅₀ values and the osmoregulatory data obtained from embryos indicated that pink and chum are not euryhaline as hypothesized but like coho, chinook and sockeye embryos are stenohaline. However, pink and chum embryos showed significantly greater salinity resistance and osmoregulatory ability than embryos of the other species. The data obtained from alevins also did not support the working hypothesis for alevins of all five species were found to be stenohaline. But, as in the case for embryos, pink and chum alevins showed greater salinity resistance and osmoregulatory abilities than coho and sockeye alevins. This ability of pink and chum was correlated with better ionic regulation of sodium and chloride. Although chinook alevins survived considerably longer in 31.8 °/oo sea water than coho and sockeye alevins , their ability to osmoregulate and ion regulatewas not very different from that of coho and sockeye alevins. It was concluded, therefore, that the greater salinity resistance of chinook alevins was due to high tissue tolerance. Contrary to the results with embryos and alevins, the data obtained from fry supported the working hypotheses. The results showed that pink and chum were euryhaline and that this condition was due to their ability to osmoregulate and control the levels of sodium and chloride in the blood. Coho, chinook and sockeye fry were found to be stenohaline and were unable to regulate the osmotic and ionic concentrations in their blood. As in the case of alevins, chinook fry, due to higher tissue tolerance, manifested greater salinity resistance than coho and sockeye. When the data for all species of embryos and fry were grouped and compared to the alevins taken as a group, the LD₅₀ values of embryos and fry were found to be significantly greater than those of the alevins . The blood osmotic concentrations of embryos and fry exposed for the same duration in 31.8 °/oo sea water were significantly lower than the blood osmotic concentrations for alevins. It was included, therefore, that embryos and fry have greater salinity resistance than alevins because of the greater osmoregulatory ability of embryos and fry. On the basis of these results as well as information obtained from the literature, speculations were made on the phylogenetic relations within the genus Oncorhynchus. / Science, Faculty of / Zoology, Department of / Graduate

North American Pacific salmon (Oncorhynchus spp.) are heavily exploited in coastal fisheries of the gantlet class (Paulik and Greenough, 1966). The Canadian fishery of Juan de Fuca Strait, British Columbia, is a particularly complex example involving four gear types: gillnet, seine, troll and sport which harvest, at various times, large numbers of all salmon species. Because salmon are highly available to fishing gears, exploitation must be carefully regulated. This study, based on various field data and catch statistics, documents factors affecting exploitation: seasonal timing of exploitable salmon, distribution and amount of fishing gear, relative gear efficiency, accessibility of salmon to the gear, vulnerability of salmon to the gear. All species and gears are covered to varying degrees. Each species has a characteristic seasonal timing, but species vary in run duration and timing consistency between years. There are considerable overlaps in species timing which complicate intraseasonal management. In general sockeye (O. nerka) enter in July and August followed by pink (O. gorbuscha) from mid-August to early September, coho (O. kisutch) in September, and chum (O. keta) in October. Chinook (O. tshawytscha) migrations intermingle with all species. Additionally, chinook and coho are exploited on oceanic migrations. Fishing gears are distributed over ninety linear miles from the Bonilla-Tatoosh net line to Victoria. During the August-October net fishery seines fish within five to ten miles of the net line; gillnets fish offshore, from the net line to Sheringham Point, the eastern commercial boundary. Sports fishermen are clumped near shore, east of Sheringham Point, in close proximity to launching or marina facilities. Gear types showed obvious overall differences in relative gear efficiency, based on catch and effort statistics from two or more gear types operating at the same time in a particular area. For example on coho, one seine equals 265 sport units; one gillnet, 63 sport units; and one troller, 8 sport units. Migrating salmon of all species favoured offshore Canadian waters except near Sooke; all species avoided waters east of Race Rocks where 30 per cent of the sport fleet fishes, the discrepancy was least pronounced for chinook. Based on troll catches using standardized gear, coho favoured surface waters above 27 meters; chinook were most abundant below 36 meters. During periods of spawning migration activity, all species favoured the 18-36 meter depth stratum. Gillnets were directionally size selective for all species, but direction and intensity of selection varied between species and between months within species. Because fleet mesh distribution remains relatively constant each year, changes in fish size will have a pronounced effect on gillnet exploitation. Troll gear was species and size selective; however of importance, subtle fishing techniques have a significant effect on selectivity of lures and may be a serious source of bias in empirical lure studies. Coho decreased in susceptibility to hook and line gear between mid-August and mid-September, apparently due to decreased feeding intensity; this has the effect of lowering hook and line catch success for constant abundance. Future studies on lure selection should stress selective mechanisms rather than empirical description. The complexity of inter seasonal and intraseasonal management strategies applicable to the Juan de Fuca fishery undoubtedly are best studied using techniques of systems analysis. However, present gantlet fishery simulation models (Royce et al., 1963; Paulik and Greenough, 1966, detailed in Greenough, MS 1967), although highly sophisticated, lack sufficient generality for direct application to the Juan de Fuca situation. / Science, Faculty of / Zoology, Department of / Graduate

Triploidy was induced in rainbow trout, Salmo gairdneri Richardson, by heat shock (10 min at 26, 28 or 30°C, applied 1 min after fertilization at 10°C) and in pink salmon, Oncorhynchus gorbuscha Walbaum, and coho salmon, 0. kisutch Walb., by hydrostatic pressure shock (1, 2, 3 or 4 min at 69,000 kPa, applied 15 min after fertilization at 10.5°C). Triploid individuals were identified by the flow cytometric measurement of DNA content of erythrocytes stained with propidium iodide. Gonadosomatic index was reduced to a much greater extent in triploid females than males. Triploid ovaries remained very small, and contained virtually no oocytes. Triploid testes became quite large, but few cells developed beyond the spermatocyte stage. Triploid male rainbow trout had significantly lower spermatocrits than diploids, and their spermatozoa were aneuploid. Growth rates were the same for diploid and triploid rainbow trout, but triploid female pink salmon were smaller than maturing diploid females and diploid and triploid males of the same age. Triploid males of both species developed typical secondary sexual characteristics and had normal endocrine profiles for plasma sex steroids and plasma and pituitary gonadotropin, but their cycle was delayed by about one month. Triploid females developed no secondary sexual characteristics and showed no endocrine signs of maturation, even at the level of the pituitary. Vitellogenin synthesis was induced in immature diploid and triploid coho salmon by the weekly injection of 17β-estradiol. Plasma vitellogenin and pituitary gonadotropin levels were significantly elevated over levels of sham-injected fish, whereas plasma gonadotropin levels were slightly depressed. There was no significant difference between diploids and triploids for any of these results, indicating that normal vitellogenesis is not impaired by triploidy per se. It is concluded that triploids of both sexes are genetically sterile, but that only triploid females do not undergo physiological maturation. Triploid testes develop sufficiently for their steroidogenic cells to become active, which is not the case for triploid ovaries. The occasional cells that pass through the normal meiotic block develop to full maturity in triploid males but not in triploid females, probably due to the absence of the appropriate stimulus to initiate and maintain vitellogenesis. Although triploids of both sexes should make valuable tools for basic research on reproductive physiology, only the females will be useful for practical fish culture to avoid the economically detrimental effects of maturation in fish destined for human consumption. / Science, Faculty of / Zoology, Department of / Graduate

British Columbia's salmon industry is currently one of the province's major sources of income. Its development from a primitive fishery to a highly organized industrial operation has had many phases, one of the most significant occuring in the late 19th and early 20th centuries. In this period several technological developments freed the industry from expensive and unreliable manual labour and laid the basis for the modern industry's organization. This study investigates the innovations made in fishing, packing, and canning machinery and shows how intimately related these developments were to each other. A central point in this thesis is the argument that the industry's development at this time was not due to the introduction of a major invention (the "great man" theory applied to machines) but rather to a series of interlocking, mutually supporting innovations which tended to occur in clusters. Another point is that these innovations were called forth by chronic labour shortages which afflicted the province in its early history. Some space is also given to the effects of technology on the workers and canners of the period. Whenever possible primary source material has been used, including company records, letters and other papers of the early canners, early newspaper and periodical accounts, government reports and regulations of the time, and interviews with pioneers of the fishing industry. Secondary sources have, as much as possible, been restricted to clarification or supplementation of the original material. / Arts, Faculty of / History, Department of / Graduate

Salmonid alphaviruses (SAV) are a group of viruses that have recently emerged as a serious threat to the salmonid aquaculture industry in Europe. Over recent years, diseases caused by SAV have severely hampered the Scottish, Irish and Norwegian Atlantic salmon industry, and are considered to be among the major economically important viral diseases affecting the industry at present. Amongst the six subtypes characterised so far, Salmonid alphavirus 1 (SAV1) causes severe pathology in the heart, pancreas and the skeletal muscle of Atlantic salmon leading to death and growth retardation in the affected fish. The biochemical characteristics of the virus and the sequential pathology of the diseases caused by SAV have been described; however the mechanisms responsible for causing the disease and the host defence mechanisms against the virus are poorly defined. This thesis therefore examined the pathogenesis of SAV infection at the cellular and molecular level in vivo in salmon and in vitro in salmonid cells, with a special emphasis on host immune defence mechanisms against the virus. SAV was first isolated from Chinook salmon embryo-214 (CHSE-214) cells in 1995 in Ireland. Several cell lines have since been used to grow the virus. In the present study, three established salmonid cell lines, Chum salmon heart -1 (CHH-1), CHSE-214 and Salmon head kidney -1 (SHK-1) were evaluated for their ability to support the isolation of SAV-1 from infected fish tissue, with CHH-1 cells giving the fastest cytopathic effect (CPE) during primary isolation. The CPE appeared as localised cell-rounding on CHH-1 and CHSE-214 cells, although in SHK-1 cells, the cells were seen to slough off the monolayer relatively later than with the other two cell lines during the infection. The host response to SAV infection was evaluated by experimentally infecting Atlantic salmon parr using a cell culture-adapted virus isolate. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) was developed to examine the virus load in the fish, from which it was found that the highest viral RNA copy number was detected at 5 day post infection (d.p.i), of the 90 day experimental infection period. Characteristic pathological lesions were only seen in the pancreas and the heart but not in the skeletal muscles of the infected fish. A gene expression study using qRT-PCR revealed the rapid induction of interferon (INF) and INF-associated genes in the head kidney of the infected fish compared to the control fish. The Mx protein was found to be highly expressed in the heart and the mucous membranes of infected fish by immunohistochemistry. Interestingly, the pathological changes that were seen occurred some time after the peak expression of genes associated with the INF-1-pathway. When the host-virus interaction of Atlantic salmon infected with SAV was examined using a microarray, a potent first line defence response was observed, together with the signatures of early activation of the adaptive immune response during the initial stages of the infection. Genes associated with transcription, translation and lipid metabolism were significantly differentially expressed in virus infected fish compared to control fish. A large array of antiviral genes was significantly expressed, amongst which were some of the genes also described in mammalian alphavirus infections. Genes associated with apoptosis and anti-apoptosis were also seen to be differentially regulated showing the complexity of the host-virus interaction. Collectively, all of these findings suggest that a non-specific antiviral immune response takes place providing rapid immune protection during the early stages of SAV infection in salmon. In the study on morphogenesis of SAV in salmonid cells using electron microscopy (EM), a rapid internalization of virus into the cells and generation of replication complexes using the secretory pathway of the cell, similar to mammalian alphavirus replication was observed. The mature viruses were released through surface projections, acquiring envelopes from the host cell membrane. From the ultrastructural studies of the salmonid cells infected with SAV, a progressive chromatin marginalisation and condensation could be seen, leading to cellular fragmentation, forming membrane bound apoptotic bodies, characteristic of progressive apoptosis. The activation of caspase-3 in the cytoplasm and genomic DNA damage were also seen in the infected fish cells, indicating that apoptosis is the main cause of cell death during SAV infection. The results of this study have increased our knowledge and understanding of the cellular and molecular mechanisms involved in the pathogenesis of SAV infection, emphasising the importance of the first line defence mechanisms against SAV infection in salmon. This has given an interesting insight into the host mechanisms used to combat the virus during infection, and will undoubtedly be useful for designing new vaccines and management strategies for prevention and control of this important disease

Stress, including extreme or rapidly changing temperatures, are known to have deleterious effects on fish health and physiology. This thesis examines the combined effects of elevated acclimation temperature and acute handling stress on the number of antibody producing cells, plasma lysozyme concentrations, and the number of pronephric leukocytes in juvenile chinook salmon (Oncorhynchus tshawytscha). An additional goal of this thesis was to explore the effects of a temperature fluctuation, as a potential instigator of thermal shock, on innate immunity in wild fall chinook salmon of the Columbia River, specifically to determine if there are effects on plasma lysozyme concentrations and on the frequencies of lymphocytes, neutrophils, and thrombocytes in circulation. Finally, based on results found in an experiment involving elevated acclimation temperature, the relationship between the number of antibody producing cells and fish body weight was examined. Plasma lysozyme concentrations and the number of pronephric leukocytes were both affected by acclimation to 21��C compared to 13��C. While a positive relationship was found between temperature and lysozyme, an inverse relationship was found between temperature and the number of pronephric leukocytes. Plasma lysozyme concentrations, the number of pronephric leukocytes, and the number of antibody producing cells did not respond to the stressor, and the combination of elevated temperature and stress did not have an additive effect on any of the physiological or immunological variables studied. Differences between controls and temperature-treated fish were not detected among individual time points throughout a temperature fluctuation experiment, despite overall responses in plasma lysozyme concentrations and the frequencies of circulating lymphocytes. The frequencies of circulating neutrophils and thrombocytes did not respond to the thermal stressor. Finally, a significant positive relationship was detected between the number of antibody producing cells (assessed by a hemolytic plaque assay) and body weight among non-stressed fish acclimated to 21��C and 13��C. Regardless of acclimation temperature, these results emphasize the importance of the standardization of fish size for immunological experiments. Results from this thesis suggest that some components of innate immunity are affected by elevated acclimation temperatures and that the adaptive immune system is affected by acclimation temperature differently in small and large fish. / Graduation date: 2001