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Thesis (Ph. D.)--Columbia University, 1928. / "June, 1928." Vita. Includes bibliographical references (p. 168-170).

This study investigated the differences imposed by the extra set of chromosomes on the immune system of a triploid animal. Various haematological and immunological parameters in diploid and triploid sibling Atlantic salmon (Salmo salar) were compared. Haematocrits were usually the same in diploid and triploid siblings. Erythrocytes and leucocytes were larger and fewer in number in triploid siblings. However, they were not larger or fewer in number by a factor of one third. The proportions of the different leucocyte populations did not differ between diploids and triploids. This was the case for 3 families of diploids and triploids. Non-specific, humoral factors were not consistently different between diploids and triploids. From an investigation of 3 families it was found that there may be family influences on how diploids and triploids compare. A study of the kinetics of responsiveness of non-specific, humoral factors showed that triploids did differ from diploids in the speed of the immune reaction or in the rate of recovery. However, the profile of the differences between diploids and triploids varied between parameters. The rate of increasing agglutinating titres in response to treatment with a commercial vaccine did not differ between diploids and triploids. However, triploids did have a higher average titre after 24 weeks in comparison to diploids. Non-specific, cellular parameters did differ between sibling diploids and triploids. Triploid kidney macrophages had an increased phagocytic capacity but the proportion of phagocytic cells did not differ. Intracellular respiratory burst activity was not different between diploid and triploid kidney macrophages. Diploids and triploids did not respond differently to predator stress and there was no difference in susceptibility to Aeromonas salmonicida ssp. salmonicida challenge. From this study there was no evidence of consistent differences in immmunocompetence or disease susceptibility of diploid or triploid Atlantic salmon.

The aquaculture of Atlantic salmon is a fast-growing industry that has drastically increased over the last decades. Traditionally, diets for Atlantic salmon contained wild sources fishmeal and fish oil but alternatives from plants are increasingly popular substitutes. Although fish do perform well on plant rich diets in terms of growth, carnivorous fish have not evolved to cope with many anti-nutritional factors and other plant derived chemicals. In recent years the importance of intestinal microbes to the health of humans has been established by profiling the microbiota using 16S rRNA as phylogenetic marker in highthroughput sequencing studies and more recently metagenomics profiling. To date, there is sparse information on the teleost intestinal microbiota and the relationship between the microbiota and intestinal health and function. To determine baselines of “healthy” gut microbiota, the gut microbial profiles of fish from freshwater facilities and seawater facilities were analysed. Shared core microbiota were identified, suggesting that certain microbes are actively maintained by the host to fulfil minimum functionality in the gut. Salinity of the environment was identified as important determining factor for the composition of the microbiota. Furthermore, it was found that exposure to plant-based diets including faba bean protein isolates (BPI) induced enteritis in fish fed and resulted in changes of the host transcriptomics including processes related to solute transport, metabolism, tissue integrity and inflammation. The gut microbiota of the fish fed BPI was also found significantly altered and functional analysis suggest an increased genetic potential for sporulation/germination and isoflavonoid biosynthesis. Microbes identified as uniquely present and absent in the fish showing high levels of enteritis across diets could be used as future screening targets to identify onset of enteritis in fish without external signs of sickness.

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I used physiological stress as in indicator of welfare of adult Atlantic salmon during transport onboard a commercial live-haul vessel, the Sterling Carrier under actual operational conditions. This state-of-the-art vessel incorporates both flow-thru (open-hold) and re-circulating (closed-hold) live-hold configurations to safely transport fish under diverse environmental conditions. Measurements of bulk oxygen uptake rates (bulk MO₂) for fish masses ranging from 20 to 40 tons during open-hold transports (n=89) revealed a slightly elevated bulk MO₂ that was comparable to routine bulk MO₂ measured in adult Atlantic salmon, Salmo salar held in large tanks and also to resting MO₂ of individual Pacific salmonids measured in swim-respirometers. These results indicate a low level of stress, and suggest that open-hold live-haul transport aboard the Sterling Carrier does not compromise fish welfare. While closed-hold transport protects fish from poor environments, water quality conditions progressively deteriorate as respiratory CO₂ accumulates in the water. I measured water CO₂ and pH changes during closed-hold transport experiments and used these data to model CO₂ and pH changes over a wide range of transport conditions. Model outputs demonstrated that the partial pressure of CO₂ (Pco₂) could accumulate to potentially deleterious levels (>10 torr) in 20-158 min depending on fish stress levels and loading densities. These data may be useful in estimating transport lengths possible under Pco₂ thresholds, which are presently lacking for live-haul transport. The effects of 3-h and 24-h exposures to elevated water Pco₂ (hypercarbia) on blood pH and post-mortem flesh quality were also measured in adult Atlantic salmon. While elevated water Pco₂ disturbed blood pH as predicted, there were minimal effects on flesh quality based on rigor mortis and flesh pH assessments, which were further reduced if fish were allowed to recover for 24-h after a hypercarbic exposure. This study provides novel insights into a) current techniques of assessing fish welfare during live-haul transport, b) limitations associated with transporting fish under re-circulating conditions, and c) effects of elevated Pco₂ on flesh quality indicators in adult Atlantic salmon. / Science, Faculty of / Zoology, Department of / Graduate

Rates of mortality among young salmon passing through a high speed, model propeller, turbine operating under a 50 ft hydraulic head but under various, draft tube suctions are given. Effects, on both fish mortality and turbine performance, of admission of compressed air into the turbine at various locations to reduce the effect of cavitation (believed to be the major cause of fish mortality in the turbine) are discussed . At low turbine speed and low efficiency, admission of air immediately downstream from the blades reduced the mortality of fish substantially but at high turbine, speed, and high efficiency, the reduction was insignificant. At high turbine speed, the effect, on fish mortality, of admitting compressed air into the penstock and atmospheric air into the turbine draft tube through a 3" diameter steel pipe installed about 1 ft downstream of the blades are shown to be beneficial. Records of biological examination from some of the tests to determine the apparent type of injuries are included. An attempt has been made to correlate the turbine speed with the number of injuries likely to be caused by fish being hit by the blades.The effect of partial vacuum on fish is also given. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate