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1
Fast, Mark D. "Comparative susceptibilities of salmonids to Lepeophtheirus salmonis infections, biochemical and physiological studies". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63257.pdf.
Testo completo
2
Dawson, Leigh Helen Jane. "Physiological, behavioural and pathological effects of sea lice, Lepeophtheirus salmonis (Krøyer, 1837), on Salmonids". Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU483280.
Testo completoAbstract (sommario):
This thesis examined the physiological, behavioural and pathological effects of sea lice, Lepeophtheirus salmonis (Krøyer, 1837), on wild sea trout, Salmo trutta L., and experimentally infected sea trout and Atlantic salmon, Salmo salar L. to determine how, and to what extent, sea lice cause mortality of their infected hosts. A feeding hierarchy was established in groups of sea lice infected and uninfected Atlantic salmon as a physiological stressor. Results indicated that chalimus did not stimulate physiological changes leading to marine mortality and the intensity of the sea lice infection on a fish was independent of that individual's food consumption. However, preadult stages caused appetite suppression, severe skin lesions and changes in the blood biochemistry of the fish with subsequent recovery to the levels of uninfected fish as the parasite moulted through to the adult stages of the lifecycle. The effects of sea lice on sea trout at either 2 or 6 weeks after sea water transfer were assessed. Both infection intensity and developmental rate were not significantly different between the groups, but a trend of fewer lice on the fish infected 6 weeks after sea water transfer was recorded. Fewer of the fish infected 2 weeks after sea water transfer had resumed feeding by the end of the experiment, leading to a loss of body condition, and suffered more severe damage to the skin and detrimental changes in the physiological integrity as a consequence of feeding preadult lice. The mortal impact of sea lice infection was significantly enhanced in the fish infected 2 weeks after sea water transfer. The findings from this thesis have shown that preadult sea lice can cause mortality of wild and experimentally infected sea trout and Atlantic salmon, particularly if infected at the time of sea water transfer, but under certain conditions sea lice infected hosts can recover from the detrimental effects of both chalimus and mobile stages.
3
Turenne, Eric D. "Lipid Mobilization In Exercising Salmonids". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37075.
Testo completoAbstract (sommario):
Animals rely on lipids as a major fuel for endurance exercise because they pack more joules per gram than any other fuel. However, in contrast to mammals, information on how the mobilization of lipids from endogenous stores is managed to meet the needs of energy metabolism in swimming fish is sparse. Information on in vivo rates of lipid mobilization in swimming fish has been limited to relatively low exercise intensities and has only been investigated in a single species. Therefore, the goal of my thesis was to address this paucity of information by quantifying lipolytic rate in rainbow trout during graded exercise and fatty acid mobilization in Atlantic salmon during prolonged endurance exercise.
In the first part of my work, I hypothesized that like mammals, rainbow trout stimulate lipolysis above resting levels to a peak with increasing work intensity, but subsequently lower its rate at high intensities when ATP production from carbohydrates becomes dominant. To test this hypothesis, I measured the rate of appearance of glycerol (Ra glycerol) in the blood (resulting from the breakdown of triacylglycerol (TAG)) of trout at rest (control) and during graded exercise from rest to Ucrit. Results showed that Ra glycerol in trout averaged 1.24 ± 0.10 µmol kg -1 min-1 and that this rate was unaffected by exercise of any intensity. These experiments revealed that rainbow trout do not modulate lipolysis during exercise. Furthermore, I calculated that baseline lipolytic rate was much higher in trout than in mammals and that this rate is in constant excess of the requirements of energy metabolism.
My second investigation focused on measuring fatty acid mobilization in Atlantic salmon. To date, the majority of studies on energy metabolism in salmonids have used rainbow trout as the ubiquitous model for salmonids. I postulated that domesticated rainbow trout may be far less impressive athletes than their wild anadromous form and other salmonids. In this regard, I proposed that studying energy metabolism in Atlantic salmon (even those from aquaculture) may help to deepen our understanding of the physiology of true long-distance migrant fish. To study the effects of prolonged endurance exercise on the mobilization of fatty acids from endogenous stores in these fish, I monitored the rate of appearance of fatty acids (Ra NEFA calculated from Ra Palmitate) in the blood during 72 hours of sustained swimming. I found that contrary to what has been previously described in rainbow trout, Ra Palmitate (and by proxy, Ra NEFA) is reduced by approximately 64% (from 0.75 ± 0.12 µmol kg-1min-1 to 0.27 ± 0.06 µmol kg-1min-1 and from 19.3 ± 7.8 µmol kg-1min-1 to 6.9 ± 2.0 µmol kg-1min-1 for Ra Palmitate and Ra NEFA, respectively) during prolonged endurance exercise in Atlantic salmon. However, like in trout, even this reduced rate of fatty acid mobilization exceeds the requirements of energy metabolism at rest and during swimming. While further experiments will be necessary, I speculated that this reduction in Ra NEFA may be caused by a partial inhibition of lipolysis to reduce the energetic cost of TAG:FA cycling and optimize fuel budgets during prolonged endurance exercise.
This thesis provides the first in vivo measurements of lipolysis during graded exercise in salmonids and the first in vivo measurements of fatty acid mobilization in Atlantic salmon. From the results mentioned above, I concluded that salmonids mobilize lipids in constant excess of the requirements for energy metabolism, possibly to allow for rapid reorganization of membrane phospholipids in response to changing environmental conditions. However, more anadromous and migratory phenotypes may rely on a tighter control of lipolysis to minimize the costs of substrate cycling and conserve energy on limited fuel stores.
4
Crooks, Lucy Elizabeth. "Organic contaminants in salmonid spawning grounds : occurrences and effects on the early life stages of salmonids". Thesis, University of Portsmouth, 2011. https://researchportal.port.ac.uk/portal/en/theses/organic-contaminants-in-salmonid-spawning-grounds(1b72081d-8873-4f43-a6a6-7388458ec67a).html.
Testo completoAbstract (sommario):
The factors regulating salmonid populations remain poorly understood, although contamination of the freshwater environment has been implicated as a causative factor. Depletion of stocks has become an increasing concern and it is believed that the early life stages are potentially the most vulnerable. Reduction in salmonid stocks has been reportedly linked to water quality and this current study has shown that freshwater pollution can affect the survival and development of salmonids. Environmental concentrations measured in this study varied greatly and high levels of sediment-bound contaminants were found, especially polycyclic aromatic hydrocarbons. Concentrations of waterborne contaminants were similar to levels previously measured, with some high level peaks in triazine metabolites. Field studies, as previous literature has suggested, found a higher mortality in river sites of greater sediment and nutrient loading and in sites with a greater proportion of fine sediment (<63μm). The River Avon was found to have a higher concentration of fine sediment and mortality of implanted eggs in this site was significantly higher than in the Rivers Wylye and Nadder. Although mortality of eggs implanted in river field sites was generally high, few morphometrics and biochemical effects were observed. Laboratory studies examined the toxicity of environmentally relevant levels of water-borne and sediment-bound contaminants on the brown trout (Salmo trutta) but found few acute effects and no specific trends were observed. The results did reveal a higher frequency of yolk sac oedemas for contaminant-exposed alevins in the laboratory trials compared to the control groups. In general survival was high for both the eyed egg and alevin stages when exposed to the water-borne contaminants. However, survival was greatly reduced when the water-borne contaminant exposures were carried out from the fertilisation stage compared to the eyed stage. Generally, sedimentbound contaminants had a greater effect on survival at the egg stage and mortalities were found to be reduced at the fry stage. Additionally, the results from the comet assays revealed that exposure to sediment-bound organochlorine pesticides and polycyclic aromatic hydrocarbons did induce significant acute effects in the form of DNA damage when compared to the control. Such results could indicate that certain pollutants may be problematic for the species at later stages of their development and on into adulthood. In general the findings of this research proved largely inconclusive in terms of specific impacts of contaminants on the early developmental stages of Atlantic salmon and brown trout. The results of these studies did show that the presence of common pollutants within the freshwater environment can have impacts on the survival and development of salmonids. These impacts may have serious implications throughout the lifecycle and could impact heavily on recruitment and survival at both the juvenile and adult life stages, potentially leading to a reduction of wild populations.
5
Lahti, Katriina. "Integrated analysis of aggression in salmonids". Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/lahti/.
Testo completo
6
Höjesjö, Johan. "Behavioural tactics and domestication effects in salmonids /". Göteborg : Département de zoologie, Université de Göteborg, 2002. http://catalogue.bnf.fr/ark:/12148/cb399304702.
Testo completo
7
Benfey, Tillmann J. "The reproductive physiology of triploid Pacific salmonids". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28621.
Testo completoAbstract (sommario):
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
8
Marsden, Matthew J. "In vitro correlates of disease resistance in salmonids". Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU603177.
Testo completoAbstract (sommario):
A variety of nonspecific humoral and cellular immune-parameters were investigated in several families of farmed Atlantic salmon, Salmo salar, known to exhibit differential susceptibilities to Aeromonas salmonicida (furunculosis) in the field (fishfarm) situation. Nonspecific phagocyte functions, respiratory burst activity and leucocyte migration, were not found to be selected for in resistant families. However, nonspecific humoral factors, complement, a2-macroglobulin (aa2m) and non-a2m-antiprotease activity were found to be selected for, with resistant families possessing higher activities during challenge situations. Thus, both complement and antiprotease activity (particularly a2-macroglobulin) are regarded as potential resistance markers against furunculosis. The manner in which these factors affect the disease course of furunculosis are discussed. Antigen specific cytokine assays were developed in response to A. salmonicida antigens following vaccination against this pathogen. Antigen specific proliferation and macrophage- activating factor (MAF) production were demonstrated against A. salmonicida antigens. The potential ability to screen for differential antigen specific responsiveness as a way to assess one facet of the contributions of vaccine design and selective breeding to disease resistance were investigated. Both vaccine formulation and family origin of salmonids were found to influence in the induction and magnitude of antigen specific responses. Reasons for the observed results are discussed.
9
Bailey, Jason. "Energy requirements and feeding behaviour of salmonids in culture /". Umeå : Dept. of Aquaculture, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s264.pdf.
Testo completo
10
Rennie, Shona. "Reproductive investment, gamete quality and diet in farmed salmonids". Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418907.
Testo completo
11
Byrne, Hazel. "The welfare and quality of farmed salmonids at harvest". Thesis, Robert Gordon University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248695.
Testo completo
12
Duncan, Sarah Katharine. "Egg quality and the over-ripening process in salmonids". Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359032.
Testo completo
13
Belmonte, da Silva Rodrigo Caetano. "Saprolegniosis : studies of the host-pathogen interaction in salmonids". Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=220447.
Testo completoAbstract (sommario):
Saprolegnia is a fresh water fish parasite responsible for significant economic losses in the aquaculture industry worldwide. The disease caused by this organism is termed saprolegniosis, being characterized by a mycosis-like infection of gills and fish skin. Without sustainable treatments available for controlling or preventing saprolegniosis, it has become a significant problem especially for salmon farming, frequently affecting the fish after vaccination. Little is known regarding how the fish immune system responds to infection and such information is vital for developing future treatments and preventive measures to saprolegniosis. To study the immune response of Atlantic salmon to Saprolegnia, a detailed immune profile of experimentally infected presmolts was performed by analyzing the expression levels of several immunity-related genes. Infected fish exhibit a very strong inflammatory response while the majority of genes associate with the adaptive immunity were found to be down regulated. The mechanisms behind this response were then investigated: It was discovered that the cell wall of Saprolegnia can be recognized by fish immune cells, triggering an inflammatory response. A protease secreted by the parasite that has the ability to degrade fish antibodies was identified and, for the first time in an oomycete, the production of prostaglandin E2 was characterized, a molecule that was later shown to potentiate inflammatory responses while suppressing host adaptive immunity genes. Lastly two metabolic pathways of the oomycete were explored as novel targets for control, prostaglandin and sterol metabolism by the use of cyclooxygenase and CYP51 inhibitors, respectively.
14
Brackley, Robert. "Interactions between migrating salmonids and low-head hydropower schemes". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7871/.
Testo completoAbstract (sommario):
The redevelopment of existing riverine barriers with modern hydropower turbines is becoming increasingly prevalent on main stem rivers with valuable stocks of migratory salmonids. This is a concern because these fish rely on longitudinal connectivity to complete their lifecycles, and modifications for hydropower could jeopardize that connectivity by obstructing or injuring migrating fish. In order to exploit very low head hydropower potential, novel turbine types are emerging. The Archimedean screw hydropower turbine is one such technology which is becoming increasingly popular for low-head applications. However the impact of these turbines on fish movements remains largely untested. This thesis aims to provide much needed evidence on the effects that these turbines and schemes may have on migrating salmonids. Fixed radio and passive integrated transponder receivers were used to track the downstream movements of wild migrating juvenile salmonids through a low-head Archimedean screw hydropower scheme. Atlantic salmon smolts were found to pass through the alternative routes of the turbine and main river channel in proportion to flow through these channels. Passage times were generally fast through both routes (median = 17.6, range = 5.1-905.6 minutes over the 350m scheme extent, for radio tagged fish), and longer passage times were associated with daytime presence in both routes. The majority of PIT tagged Atlantic salmon and sea trout smolts that passed through the 100 m long turbine channel, did so in under 27 minutes (median = 6.8 minutes), whilst a few fish had much longer passage times, associated with daytime presence. There were no differences in onward survival (measured as distance survived downstream) between turbine passed and non-turbine passed migrants. Atlantic salmon smolts were passed through an Archimedean screw turbine to test for harmful effects from the turbine, with comparison to equivalently handled non-turbine passed smolts. There was no evidence of visible damage aside from low to moderate scale loss, which was not significantly associated with turbine passage. Blood chemistry parameters were used to test for subtle turbine-induced damage. This novel application of these techniques did not yield conclusive results, but serves as a useful precedent for future studies. Radio and PIT telemetry equipment were used to investigate the movements of upstream migrating adult salmonids at three separate low-head hydropower schemes which may act as obstacles to migration. These schemes each had distinct configurations and flow management regimes. Movements within, and progression beyond these schemes varied substantially between sites, and in some cases were related to flow management parameters. Whilst not conclusive, the results suggest that scheme configuration and the management of flows influence the time that fish spend at such schemes, and the proportion of fish that ascend beyond them. With the global shift towards renewable energy generation, the exploitation of running water for hydropower is likely to become increasingly pervasive. The results of these studies provide valuable information for the informed and ecologically sustainable development of low-head hydropower schemes.
15
Martin, Niall M. B. "Protein turnover in Salmonids : sexual maturation and hormonal control". Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU548688.
Testo completoAbstract (sommario):
Aspects of tissue protein metabolism were studied in different groups of Atlantic salmon (Salmo salar). Firstly, 2 groups of sea water salmon were fasted for 3 and 5 days, prior to the measurement of tissue fractional rates of protein synthesis (ks, %day), using the method of 3H-phenylalanine flooding. The sensitivity of liver and gill to a short-term fast was indicated by their reduced rates of ks, while in other tissues such as ventricle, stomach and red muscle protein synthesis was unaffected. Both liver and gill are tissues which show the greatest capacities to synthesise protein, expressed by their high RNA contents. The response of tissue protein metabolism to sexual maturation was investigated in 2 groups of salmon undergoing river migration, tissues were analysed in both July salmon (sexually maturing) and in more mature October salmon. White muscle contributed most of the amino acids required during maturation, denoted by the high loss of protein and RNA from the flesh of the salmon by October. Red muscle, gill and ventricle were tissues which were protected during maturation, showing only slight changes in rates of protein metabolism. Liver, stomach and ovary on the other hand increased their RNA and protein contents, and showed increased rates of protein synthesis. The liver however, displayed a greater increase in its RNA concentration than protein i.e. the liver by October had increased its capacity to produce large amounts of export proteins. Despite the overall loss by stomach and other visceral tissues of protein and RNA, the stomach by October showed a dramatic 5-6 fold increase in its rate of protein synthesis. It was concluded that smooth muscle may have a particular role or function in the sexually mature fish. Factors controlling these in vivo changes in protein synthesis were investigated using rainbow trout (Oncorhynchus mykiss) isolated hepatocytes and a smooth muscle preparation in vitro . Anabolic actions on hepatocyte protein synthesis were exhibited by insulin, thyroxine and in the absence of fetal calf serum by triiodothyronine. The synthetic glucocorticoid, dexamethasone, unlike its actions in muscle, also exhibited an anabolic action on hepatocytes, by raising RNA and protein levels in cells from immature fish, while increasing protein synthesis rates in liver cells of sexually mature fish. Estradiol, like dexamethasone, stimulated rates of protein synthesis over 24 hours. However, hydroxyprogesterone caused no change in protein synthesis and decreased the effect of estradiol. Estradiol also increased protein synthesis rates in smooth muscle by some 30%. However, hydroxyprogesterone, as in liver cells, caused no stimulation of protein synthesis and again decreased the estradiol stimulated ks. It was proposed that estradiol is one of the factors involved in increasing the ks in the stomach of the sexually maturing salmon, while progesterone regulates the action of estradiol towards the end of sexual maturation, when such an effect of estradiol on liver and smooth muscle ks is unnecessary.
16
Forsberg, Lars. "Genetic Aspects of Sexual Selection and Mate Choice in Salmonids". Doctoral thesis, Uppsala universitet, Populationsbiologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8837.
Testo completoAbstract (sommario):
The long-term genetic consequences of supportive breeding programs are not well understood. Nevertheless, stocking populations with hatchery-produced fish to compensate for losses of natural production are common practice, for example after constructions of hydroelectric power dams. Hatcheries typically fertilize eggs using ‘mixed-milt fertilizations’, without consideration to natural reproductive behaviours, and hence, natural selective regimes would be altered. Here, a series of experiments with focus on Mhc and mate choice in a population of brown trout (Salmo trutta L.) with a history of long-term stocking are presented. The major histocompatibility complex (Mhc) constitutes of genes coding for antigen presentation in the vertebrate immune system. In addition to the immunological function, Mhc genes might also influence reproductive behaviours such as mate choice. For example, in some species individuals are able to recognize Mhc genotypes of potential mates and to some extent base their mate choice on this information. Here, I address these questions on brown trout. Can the phenomena be observed in brown trout? Could such mechanisms help individuals to avoid inbreeding, or are other mechanisms important? How does the artificial rearing of fish for enhancement of natural populations relate to these issues? The results presented here, in combination with previous work, shows that several factors are important in the process of pair formation in salmonid species. For example, females of the studied population used more than a single criterion when choosing among the available mates Mhc genes and males with certain Mhc genotypes achieved more matings, possibly an effect from increased fighting ability. Further, the population appears to contain an unnatural high level of Mhc variation, and some results indicate that the population might suffer from outbreeding depression at the Mhc. These negative effects are most likely derived from compression of sub-populations after dam-construction, in combination with supportive breeding with no consideration to natural spawning behaviour.
17
O'Keefe, Robyn. "The feeding response and growth of diploid and triploid salmonids". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ46460.pdf.
Testo completo
18
Jones, Wayne. "Modelling the growth and resource allocation dynamics of juvenile salmonids". Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248333.
Testo completo
19
Clease, Derek Fraser. "Evolutionary divergence in Philonema (Nematoda; Philometridae) parasites of B.C. salmonids". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28942.
Testo completoAbstract (sommario):
Philonema (Nematoda; Philometridae) from anadromous hosts, sockeye salmon (Oncorhynchus nerka), and non-anadromous hosts, rainbow trout (Oncorhynchus mykiss) , were studied in order to determine if hosts with different life histories were infected with the same or different species of Philonema. Worms from the two host species were morphologically indistinguishable. However, electrophoretic banding patterns produced by restriction enzyme digestion of DNA extracted from Philonema demonstrated the presence of two genetic types corresponding to the two host species. This supports the idea that at least two species of Philonema are endemic in British Columbia. Philonema oncorhynchi Kuitunen-Ekbaum, 1933 is a parasite of sockeye salmon which undergo a long ocean migration before returning to freshwater to spawn, while P. agubernaculum Simon and Simon, 1936 is a parasite of rainbow trout (and other salmonids) which live in lakes.
Kokanee (O. nerka kennerlyi), a non-anadromous offshoot of sockeye, were infected with the same worm as sockeye probably because the two hosts have similar life histories. Steelhead smolts, anadromous O. mykiss, contained worms identified as P. agubernaculum. This likely represented an accidental infection because steelhead do not usually contact Philonema.
Philonema were examined from various localities in B.C. Philonema agubernaculum showed population divergence corresponding to the different geographic localities from which it was collected. This likely reflects the isolation of these parasite populations in unconnected watersheds. Philonema oncorhynchi showed polymorphisms spread throughout many of the populations. The lack of population divergence probably results from gene flow between parasite populations brought about by wandering hosts.Science, Faculty of
Zoology, Department of
Graduate
20
Parkyn, Daryl Charles. "Visual biology of salmonids with special reference to polarised light sensitivity". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34280.pdf.
Testo completo
21
Ojala, Jeffrey Veikko. "Invertebrate phenology and prey selection of three sympatric species of Salmonids". Connect to this title online, 2008. http://scholarworks.umass.edu/theses/97/.
Testo completo
22
Østergaard, Anders Erlang. "Discovery and expression of novel immunoglobulin-like transcripts (NILTs) in salmonids". Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=158294.
Testo completoAbstract (sommario):
Three new NILT genes were successfully cloned and characterized from rainbow trout, with one NILT alternatively spliced into a long isoform containing two Ig domains and a short isoform containing one Ig domain. The expression of NILTs was studied in six different tissues and two different cell lines, with expression apparent in immunologically important tissues. Furthermore, phylogenetic analysis showed that NILTs are more closely related to triggering receptor expressed on myeloid (TREM) cells and Nkp44 from humans than to NITRs from rainbow trout. The genomic organisation and structure of the multigene family of NILTs in Atlantic salmon was investigated using a BAC sequencing approach. This revealed the presence of six novel NILT genes, which either contained one or two Ig domains and several immunoreceptors tyrosine-based inhibitory motifs (ITIMs) in the cytoplasmic region. By homology search two NILT-like genes in zebrafish (Danio rerio) located on chromosome 1 have been obtained. Chromosome 1 in zebrafish also contains the Dare-ZE genes, which are equivalent to the human MHC class I genes located on chromosome 6. The distance between the later and the TREM genes on chromosome 6 is similar to the distance between the NILT-like genes and Dare-ZE genes on zebrafish chromosome 1. In addition, two NILT-like Ig domains were obtained from the green spotted pufferfish (Tetraodon nigroviridis), putatively part of the same receptor. The results will contribute to our knowledge of the immune system in fish and provide useful information for the control of inflammatory processes in salmonids.
23
Suter, Hayley Claire. "The effects of maternal steroids on individual variation in juvenile salmonids". Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/5347/.
Testo completoAbstract (sommario):
The research described in this thesis examined whether concentrations of maternal steroids in the egg at fertilisation can influence ecologically important physiological and behavioural traits in juvenile salmonids. I have addressed four questions: Can experimental manipulation of egg steroid concentrations influence offspring physiology and behaviour? What is the extent of natural variation in the steroid content of a female's eggs at fertilisation? Does natural variation in egg steroid content influence offspring phenotype? Does maternal social status influence maternal and egg steroid concentrations. Experimental elevations of the cortisol and testosterone content of brown trout eggs (Chapter 2) indicated that concentrations of these hormones may influence juvenile size, resting metabolic rate and social status. However, there was great inter-family variation in the effects of treatment, and the possibility that the variation observed is due to differences in rearing environments rather than treatment is an equally plausible hypothesis. Thus, maternal steroids in the eggs at fertilisation may be able to influence aspects of juvenile physiology and behaviour that are associated with early competitive ability and survival, but so too many undetected variation in the rearing environment. To determine the scope for an effect of maternal steroids in the eggs, I then investigated the degree of intra-female variation in egg steroid content, both before (Chapter 3) and after ovulation (Chapters 3 & 4). Before ovulation, follicle cortisol content and weight varied between different regions of the ovary, but patterns of variation were not consistent between females. In some cases when females were allowed to spawn naturally, egg steroid content varied between nests deposited by the same female, but patterns of inter-nest variation were not consistent between the eggs of different females. I suggest that the steroid content of ovulated eggs can change while eggs are retained in the body cavity, resulting in inter-nest variation.
24
Addley, R. Craig. "A Mechanistic Approach to Modeling Habitat Needs of Drift-Feeding Salmonids". DigitalCommons@USU, 1993. https://digitalcommons.usu.edu/etd/5808.
Testo completoAbstract (sommario):
A mechanistic model is developed to determine the habitat needs of drift-feeding stream salmonids from the direct cause-and- effect relationships of environmental and physiological variables on net energy intake (NEI). The model determines NEI by subtracting energy costs (basal metabolism , swimming cost, digestion cost) and losses (egestion and excretion) from the gross energy intake obtained as a result of simulated prey capture. The prey capture portion of the model utilizes components o f the predation model of C.S. Holling and the prey capture model of N.F. Hughes and L.M. Dill to determine the rate of prey capture (gross energy intake) as a function of fish size, water velocity, water depth, water temperature, and the amount of drift. Physiological input parameters for the model are estimated from the literature.
Two separate validation tests of the model's ability to predict stream habitat use of trout, primarily cutthroat trout (Oncorhynchus clarki), in St. Charles Creek, Idaho, are presented. In both cases, the NEI model closely predicts the stream habitat that different size classes of fish utilize. The validation tests provide strong evidence that drift-feeding fish utilize stream habitats that provide high rates of NEI as determined by the model.
Sensitivity and simulation analyses of the model are used to identify the most important input parameters and to illustrate in terms of energetics why drift-feeding fish utilize various habitats. Model simulations explain why fish utilize deeper and faster habitats as they get larger and why they utilize slower habitats in the winter. In addition, it is shown that streams with high drift rates should theoretically provide more usable salmonid habitat than similar streams with lower drift rates.
25
Gauld, Niall Roderick. "The behavioural ecology of migratory salmonids in the River Tweed, UK". Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10722/.
Testo completoAbstract (sommario):
This study investigated various life history stages of salmonids within the River Tweed, UK with a focus on migratory movements. The River Tweed is a large upland river situated on the border between Scotland and England and is home to some of the healthiest stocks of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) in the UK. The research undertaken as part of this thesis aims to assess how management can be improved to aid the migration of salmonids moving within freshwater. This is of particular importance due to increased demand for renewable energy including small scale hydropower as well as legislation that demands improved fish passage within rivers such as the Water Framework Directive. Sea trout smolts were captured and acoustic tagged to assess the roles that in river obstructions such as weirs play on their migration between years with varying river flow. The two study years varied radically in flow levels due to the incidences of hydrological drought in 2010 significant differences were observed in the degree of delay smolts experienced at weirs as well as differing responses to flow during years. Sea trout and salmon were acoustic tagged and tracked during their freshwater spawning migration. The aim of the study was to examine the interspecific differences in spawning migration such as spawning location and movement rate during migration. By looking at migration rate of sea trout and salmon it was observed that both species decreased their migratory rate the further into the river system they moved. It was also observed that sea trout and salmon spawned in different locations, with sea trout using tributaries and salmon using lower stretches of the Tweed. The small scale movements of freshwater resident trout was studied. Freshwater resident trout tend to have relatively small home ranges and often hold a territory within their home range. As a result they also tend to rapidly home back to their territory after being displaced from it. As such, the study aimed to assess the degree to which brown trout home after being displaced, particularly whether being offered a choice of empty territories at their site of displacement would affect their homing behaviour. The study found that there was no apparent difference in homing behaviour observed between treatment groups offered empty territories at their site of displacement compared to controls that were displaced into fully populated sites. Continued research into the behaviour of salmonid species is important due to increasing demand on water resources, future conflict between man and fishes water needs is inevitable.
26
Von, Schalburg Kristian Robert. "The gonadotropin-releasing hormone gene : characterization, regulation and expression in two salmonids". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ36651.pdf.
Testo completo
27
Washburn, E. J. "Factors influencing salmonids use of an estuarine 'pool and weir' fish pass". Thesis, Swansea University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639353.
Testo completoAbstract (sommario):
The construction of a partial exclusion amenity barrage across the lower estuary of the River Tawe, South Wales, was completed in 1992. The structure includes a pool and weir fish pass consisting of 16 pools interlinked by deep notches in alternately downstream and cross facing traverses. Modifications to the fish pass weirs were carried out at the end of June 2000 in order to address the problem of excessive turbulence within the pools. The primary aim of this thesis was to examine the effectiveness of the modified fish pas under a range of environmental conditions. Underwater video was selected as the most suitable method for monitoring fish use of the pass and a system was designed and installed below the fish pass exit notch. The effects of time of day, tidal state, river flow volume and water quality on fish use of the modified pass were examined. Diel and tidal rhythms appeared to have the greatest impact on fish movements. The majority of fish exited the pass during daylight, supporting the hypothesis that fish utilise visual cues to negotiate obstacles. The timing of movement during tides which completely inundated the fish pass suggested that fish were using the rising tide to aid ascent, however a greater number of fish used the pass during non-inundating tides when this was main route past the barrage. Fish use of the pass appeared to be stimulated between river flows of 3.00 – 6.99 m3 s-1 and 10 – 10.99 m3 s-1, and there was evidence that salmonids use of the fish pass increased in response to changes in flow. Dissolved oxygen concentrations remained above levels which would affect the swimming ability of fish, although oxygen supersaturation may potentially cause periodic problems.
28
Watz, Johan. "Winter behaviour of stream salmonids: effects of temperature, light, and ice cover". Licentiate thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26809.
Testo completoAbstract (sommario):
In boreal streams, stream salmonids typically face low water temperatures and variable ice conditions during winter, and thus stream salmonids are expected to use different behavioural strategies to cope with these environmental conditions. The studies presented in this thesis explore how temperature, light intensity, and surface ice affect salmonid behaviour, with focus on drift-feeding and ventilation rates. The first paper reports results from a laboratory study designed to measure prey capture probabilities and reaction distances of drift-feeding Atlantic salmon, brown trout, and European grayling at light intensities simulating daylight and moonlight at seven temperatures ranging from 2 to 11°C. There was a positive relationship between water temperature and prey capture probability for all three species at both light levels, but the temperature-dependence did not scale according to the Metabolic Theory of Ecology. Reaction distance was also positively related to temperature for the three species, which may explain the temperature effects on prey capture probability. The results from this study should be of interest for those working with energetic-based drift-foraging models. In the second paper, the effects of ice cover on the diel behaviour and ventilation rate of brown trout were studied in a laboratory stream. Ice cover is believed to afford protection against endothermic predators, and thus the need for vigilance should be reduced under ice cover. This hypothesis was tested by observing ventilation rates at night, dawn, and during the day in the presence and absence of real, light-permeable surface ice. Further, trout were offered drifting prey during the day to test if ice cover increased daytime foraging activity. Ice cover reduced ventilation rates at dawn and during the day, but not at night. Moreover, trout made more daytime foraging attempts in the presence of ice cover than in its absence. These results suggest that ice cover affects the behaviour of brown trout and presumably has a positive effect on winter survival. Global warming, by reducing the extent or duration of surface ice, may therefore have negative consequences for many lotic fish populations in boreal streams.BAKSIDESTEXT In boreal streams, salmonids typically face low water temperatures and variable ice conditions from autumn to spring. The studies presented in this thesis explore how temperature, light intensity, and ice cover affect salmonid behaviour, with focus on drift-feeding and ventilation rates. In Paper I, drift-foraging was studied at light intensities simulating daylight and moonlight at seven temperatures ranging from 2 to 11°C. There was a positive relationship between temperature and foraging success at both light levels, but the temperature-dependence did not scale according to the Metabolic Theory of Ecology. Moreover, reaction distance was positively related to temperature. In Paper II, the effects of ice cover on behaviour and ventilation rate of brown trout were studied. Ice cover is believed to afford protection against predators, and thus the need for vigilance should be reduced under ice. This hypothesis was tested by observing ventilation rates at night, dawn, and during the day in the presence and absence of surface ice. Ice cover reduced ventilation rates and increased daytime foraging activity, suggesting that ice cover presumably has a positive effect on winter survival.
29
Petrie, Allan Gilmour. "Potential of PLG and LTB for oral delivery of antigens to salmonids". Thesis, University of Aberdeen, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401271.
Testo completoAbstract (sommario):
Biocompatible polymer poly(lactide-co-glycolide) (PLG) and Escherichia coli heat labile enterotoxin B-subunit (LTB) were investigated with regards to their potential for delivering antigens following oral delivery to salmonids. A commercial immersion vaccine against furunculosis was encapsulated within PLG microparticles and delivered to Atlantic salmon by oral intubation and intra-peritoneal injection. Following delivery, antibody responses and protection against lethal challenge with Aeromona salmonicida were minimal. SEM and protein studies of particles indicated that encapsulation of bacterial cells was sub-optimal. Adjuvant effect of PLG microparticles containing a model protein antigen (human gamma-globulin) was investigated following intra-peritoneal injection to rainbow trout. Release of protein from the microparticles was determined in-vitro. Specific antibodies were determined at set time points following injection by ELISA and no detectable immune response was measured in fish where protein encapsulated within PLG was delivered. This may be explained by the fact that in-vitro release of HGG from microparticles over the experimental period was minimal. The ability of Atlantic salmon to take up microparticles was investigated following anal and oral intubation of fluorescent microspheres of known sizes. Following anal intubation, microspheres in the range of 0.1 to 3mm, were detected within spleen and kidney sections. The route of uptake of microspheres was not determined. Following oral intubation, microspheres were detected within the hindgut lumen, although not to the same degree as following anal intubation, and no microspheres were detected within kidney or spleen sections. Incorporation of plasmid DNA vaccine into microparticles or adsorption onto positively charged microparticles were investigated. Both encapsulation within and adsorption onto charged PLG microparticles was demonstrated although technical difficulties were incurred in producing quantities sufficient for immunisation studies. The potential of LTB as an antigen carrier molecule was investigated using recombinant LTB produced within transgenic potato tubers.
30
Roberts, Laura Jayne. "Improving the survival and fitness of hatchery-reared salmonids in restoration programmes". Thesis, Swansea University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678416.
Testo completo
31
Delfosse, Cyril. "Méthodes d'évaluation et de contrôle du stress chez les salmonides d'élevage : Implications sanitaires, zootechniques et environnementales". Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0003/document.
Testo completoAbstract (sommario):
De l’éclosion à l’abattage, le saumon Atlantique et la truite arc-en-ciel d’élevage sont soumis à divers événements inducteurs de stress. Le stress influe directement sur la physiologie, le comportement et les performances zootechniques des animaux. Ainsi, l’intérêt grandissant du public pour le bien-être des animaux nous a amené à améliorer les connaissances sur le stress des salmonidés d’élevage pour en proposer des méthodes d’évaluation et de contrôle. Partant de ce constat, nous avons étudié les conséquences de deux situations inductrices de stress et proposé une méthode d’évaluation du bien-être de la truite arc-en-ciel d’eau douce. Nous avons ensuite étudié l’interaction entre stress et pathologie à travers l’exemple du parasite du saumon Lepeophtheirus salmonis. Après avoir mis au point un test d’attractivité du saumon pour ce parasite, nous avons étudié les conséquences du stress aigu puis chronique sur l’attractivité des saumons. Le stress de manipulation augmente l’attractivité des saumons pour le parasite, alors qu’il n’y a pas de différence entre les saumons stressés chroniquement et les témoins. Nous avons ensuite proposé une méthode de contrôle de ce parasite en isolant un sémiochimique issu du mucus de saumon et inhibant l’attachement du parasite. L’ensemble de nos travaux ouvre des perspectives intéressantes quant à l’amélioration des méthodes d’évaluation et de contrôle du stress en élevage des salmonidés. L’étude des conséquences du stress est importante pour mesurer l’impact, à la fois sur le bien-être de l’animal, mais aussi sur les coûts de production. Le sémiochimique inhibiteur de l’attachement du parasite sur le saumon promet de nombreuses études pour comprendre ses mécanismes d’action et son éventuelle utilisation en élevageFrom hatching to slaughter, Atlantic salmon and Rainbow trout are subjected to several stressful events. Stress impairs physiological, behavioral and zootechnical performances of animals. The public interest in animal welfare brings us to study the assessment and control methods of stress in farmed salmonids. To do that, we studied the consequences of two different stressful events and proposed a method for assessing welfare of freshwater Rainbow trout. We also studied the interaction between stress and pathology with the salmon louse Lepeophtheirus salmonis. After developing an attractiveness test of salmon for the parasite, we investigated the influence of shortand long-term stress on salmon attractiveness for the parasite. Handling stress increased attractiveness of salmon for the parasite, while there was no difference between chronically stressed and control salmon. We proposed then a method to control this parasite by isolating a semiochemical which inhibit the hooking behavior of the parasite on the host. These results open interesting prospects for improving the assessment and control methods of stress in farmed salmonids. The investigation of stress consequences on animal welfare and on production performances is crucial. The semiochemical inhibiting the hooking behavior of the parasite on the salmon needs more studies to identify its mechanisms of action for use in farms
32
McKeever, Thomas J. "The estimation of individual fish size using broadband acoustics with free-swimming Salmonids /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34206.pdf.
Testo completo
33
Ang, Keng Pee. "New strategies for feeding salmonids : video monitoring and contrast enhancement of feed pellets". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ46311.pdf.
Testo completo
34
Boyd, James W. "Effects of water temperature and angling on mortality of salmonids in Montana streams". Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/boyd/BoydJ0808.pdf.
Testo completoAbstract (sommario):
In Montana, angling closures are used to protect salmonids from the deleterious impacts of angling at elevated water temperatures (23°C). Catch-and-release angling (CR) studies have reported high levels (30-40%) of salmonid mortality at water temperatures >20°C, but few studies assess CR mortality of salmonids at water temperatures observed in Montana streams during mid-summer (23°C). The primary objective of this study was to measure CR mortality of rainbow trout, brown trout, and mountain whitefish in three water temperature treatments; when daily maximum water temperatures were cool (<20°C), warm (20 to 22.9°C), and hot (23°C). A secondary objective was to assess CR mortality of salmonids angled in morning and evening within water temperature treatments. Based on the literature, mortality of salmonids was predicted to be >30% within the hot treatment and higher in evening than morning. Angling (fly-fishing only) occurred in the Gallatin and Smith rivers. All angled fish were confined to in-stream holding cages and monitored for mortality for 72 h. Mortality of rainbow trout Oncorhynchus mykiss increased to 9% and 16% in warm and hot treatments, respectively. Mortality of brown trout Salmo trutta was (4%) in the hot treatment in the Smith River. Mountain whitefish Prosopium williamsoni had increased mortality in the warm (20%) and hot (28%) treatments in the Smith River. No mortality for any species occurred in either river when water temperatures were <20°C. Mortality of rainbow trout angled in evening was higher than morning in the warm (14%) and hot (16%) treatments in the Smith River. Laboratory results indicated rainbow trout stressed in evening had higher mortality (7%) than those stressed in morning (0%). Angler catch rates were lower for most species in evening than morning angling events; however, catch rates remained high (0.7 fish/h) in several evening angling events. Study results indicate that salmonid mortality rates associated with catch-and-release fly-fishing are higher at elevated (>or equal to 23°C) water temperatures. Although there was a relationship between elevated water temperature and salmonid mortality, most of the mortality estimates were well below the 30% mortality that was predicted.
35
Middlemas, Stuart John. "Interactions between harbour seals (Phoca vitulina) and salmonids (Salmo spp.) in estuarine environments". Thesis, University of Aberdeen, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288379.
Testo completoAbstract (sommario):
There is great interest in the perceived conflict between salmon fisheries and seals, but little information to inform managers. This study therefore explored the interactions between harbour seals and salmonids within an estuarine system, the Cromarty Firth, NE Scotland (57°37’N, 4°21’W). The number of seals using this area in the 2000 pupping season was estimated to be 188 (138-286) using a novel Bayesian framework that corrected counts of seals on land for those remaining in the water. The presence of seals in the mouth of the River Conon, at the head of the Firth, and the occurrence of salmonid otoliths in seal scats, were related to changes in the abundance of adult salmonids. Overall, salmonid otoliths were found in 8% of scat samples and 21% of those collected during July. This represents the highest reported incidence of salmonid otoliths from scat samples collected in the UK; it is not clear if this is due to temporal or geographic differences with previous work. A novel diet estimation technique was constructed based on the assumption that seals may be employing one of a range of possible foraging strategies. This estimator was compared to two established methods and it was found that model choice introduced considerable introduced considerable bias (up to 3x) in the estimated importance of salmonids in the diet. It is unclear which of the models is appropriate and their outputs were combined to represent uncertainty in our estimates of diet more fully. It was not possible to partition consumption of salmonids between salmon and sea trout as otoliths were too badly digested to allow identification of species. A simple food web was used to suggest that removal of seal predation may improve fishery catch by 17% (5-52%). This figure must be treated with caution and potential biases, and caveats, are discussed.
36
Causey, Dwight R. "Proteomic and molecular investigations of links between growth and immune function in salmonids". Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=240038.
Testo completoAbstract (sommario):
The allocation of energetic resources into competing physiological systems is crucial for the survival and fitness of an organism. Maintenance of active growth and effective immune function is energetically costly and therefore, trade-offs should have evolved to optimise the allocation of resources into these systems according to physiological status. While recent studies have begun to elucidate the mechanisms by which cross-talk exists between these two systems, more work is needed to characterise their interactions. A high-throughput proteomics approach was developed to investigate the molecular mechanisms underpinning fast growth and molecular cross-talk between growth and immune function. This approach revealed unique routes to fast growth in two different growth-accelerated coho salmon strains, including increased protein synthesis in fish overexpressing growth hormone (GH) through a focussed up-regulation of translation machinery. Conversely, selectively-bred fish showed more complex alterations in multiple metabolic pathways potentially underlying increased growth and domestication. Additionally, the liver proteome response of rainbow trout to a bacterial challenge unveiled host defence and immune proteins upregulated during the acute phase response (APR), along with candidate proteins involved in re-allocation of energetic resources during an immune response. Additionally, novel genetic expansions of salmonid complement C3 proteins upregulated during bacterial challenge were identified and characterised. Finally, the AMP-activated kinase (AMPK) system was investigated due to its role in managing energetic status, making it an ideal system to investigate crosstalk between growth and immunity. Novel salmonid-specific genetic expansions in AMPK subunits (α, β and γ) were demonstrated and their mRNA level expression analysed in fast-growing fish strains exposed to immune stimuli, where an increase in expression of several subunits was observed for fish overexpressing GH. However, a significant downregulation in expression of several AMPK subunit genes occurred in response to immune stimuli. Overall, this project provides insights into links between growth and immune function in salmonids, which are relevant to the aquaculture industry, where the aim is to maximise fish growth while retaining strong immunocompetence.
37
Robb, David Henry Francis. "Some factors affecting the flesh quality of salmonids : pigmentation, composition and eating quality". Thesis, University of Bristol, 1998. http://hdl.handle.net/1983/c474b238-aff0-4c37-96af-e223c441f6eb.
Testo completoAbstract (sommario):
This thesis is concerned with identifying some of the factors which affect the flesh quality of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). The flesh of any food animal is of utmost importance. Much work has been carried out on the flesh of land animals, but comparatively little is known about the factors which affect the quality of fish flesh. Salmonids have been farmed for a relatively short period of time, but great advances have been made in the techniques for their rearing. Now that the fish can be grown easily, more information is required on the factors which affect their fish quality in order to produce a consistent product. Fish fed a high oil diet have a significantly higher level of flesh lipid than fish of the same size fed a low oil diet (uncertainty p < 0.001). This has implications for the eating quality of the fish as many attributes of the eating quality of smoked salmon are significantly affected by the flesh lipid content. The flesh texture becomes softer and the flavours stronger, apart from salty flavour which decreases dramatically with increasing lipid (p < 0.001). The general effect of increasing lipid is to increase the perception of overall flavour and the overall liking of the product, as judged by the ten person trained taste panel. In contrast there are much fewer effects of the lipid content on cooked salmon and there are no effects on the overall flavour or overall liking (p > 0.05). The colour of the flesh is of great importance to the flesh quality of salmonids. Stress at slaughter is known to affect the muscle chemistry post-slaughter. This work shows that reducing stress at slaughter significantly increases the colour of the flesh, resulting in lower lightness (p < 0.05), an increased red hue (p < 0.05) and reduced opacity (p < 0.05) as measured using the CElab 1976 method. The change in colour is also shown by an increased Roche colour card score using the subjective colour card score (p < 0.05). Reduced stress at slaughter is also found to result in a longer time to the onset of rigor (p < 0.001) and a reduced susceptibility to gaping of the flesh (p < 0.01). Current commercial 'best practice' methods of slaughter were found to be highly stressful to the fish. The red colour of the flesh has been previously reported to reduce during storage, but this research found no changes in the level of the pigment astaxanthin during 12 days of storage of salmon fillets on ice. No effects of the level of astaxanthin or the antioxidant vitamins ascorbic acid and a-tocopherol at slaughter were found on the eating quality of the cooked flesh, either fresh or after 12 days storage on ice. However, many other attributes of the eating quality were significantly affected during the storage period, with increases in many flavours and textures associated with "off' fish. This translated into a significant reduction in the expression of overall liking by the trained taste panel (p < 0.001). The research for this thesis has shown areas where further research is required to investigate factors having effects on flesh quality. The most important of these new areas is the effect of stress level at slaughter on flesh quality. There is a strong possibility that stress at this point has wide ranging effects, the results of which may actually confound improvements introduced into in other areas of quality control unless they are eliminated from salmon farming practices.
38
Brown, Thomas Gordon. "The role of abandoned stream channels as over-wintering habitat for juvenile salmonids". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24488.
Testo completoAbstract (sommario):
The role of ephemeral swamps and intermittent tributaries (off-stream habitat) located on the flood-plain of a west coast Vancouver Island stream (Carnation Creek), as over-wintering habitat, was examined for two winters. All trout (Salmo gairdneri and S_. clarki clarki) and juvenile coho salmon (Oncorhynchus kisutch) off-stream habitat were identified and characterized. Within this habitat: seasonal movement of salmonids was noted, coho growth rates were measured, salmonid populations were enumerated and contribution of off-stream habitat to the total coho smolt production was estimated.
Coho and trout did not occupy all winter flooded land. Trout occupied intermittent tributaries, while coho occupied both intermittent tributaries and ephemeral swamps. Salmonid use of flooded meadows was negligible. The contribution of off-stream habitat to the watershed's total smolt production was at least 23% and more than 15% came from sites devoid of water in summer.
Seasonal movement of juvenile coho followed a distinct pattern and appeared dependent upon climatic conditions such as magnitude and timing of the first fall (Oct-Nov) freshet. Climatic conditions in spring (March-May) appeared to influence both growth and survival of coho within one small ephemeral swamp.Forestry, Faculty of
Graduate
39
Larsson, Pia L. M. "Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light". Thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-41939.
Testo completoAbstract (sommario):
Stream living salmonids are generally regarded as drift feeders that rely upon their vision when foraging. It has been shown that salmonids become nocturnal at low water temperatures, but have a low foraging efficiency as light intensity is low, due to their dependence upon vision. Shifting from drift feeding to benthic feeding, has been suggested, and analyses of gut contents during winter have shown that the diet of salmonids mainly consists of benthic invertebrates. Most experimental studies of salmonid foraging have only offered the fish drifting prey or only given the fish access to benthic prey in total darkness. Such conditions rarely occur in nature and the importance of benthic foraging to salmonids may therefore have been underestimated. In this study I conducted a stream laboratory experiment to test if low light intensity caused juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) (age 0+) to forage more on benthic than drifting prey. The salmon foraged on both drifting and benthic prey during high light but consumed only benthic prey during low light (by one of six fish). Trout foraged on both drifting and benthic prey during both high and low light, but foraging efficiency was lower during low than high light and foraging efficiency was lower for benthic prey than for drifting prey. These results indicate that both species forage more opportunistically than previously thought.Strömlevande laxfiskar anses generellt vara driftätare som förlitar sig på synen när de födosöker. Det har visats att laxfiskar blir nattaktiva vid låga vattentemperaturer, men har en låg födosökseffektivitet då ljusintensiteten är låg, på grund av sitt beroende av synen. Skifte från driftätande till att äta bentiska byten, har föreslagits, och analyser av maginnehåll under vintern har visat att laxfiskars diet huvudsakligen består av bentiska evertebrater. De flesta experimentella studier av laxfiskars födosök har endast erbjudit fisken driftande byten eller endast gett fisken tillgång till bentiska byten vid totalt mörker. Sådana förhållanden förekommer sällan i naturen och betydelsen av bentiskt födosök för laxfiskar kan därför ha underskattats. I den här studien utförde jag ett experiment i en laboratorieström för att testa om låg ljusintensitet fick juvenil Atlantlax (Salmo salar) och öring (Salmo trutta) (ålder 0+) att födosöka mer på bentiska än driftande byten. Laxen födosökte på både driftande och bentiska byten vid högt ljus men bara bentiska byten åts vid lågt ljus (av en av sex fiskar). Öringen födosökte på både driftande och bentiska byten vid både hög och låg ljusintensitet, men födosökseffektiviteten var lägre vid låg än hög ljusintensitet och födosökseffektiviteten var lägre för bentiska än förbiflytande byten. Dessa resultat indikerar att båda arterna födosöker mer opportunistiskt än vad man tidigare ansett.
40
Lowther, Alan B. "Development, expansion, and evaluation of release-recapture survival models for Snake River juvenile salmonids, with new algorithms allowing time-dependent individual covariates /". Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/6378.
Testo completo
41
Bettge, Kathrin. "The proliferative kidney disease of salmonids : dynamics of the parasite in the fish host /". [S.l.] : [s.n.], 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000286556.
Testo completo
42
Aminirissehei, Abdolhossein. "Passive immunization of salmonids against furunculosis and vibriosis with chicken egg yolk immunoglobulins (IGY)". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61527.pdf.
Testo completo
43
Murua, Jefferson. "The role of social rank in the development, physiology and reproductive strategies in salmonids". Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/104585.
Testo completoAbstract (sommario):
Salmonids naturally organise into social hierarchies both in the wild and aquaculture. This thesis investigates how social rank influences the physiology and development of salmonids with different life strategies using Atlantic salmon (Salmo salar) as a model. In broad terms two types of studies were conducted. Firstly osmoregulatory traits of freshwater parr prior to smolting, maturing or remaining immature where investigated using Na+ gill uptake kinetics. Highly distinct patterns emerged, especially for Na+ uptake affinity, between future alternative phenotypes, which could potentially be used as an identification tool in otherwise visually identical fish. Examination of Na+ uptake kinetics from a social status perspective revealed that first and intermediate ranked fish, which received less aggression and had lower cortisol, were better prepared for sea water entry. In the second batch of studies brain serotonergic activity (5-HIAA/5-HT), a key regulator of agonistic behaviour in vertebrates, was examined in a range of social conditions. First, the stability of social ranks was tested by food manipulation. The most dominant fish were able to retain their high status even after being kept in nutrient poor conditions. High status was associated with a high standard metabolic rate (SMR) and low brain 5-HIAA/5-HT. Secondly, studies on hierarchies with marked bimodal size asymmetries showed that upper modal group fish (UMG) became dominant. Despite being subordinate lower modal group (LMG) individuals showed similar growth rates, serotonin turnover and cortisol to UMG fish, possibly due to high aggression and fin injury sustained by high rank fish fighting for dominance. Thirdly, the association between social dominance and developmental pathway was examined in size-matched groups of immature parr and precocious parr, with the latter obtaining higher social positions and showing higher aggression. Brain serotonin turnover revealed higher 5-HIAA/5-HT in immature parr, a phenotypic distinction that was also identified in immature salmonids in aquaculture. Plasma samples from alternative life histories (immature parr, precocious parr and smolts) were also used for a preliminary investigation of potential metabolite signatures utilising metabolomic techniques.
44
Brockmark, Sofia. "Environmental influences on the behavioural ecology of juvenile salmonids : the importance of rearing density /". Göteborg : Department of Zoology, Animal Ecology, University of Gothenburg, 2009. http://hdl.handle.net/2077/21127.
Testo completo
45
Jaramillo, Torres Hugo Alexander. "Intestinal health and microbiota in salmonids : the impact of probiotics under potentially stressful conditions". Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/9705.
Testo completoAbstract (sommario):
The intestine and associated bacterial microbiota have a central role the physiology and homoeostasis of the host. The understanding of how farming conditions affect the intestine and associated microbiota of fish is the high importance to counteract the potential threats to health and welfare. Thus, this thesis aims to understand the role of stressful husbandry conditions on the intestine and associated microbiota of rainbow trout and Atlantic salmon. Within this context, the role of Pediococcus acidilactici as health promoter was also investigated Chapter 3 investigated the replacement of fishmeal by different plant protein ingredients in rainbow trout. The results of this chapter revealed that the effect of P. acidilactici on the microbiota of distal intestine in rainbow trout was dependent on the ingredients of the diet. The results also showed that the FM substitution induced major changes in the intestinal microbiota. Moreover, the modulation induced by plant-based diets on the microbiota varied according to the ingredients used. Chapter 4 studied the effect of dietary oxytetracycline in the distal intestinal microbiota of rainbow trout and the role of P. acidilactici to ameliorate the impact of antibiotic therapy. Experimental groups fed the diets with oxytetracycline had substantial changes in the distal intestinal microbiota including a decrease in the bacterial diversity. P. acidilactici did not ameliorate the effect of antibiotic therapy in the intestinal microbiota. Chapter 5 used Atlantic salmon during smoltification to study the changes in the microbiota of distal intestine and the role of P. acidilactici to promote intestinal health. The results showed that bacterial communities in the mucosa differed from the digesta. Seawater transfer and P. acidilactici had significant changes in the intestinal microbiota of both mucosa and digesta. However, the modulatory effect of both factors evaluated was larger in the mucosa-associated microbiota than in the digesta-associated microbiota. Furthermore, P. acidilactici induced a significant increase in antiviral-related genes. Chapter 6 investigated the replacement of fish oil by rapeseed oil alone or combined with P. acidilactici on the intestinal health and microbiota of two intestinal regions in Atlantic salmon. Replacement of fish oil by rapeseed oil alone or in combination with P. acidilactici supplementation did not induce major changes in the intestinal health and microbiota. The bacterial communities found were significantly different between the pyloric caeca and mid-intestine. In conclusion, this thesis contributes to new knowledge regarding the effect of dietary supplementation of P. acidilactici and the impact of different potential challenging factors in the health and intestinal microbiota of farmed salmonid species.
46
Power, Elizabeth A. "Effects of log storage on zooplankton and juvenile salmonids in Babine Lake, British Columbia". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26516.
Testo completoAbstract (sommario):
Effects of log storage on water quality, zooplankton and juvenile salmonids were investigated at Babine Lake, British Columbia in a series of enclosure, field and laboratory experiments. Enclosures were stocked with lake zooplankton and treated with lodgepole pine (Pinus Contorta) and white spruce (Picea glauca) logs for two 25 day periods. Oxygen depletion, to levels as low as 2.5 mg/l, and increased lignin and tannin (L-T) concentration (a measure of wood leachate) occurred in log treated enclosures. Zooplankton density significantly decreased with increased log number, but changes in community diversity were not consistent.
In field studies at Morrison Arm, Babine Lake, extreme oxygen depletion (<1 mg/l) was observed in localized surface waters within a log storage area. Dye tracer studies within the log bundles implied reduced water movement, which may be involved in oxygen depletion. Local zooplankton abundance was usually lower at log storage sites than nearby undisturbed littoral sites and sockeye fry held in situ for 24 h periods acquired fewer and/or a lower diversity of prey items in log storage areas.
Laboratory toxicity studies indicated that spruce bark leachates were more toxic than pine, but lethally toxic bark leachates had higher L-T values than those measured in the Morrison Arm log storage area. In chronic Daphnia bioassays, mortality rates significantly increased and fecundity rates significantly decreased during long term exposure to low concentrations of bark leachates. Results of enclosure experiments, field studies and laboratory bioassays provide evidence that zooplankton are reduced in abundance by conditions which accompany log storage, possibly through chronic toxicity or reduce fecundity. Because fry diet was sensitive to small changes in food abundance, there is potential for reduced survival of sockeye fry exposed to low oxygen concentrations and reduced food levels.Science, Faculty of
Zoology, Department of
Graduate
47
Mazur, Carl François. "Growth, incidence of bacterial kidney disease and immunological function of salmonids reared in captivity". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30127.
Testo completoAbstract (sommario):
Pacific salmon reared commercially off of the Coast of British Columbia suffer great mortality losses to Bacterial Kidney Disease (BKD), caused by the diplobacillus bacterium Renibacterium salmqninarum. This thesis investigates the effects of environmental conditions on the growth performance and disease susceptibility of salmonids reared in captivity. I found that growth rate of chinook salmon was significantly higher in fish fed to 100 compared to 67 % of satiation during the first 175 days of saltwater rearing but not during the first winter. Feed coversion rate was significantly higher for fish fed at 100 % of satiation compared to 67 % of satiation and higher during the winter compared to summer and fall, irrespective of feeding level. Mortality rates were significantly higher during the summer than during the fall or winter, irrespective of experimental treatment. The last BKD sampling period (day 263) revealed that infection rates were directly proportional to stocking densities of 1.5 to 4 kg.m⁻₃. Hatchery-reared chinook salmon held in freshwater aquaria had significantly lower hematocrit and plasma cortisol concentration increases in response to increased stocking density than did their wild counterparts. Crowding of hatchery-reared and wild chinook salmon resulted in equally increased mortality rates for both groups of fish. Day 33 plasma cortisol concentrations in Atlantic salmon held at three stocking densities were directly proportional to stocking densities of 8 to 64 kg.m⁻₃. The ability of anterior kidney lymphocytes from these fish to produce antibody-producing cells was inversely proportional to the density at which the fish were held.Land and Food Systems, Faculty of
Graduate
48
McCarthy, Una. "Piscirickettsia salmonis : characterisation, infection and immune response in salmonid fish". Thesis, University of Stirling, 2005. http://hdl.handle.net/1893/2711.
Testo completoAbstract (sommario):
The pathogen Piscirickettsia salmonis, has been isolated from all species of salmonid and has been found in Chile, Canada, Ireland, Norway and Scotland. Rickettsia-like organisms from European sea bass (Dicentrarchus labrax) were found to share common antigens with the P. salmonis type-strain, LF-89 using the indirect fluorescent antibody test (IFAT) and immunohistochemistry (IHC). In addition, the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) were compared with those published for P. salmonis strains and showed that the sea bass piscirickettsia-like organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. The ability of P. salmonis to survive and replicate within head kidney (HK) macrophages of rainbow trout infected in vitro was demonstrated using transmission electron microscopy (TEM) at various times post-infection (p.i.). However, macrophages derived from fish vaccinated against P. salmonis appeared to clear in vitro infection more rapidly than macrophages from naive fish. Polymerisation of filamentous actin within the cytoplasm of the host cell is used by some mammalian rickettsiae to achieve intercellular spread by actin-based motility (ABM). Both TEM and confocal microscopy were used to investigate possible actin tail formation by P. salmonis. No evidence of tail formation was found. Respiratory burst (RB) by P. salmonis was measured following exposure of rainbow trout HK macrophages to the organisms in vitro. Because of background stimulation of the RB by growth media and debris from the CHSE-214 cells used to culture P. salmonis, it was not possible to detect any effect of the pathogen on the burst. Schering Plough Aquaculture has developed a recombinant vaccine against P. salmonis. The ability of the vaccine to elicit a memory response against P. salmonis was investigated by measuring three different immune responses: a) the expression of iNOS was measured by reverse transcription polymerase chain reaction (RT-PCR) to detect mRNA levels or by the Greiss reaction to quantify the end-products of nitric oxide metabolism in the serum. Increased iNOS expression was not detected in rainbow trout kidney or serum following vaccination/challenge with P. salmonis. However, iNOS expression was detected in gill tissue from naive trout which suggests that expression may be constitutive in this tissue. b) the production of macrophage activating factor (MAF) by lymphocytes from vaccinated trout, following stimulation in vitro with P. salmonis, was measured by the ability of supernatants from these cells to prime elevated RB in naive macrophages. No difference in priming ability between supernatants from vaccinated and non-vaccinated fish was detected. However, macrophages among the immune leukocytes used to produce the MAF supernatants did exhibit elevated RB compared with macrophages from non-immune fish, suggesting that vaccination had produced a population of lymphocytes capable of priming activation of macrophages. c) by screening individual sera concurrently against the rickettsial and CHSE antigen preparations, the antibody response to P. salmonis could be detected specifically and was found to increase significantly in immunised fish by 6 weeks post-vaccination. Specificity of the response was demonstrated by screening the sera against Aeromonas salmonicida.
49
Jaensson, Alia. "Pheromonal Mediated Behaviour and Endocrine Responses in Salmonids : The impact of Cypermethrin, Copper, and Glyphosate". Doctoral thesis, Uppsala universitet, Ekotoxikologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-121848.
Testo completoAbstract (sommario):
The effects of cypermethrin, copper and glyphosate on the endocrine system and subsequent response to female pheromones were investigated in mature male brown trout (Salmo trutta) parr. Responses measured were the amount of strippable milt, blood plasma levels of both an androgen (11-ketotestosterone (11-KT)) and a progestin (17α,20β-dihydroxy-4-pregnen-3-one (17,20b-P)), and behavioural changes. This was done in a two phased investigation where parr were exposed to one of the following via ambient water: 1) 0.1 or 1.0 μg L-1 cypermethrin, 2) 10 or 100 μg L-1 copper (Cu2+), or 3) 150 μg L-1 glyphosate for a 96 hour period. Phase one was a priming experiment exposing parr to a treatment followed by priming with PGF2α or ovarian fluid (OVF). Atlantic salmon (Salmo salar) parr were, also exposed to glyphosate during phase I. The second phase was centered on behavioural observations. Exposed parr were placed in a 35,000 L stream aquarium together with two ovulated females and four anadromous males. After the experiments a blood sample was taken, milt volumes measured and testes weighed. The plasma was analyzed for 11-KT and 17,20b-P concentrations using radioimmunoassay (RIA). Results from phase I-priming: 1.0 μg L-1 cypermethrin exposure lowered 17,20b-P and 11-KT; Copper exposure lowered milt volumes; glyphosate exposure lowered 11-KT in salmon and raised 17,20b-P in trout. Results from phase II-behaviour: 1.0 μg L-1 cypermethrin exposure lowered 11-KT, milt and spawning behaviour; copper exposure lowered spawning behaviour and raised 11-KT; Glyphosate exposure lowered 11KT; continuous cypermethrin exposure raised 17,20b-P, 11-KT and gave a tendency towards increased aggression. It is concluded that low concentration exposure to the compounds examined can induce negative effects on male salmonid endocrine systems, either through a disruption in the olfactory system or through a direct effect.Extern doktorand från Södertörns högskola
50
Brodeur, Julie C. "Response of cardiac function to environmental contaminants and its significance for energy metabolism in salmonids". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0008/NQ51181.pdf.
Testo completo