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1
Reece, P. "A digestive lipase from salmon (Salmo salar)." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359635.
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A lipase has been partially purified from the bile of salmon (<i>Salmo salar</i>) with an apparent molecular size of 35 kDa and pI of pH 5.25. The enzyme was shown to preferentially cleave C20:5 and C18:4 fatty acids from the liver triacylglycerol of cod (<i>Gadus morhua</i>) as well as hydrolyse sterol and wax ester substrates. The enzyme was shown to hydrolyse substrate optimally at pH 7.1 in the presence of both 0.3M sodium chloride and low concentrations of bile alcohol sulphates. Sodium taurocholate could also partially activate the enzyme in the absence or at low concentrations of the alcohol sulphates. The enzyme was inhibited by 1 mM phenylmethylsulphonyl fluoride and was therefore assumed to be a serine esterase similar to the carboxyl ester lipase of human milk. The salmon enzyme was similarly shown to cleave Sn-2 ester bonds of triacylglycerol after initial hydrolysis of an SN-1(3) bond. The human milk carboxyl lipase was similarly shown to preferentially cleave C20:5 and C18:4 fatty acids from the cod liver triacylglycerol.
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Frenzl, Benedikt. "Understanding key factors associated with the infection of farmed Atlantic salmon by the salmon louse Lepeophtheirus salmonis." Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/22320.
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The objective of the work described in the current thesis was to provide a better understanding of some of the key factors associated with sea louse, Lepeophtheirus salmonis, infection of farmed Atlantic salmon. In Chapter 2, initial work focused on establishing the vertical and horizontal distribution of sea lice copepodids and spatial patterns of on-farm infections. The louse distribution was investigated along the main current gradient across adjacent salmon production pens at three commercial sites. A depth profile for the distribution of larval lice was also established for the top 12 m of the water column at three different locations in close proximity to commercial salmon farms. Within all multi-pen sites there were clear patterns of distribution and infection along the main water current gradient with the abundance of lice in end pens at each site appearing to be different from the central pens. The vertical distribution pattern of free swimming L. salmonis larvae (nauplii and copepodids) showed that the surface 6 m harboured 85.5 ± 1.6 % of the lice present in the water body analysed (0 – 12 m depth), irrespective of sampling date and location. In Chapter 3, further environmental effects / influences on attachment success of the copepodids were analysed using controlled infection challenges. A flume with adjustable flow rates, and controlled light conditions was designed for this study. Flume current velocity was observed to be a significant factor in infection success, with higher infection levels observed at lower current velocities, while higher current velocities were demonstrated to reduce settlement success. At fixed velocity, higher copepodid exposure levels gave rise to higher infection levels, this having a linear relationship suggestive of a lack of competitive effects for space on the fish. Light was also shown to play an important role in host settlement. A positive correlation between increasing light intensity and higher louse attachment success was found for all tested light spectra / wavelengths (white - Halogen, blue 455 nm, green 530 nm and red 640 nm). Observation of an infecting cohort of copepodids showed maximal infection at four days post-moulting with a tail-off of infection by six days post-moulting. However, even under the optimal conditions represented by a flume challenge, including linear water flow, the constraint of copepodids to pass close to the salmon host and the very high exposure levels of copepodids per fish, louse attachment success was still relatively low. Chapter 4 examined implementation of a possible management approach based upon some of the environmental influences observed. This chapter described a study in which environmental manipulation of salmon swimming depth was employed on-site in an attempt to reduce farm infection of Atlantic salmon. The effects of submerged artificial lighting in combination with submerged feeding were tested with respect to salmon swimming depth and sea lice infection, following the hypothesis that L. salmonis infection in a commercial salmon population could be reduced through exposure to deep lighting and feeding. The results of the study suggest that swimming depth manipulation can indeed be used at a commercial scale to reduce salmon lice burdens on Atlantic salmon by physically minimising spatial interactions between the two animals. In the final research chapter (Chapter 5), this thesis examines the question of whether ploidy of the host impacts on sea louse infection levels and whether susceptibility of individual fish is consistent between replicate infections. Results showed that triploid salmon are not subject to higher sea louse infection levels under experimental challenge and farm infection conditions compared to diploid hosts. In addition, triploid fish subject to initial infection, did not become more or less resistant to infection compared to diploids when comparing repeated sea louse infections. In summary, this thesis describes work conducted to analyse key infection pathways and factors influencing infection of Atlantic salmon by sea lice and suggestions made as to how findings may be exploited to reduce louse burdens in Atlantic salmon farming. The practical solutions presented to exploit the results found in this work are currently under consideration by the Scottish salmon industry.
3
Volpe, John. "Ecology of Atlantic salmon (Salmo salar) in British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ62532.pdf.
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McGowan, Colin. "Genetic mapping in Atlantic salmon, Salmo salar, and brown trout, Salmo trutta." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23108.pdf.
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Noguera, Patricia Alina. "In vivo and in vitro studies of Salmon Pancreas Disease Virus (SPDV) in Atlantic salmon (Salmo salar L.)." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33257.
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Salmon Pancreas Disease Virus (SPDV) is the only viral species of the genus Alphavirus, family Togaviridae, affecting fish. SPDV induces two conditions historically recognised independently as Pancreas disease (PD) and Sleeping disease (SD), affecting Atlantic salmon (Salmo salar L) and rainbow trout (Oncorhynchus mykiss), respectively. Infection by SPDV can lead to clinical disease with characteristic acinar pancreatic necrosis and a range of myopathies of the skeletal and heart muscle. Mortality is not a necessary outcome of the disease and usually is not significant. However, affected fish stop eating and therefore present a reduced growth rate and the disease can also leave visible lesions at the fillet level that lead to downgrading at slaughter. SPDV can affect in the fresh and sea water environments, but a higher and most relevant impact reported in the latter. Historically, PD has posed a significant challenge to the Atlantic salmon farming industry in the UK, as well as in other salmon producing countries. This thesis was developed and conducted at Marine Scotland Science (MSS), the Scottish National Reference Laboratory, with the aim to contribute to knowledge gaps identified by the industry and research communities. The focus was on development and improvement of in vivo and in vitro infection models to assist with host pathogen interaction studies. In vivo work was to establish an experimental challenge model to induce SPDV infection in a more natural way than by intra-peritoneal (IP) injection. The first step involved selection of an infective SPDV isolate through a comparative IP challenge study. An infective isolate was then used to establish a co-habitation challenge model in "post smolts", the sea-water stage predominantly affected by PD. Additionally, during this experiment assessment of viral tissue tropism along time and potential intra-subtype differences in infectivity was undertaken. In vitro work accounted for the more innovative part of this thesis with the development, optimization and application of an ex vivo cardiac primary culture originated from Atlantic salmon embryos. While fish origin aggregates of self-contracting cardiomyocytes had been previously isolated and suggested as a robust tool on human biomedical research and pharmacological and toxicology testing, paradoxically very little has been done to explore the approach of ex vivo primary cultures as a disease model with the specific goal for health issues affecting fish. The work involved an adaptation and refinement to produce salmon cardiac primary cultures (SCPCs). Once this was achieved, SCPCs could be kept under laboratory conditions with minimal maintenance for periods up to 6 months. Following this work, SCPCs were successfully challenged with different SPDV isolates as well as another cardiotropic viral agent (Infectious Salmon Anaemia, ISA). The kinetics of SPDV and ISA viral infection and one element of the immune response (i.e. expression of mx gene) were studied. As part of this study, the comparative response of SCPCs of diverse genetic backgrounds (i.e. IPN resistant vs. IPN sensitive) was also assessed. Differences were observed, which highlights potential usefulness of SCPCs to examine genotype-based differences in response to viral disease. Finally, SCPCs were used to examine the SPDV infection cycle ultrastructure by transmission electron microscopy (TEM). This work resulted in novel insights on the replication cycle of SPDV, drawing from the extensive literature in mammalian alphavirus work. With SPDV and other virus associated myocarditis severely affecting Atlantic salmon aquaculture at present, I believe that the SCPCs model represents the most relevant contribution of this PhD.
6
Summers, David W. "Studies of the Atlantic salmon (Salmo salar L.) in Scotland." Thesis, University of Aberdeen, 1992. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=124309.
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Salmon catch data wee analysed from fisheries in or around the mouths of some rivers on the east coast of Scotland spanning the period from the late eighteenth century to the 1980s. It was found that the numbers and sea-age composition of salmon caught and the time of year that salmon were caught varied in the long-term in a coincident manner in different fisheries. These coincident changes in salmon catch data could not be explained by changes in the operation of fisheries and were therefore the results of changes in the population of salmon returning to the Scottish coast. The observed changes in salmon population parameters often coincided with known hydrobiological events in the North Atlantic area, but simple consistent associations between hydrobiological changes and changes in salmon populations were not found. It was concluded that salmon populations were influenced by marine factors but that relationships may be complex. Since there may be several different mechanisms which can cause changes in the sea-age and time of return of salmon, it is not to be expected that a simple causative relationship should be found. The characteristics of salmon which were caught spawning in different burns within the River North Esk system during the winters of 1989/90 and 1990/91 were analysed. It was found that those fish which spawned furthest upstream tended to have a higher sea-age and smolt-age, a smaller length and entered the river earlier in the year than would have been expected if fish entering the North Esk at different times of the year spawned randomly throughout the North Esk system. Likewise those fish which spawned further downstream tended to be large (for their sea-age), had a low sea-age and smolt-age and entered the North Esk late in the year. Although less strong evidence was obtained, a similar pattern was observed for fish which spawned at different times within the spawning season. Those fish which spawned earliest (late October/early November) tended to have entered the river earliest in the year. Analysis of environmental conditions in different burns during the spawning season of 1990/91 suggested that fish which entered the North Esk at different times of year selected particular tributaries to spawn in - the segregation observed was not the result of the chance occurrence of environmental conditions which were conducive to spawning at different times of the year in different burns. The smolt-ages of the adult fish caught in each burn were similar to that of juvenile fish in each respective burn. This suggests that adult fish were returning to the part of the river system in which they were born. Time of return to freshwater and time of spawning were concluded to be adaptations to different environments within the North Esk system. However these characteristics may not be rigorously important and the constitution of a sub-population may alter as a result of selection processes perhaps in the sea.
7
Spaulding, Benjamin W. "Endocrine Disruption in Atlantic Salmon (Salmo salar) Exposed to Pesticides." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/SpauldingBW2005.pdf.
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Browman, Howard I. "Feeding behaviour in fry of Atlantic salmon, Salmo salar L." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63129.
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Levontin, Polina. "Evaluating fisheries management strategies for Baltic salmon : (salmo salar L.)." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443834.
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Tyedmers, Peter. "Salmon and sustainability, the biophysical cost of producing salmon through the commercial salmon fishery and the intensive salmon culture industry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61187.pdf.
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Higgins, Peter J. "Growth, feeding and metabolism in juvenile Atlantic salmon (Salmo salar L.)." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU362531.
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Growth, feeding and metabolism in juvenile Atlantic salmon Salmo salar L. Growth, feeding and metabolism were studied during the juvenile growth phase of Atlantic salmon. Comparisons were made between the faster and slower growing members of sibling populations which formed the upper and lower modes of a bimodal growth distribution. Several new techniques were developed in order to investigate these parameters in small fish. Specific growth rates of marked individuals within the bimodal distribution followed the same pattern of development as the whole population, and appeared to be more closely related to changes in daylength than ambient water temperature. Morphometric assessment of the growth of the swimming musculature showed that both processes of cell enlargement (hypertrophy) and cellular proliferation (hyperplasia) were important. The relative importance of the two processes was dependent on developmental stage and season, although hyperplasia appeared to be more a characteristic of rapid growth than hypertrophy. Histochemical studies demonstrated the presence of "red", "white", and between them a diffuse band of "pink" muscle which appeared to become less evident during the freshwater growth period. Modal differences in food intake were found between October and March, with the upper mode fish feeding optimally whilst the lower mode fish fed at only maintenance levels. Although no differences were found in food turnover rate, upper mode fish demonstrated an elevated temperature specific food intake and gross conversion efficiency. Photoperiod was an important influence on feeding, affecting both the daily feeding pattern, which was suppressed in darkness; and evacuation rate, which was more rapid for fish experiencing an increasing rather than decreasing photoperiod. Upper mode fish and smolts had higher resting rates of oxygen consumption than lower mode fish at two of the experimental temperatures used. Smolts had larger gills than either modal group, although no differences were found between fish in the upper and lower modes. However, upper mode fish had larger hearts than those measured in the lower mode. The higher levels of metabolism usually associated with smolting appeared to be a normal characteristic of the upper growth mode. The parameters studied are discussed in relation to the energy budget, and it is concluded that the two growth modes comprise two distinct "physiological populations" within the sibling group. Photoperiod is considered to be a primary influence on growth, and it is suggested that differential responses to seasonal and daily changes in photoperiod by individuals may account for both the development of bimodality, and provide the means (through an increased daily and seasonal feeding opportunity) by which higher growth rates are sustained by the upper mode fish.
12
Hill, Aaron C. "Sedimentary legacy of sockeye salmon (oncorhynchus nerka) and climate change in an ultra-oligotrophic, glacially-turbid British Columbia nursery lake." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05312007-075732/.
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Hamnes, Frøydis Bolme. "Size-dependent habitat use in juvenile Atlantic salmon (Salmo salar L.)." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13153.
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Cauwelier, Eef. "The nature of intraspecific biodiversity in Atlantic salmon (Salmo salar L.)." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445157.
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The nature of intraspecific biodiversity in the Atlantic salmon was examined, more particularly the issues related to mating between non-natives and natives, and the genetic basis of complex traits, which could be important to aquaculture. These issues were examined in parental, F<sub>1</sub>, BC<sub>1</sub> and F<sub>2</sub> crosses between extremely genetically differentiated populations, i.e. a non-anadromous Canadian and anadromous Scottish populations, and the experiments were carried out in a hatchery. Outbreeding depression, which is defined as the reduction in the offspring fitness caused by the mating of unrelated individuals, was measured directly in relation to survival and indirectly through traits associated with early growth and development in parental, F<sub>1</sub> and BC<sub>1</sub> cross types. The genetic basis of smolification, seawater tolerance and resistance to PKD was investigated in F<sub>2</sub> families. Reduced survival, which was asymmetrical in the BC<sub>1</sub>, was observed in the F<sub>1</sub> and BC<sub>1</sub> cross types, with offspring from one backcross being unviable, whilst viable offspring were obtained from the reciprocal backcross. Growth and development patterns were altered in the F<sub>1</sub> and BC<sub>1</sub> compared to the parental controls, and could be explained by both maternal and additive effects. QTL analysis revealed a number of markers associated with the various phenotypic traits related to smolification, seawater survival and PKD resistance, suggesting polygenic control. Reduced survival and altered growth and developmental patterns in the hybrids could be expected to lead to even more severe outbreeding depression in a selective environment. However, there was also indirect evidence for outbreeding depression in relation to seawater survival and PKD resistance.
15
Gani, Raymond. "Modelling environment dependent growth of juvenile Atlantic salmon, Salmo salar, L." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248698.
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Thomaz, Diogo Miguel Pereira Fernandes. "Alternative life-history strategies in male Atlantic salmon (Salmo salar L.)." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/34249.
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In this thesis I looked at the choice of mating tactics in male Atlantic salmon by determining the fertilisation success of individuals adopting different mating behaviours. In this species, as in most salmonids, males can either become sexually mature early in the life cycle, as small freshwater juveniles called parr, or undergo a sea migration before maturing. The alternative behaviours are thought to be contingent on environmental and social circumstances, although some researchers see them as mixed evolutionarily stable strategies. Here, using the charomid cloning method I isolated eight highly polymorphic minisatellite DNA markers and, using two that showed heterozygosities above 80%, fingerprinted more than 2,000 salmon embryos and measured for the first time the fertilisation success of mature parr and anadromous males in a wild Scottish population. The percentage of eggs fertilised by mature parr was estimated to be between 35% and 40% in this population, more than double the two previous estimates reported in semi-natural environments. In mating experiments in captivity I manipulated the number and body size of parr. Pairs of migrants were allowed to spawn in an enclosure with mature parr. Analysis of paternity revealed a strong correlation (r2=0.95) between parr size and reproductive success. The results also provided further support to a hypothesis predicting negative frequency dependent reproductive success in this species. The results in both the experiments and the field study are used to develop an optimisation model for understanding life history variation in this species. The model assumes that the choice of mating tactics is contingent on body size. General agreement between the results and observations in wild populations is taken as supportive of the important role that environment plays in male mating tactic choice in Atlantic salmon.
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Diamond, Sian. "Mechanisms and consequences of hybridisation between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)." Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42390/.
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Relatively little research has been done to investigate the way postcopulatory, prezygotic mechanisms act to isolate species at the level of the gamete. This thesis uses the naturallyhybridising, externally-fertilising system of Atlantic salmon, Salmo salar, and brown trout, S. trutta, to investigate mechanisms of hybridisation through sperm-egg interactions, much of which is poorly understood. Salmon and trout experience conspecific sperm precedence during in vitro sperm competition experiments, when sperm volumes and release times are equalised. This thesis firstly aimed to explore the dynamics of gametic interactions underlying this reproductive isolation. Manipulating the sperm entry time in interspecific sperm competitions significantly influenced the observed conspecific sperm precedence. A 2 second delay to the entry of conspecific sperm did not give hybridising males first-male sperm precedence, but neither did they gain precedence with paternity being shared between males; suggesting a mechanism of selection for conspecific sperm. Selection mechanisms were investigated through in vitro sperm competitions where egg ovarian fluid type was manipulated. Results showed that conspecific ovarian fluid allowed conspecific sperm significantly higher fertilisation success when competing against heterospecific sperm, regardless of which species eggs were under competition. This is the first evidence for cryptic female choice via a reproductive fluid in an external fertiliser. The second objective of my thesis was to investigate the potential consequences of salmon-trout hybridisation for wild populations. This was achieved through comparing the early life and reproductive fitness of hybrids and pure species. Both reciprocal hybrid crosses had comparable early life fitness to pure species. Importantly however, neither reciprocal cross exceeded pure juveniles for any fitness measures. This suggests the replacement of parental species by hybrids is unlikely. Both hybrid crosses were capable of producing viable sperm and able to fertilise over 50% of both salmon and trout eggs. Neither cross gained paternity success when competing for trout eggs with conspecific males, while very low paternity was gained under sperm competition with Atlantic salmon for salmon eggs. The main threat posed by hybridisation to vulnerable salmon populations appears to come from wasted reproductive effort, through the production of reproductively unfit hybrids. The implications of this are discussed.
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Lund, Bjørnås Kristine. "Modeling Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) responses to river habitat alteration." Licentiate thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-76559.
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Half the world’s river volume is affected by flow alterations and/or fragmentation, a figure that is likely to increase with the current global surge in hydropower development. At the same time, freshwater biodiversity is in rapid decline. In fluvial ecosystems, streamflow is a master variable, shaping riverine species’ habitat over space and time. Atlantic salmon (Salmo salar) and brown trout (S. trutta) are examples of species that need fluvial habitats for reproduction and juvenile rearing, and whose flow needs can come in conflict with hydropower production objectives. This necessitates tools for predicting the effect of fluvial habitat alteration on fish production. In this thesis, I applied the individual-based model inSTREAM to simulate salmon and trout in the Gullspång Rapids, a residual flow stretch of the Gullspång River, Sweden, over a ten-year period. InSTREAM uses sub-daily time steps to simulate individual fish interacting with their biotic and physical environment, and tracks the fitness consequences of their main actions: habitat and activity selection. For inSTREAM input, I had to describe key habitat features, create a 2D hydraulic model of the rapids, model river temperature, and gather data on salmon and trout eco-physiology and life history characteristics in the Gullspång River. I ran simulation experiments varying either flow input, the number of spawners, spawning gravel, shelter and boulder availability, or temperature. Flow alterations had limited benefit. Only the scenario where the current minimum flow was set three times higher yielded increased production, and only for trout. Trout dominated salmon in competition, and production was density dependent. The model predicted that the only way to increase production of both species at current spawner numbers was to add instream structures offering more energetically profitable feeding positions.<br>Half the world’s river volume is affected by flow alterations and/or fragmentation –a figure that is likely to increase with the current global surge in hydropower development. Streamflow shapes the river habitat for species like Atlantic salmon (Salmo salar) and brown trout (S. trutta) –species that need rivers for reproduction and for juvenile rearing. In this thesis, I applied the individual-based model inSTREAM to simulate how salmon and trout interact with the physical and living environment in the Gullspång Rapids, a residual flow stretch in the Gullspång River, Sweden. InSTREAM follows individuals through spawning, egg development, and juvenile rearing until out-migration. I ran simulation experiments over ten years, varying either flow input, the number of spawners, spawning gravel, shelter availability, or temperature. Flow alterations had limited benefit; only in the scenario where the current minimum flow was tripled did production increase, and only for trout. Trout dominated salmon in competition for food and space, and production was density dependent. The model predicted that the only way to increase production of both species at current spawner numbers was to add instream structures offering more energetically profitable feeding positions.<br><p>Article 2 part of thesis as manuscript, now published.</p>
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Grant, Stephanie Mary. "Production of astaxanthin by the yeast Phaffia rhodozyma." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324833.
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Rydevik, Magnus. "Smoltification and early sexual maturation in the Baltic salmon, Salmo salar L." Stockholm : Niversity of Stockholm, 1989. http://catalog.hathitrust.org/api/volumes/oclc/21828246.html.
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Zhou, Shengying. "Function of muscle adipocytes in Atlantic salmon, Salmo salar, exposed to hydrocarbons." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ31538.pdf.
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Rivinoja, Peter. "Migration problems of Atlantic salmon (Salmo salar L.) in flow regulated rivers /." Umeå : Dept. of Aquaculture, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005114.pdf.
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Vasemägi, Anti. "Evolutionary genetics of Atlantic salmon (Salmo salar L.) : molecular markers and applications /." Umeå : Dept. of Aquaculture, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s324.pdf.
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Counter, Sarah-Louise. "The sustainability of Atlantic salmon (Salmo salar L.) in South West England." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/8203.
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Conservation studies have generally focused on the environmental and biological issues affecting the decline of a species. However, to ensure the sustainability of a species three aspects must be considered: biological, economic and sociological. This thesis focuses on a case study of salmon in the Exe catchment comprising three individual studies, and explores the temporal stability of the species across the South West region to assess the status of salmon in other catchments within the region. A panel of microsatellite markers modified from the West Virginia panel was utilised in exploring the population genetics of Atlantic salmon. Weak population structuring was found within the Exe supported by a number of population genetic statistics. This information was provided to hatchery managers who modified their protocols utilising two strains of fish rather than stocking the catchment with fish from only one tributary. The catchment level estimate of effective population size was consistently reported to be lower than the management target (MT). A questionnaire distributed to more than 200 anglers suggested that despite a wide variation in opinion the consensus was that as a group they are happy with current management practices but that there are still some changes that could be made, for example, many respondents felt that the some groups involved in decision making regarding salmon management should have a different level of input than they currently have. The majority of anglers were positive about the use of hatcheries as a management tool. The efficacy of practices at two South West hatcheries (Exe and Tamar) was assessed. Both hatcheries suffered from a decreased level of genetic diversity as a result of the use of a small number of adults and a bias in parental contribution. Finally, a spatio-temporal analysis of the region suggested that spatial distribution is a dominant force to temporal variation in shaping the population structure of Atlantic salmon in the region. A distinct divide was observed between populations of salmon in the easterly chalkstream rivers (e.g. the Test, Itchen and Frome) and those in the west of the region (e.g. the Exe, Taw and Fowey). The findings of these studies are discussed in a wider context and support the following recommendations: 1. If a hatchery is to be used on the Exe catchment multiple stocks should be reared to reflect the populations found. 2. Stakeholders, including representatives of angling groups should be involved in conservation and kept up to date with research undertaken and results found. 3. If the Exe and Tamar hatcheries are to be continued, more broodstock should be utilised to improve levels of genetic diversity in the offspring. 4. Effective population size should continue to be monitored at a number of key sites across the region. These sites should be selected following more in depth studies of population structure at a catchment level.
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Bale, Claire. "Acid episodes and the behavioural ecology of Atlantic salmon, Salmo salar L." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54634/.
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Although the impacts of surface water acidification on Atlantic salmon (<italic>Salmo salar</italic> L.) and brown trout (<italic>Salmo trutta</italic> L.) are well described, factors affecting recovery following pollution abatement are poorly understood. Paradoxically, despite increasing average pH over the last two decades, stocking efforts to rehabilitate damaged populations have not been successful. One possible explanation is that average pH measurements mask the effects of episodic fluctuations during high flow when pH is transiently reduced, metal concentrations are elevated and some organisms are affected adversely. However, because salmonid fish (i) avoid acid water and (ii) shelter within stream bed interstices, assessing the effects of acid episodes on their populations requires some understanding of how refuge use, refuge availability and refuge conditions affect recolonisation opportunities. This project therefore examined the effects of acid episodes on the behaviour of Atlantic salmon at different life stages as a possible explanation for the limited recovery of re-stocked populations. Sampling in acid sensitive-streams at low and high (episodic) flow revealed that the stream hyporheos was less acid than surface water in the same streams, with temperature and conductivity also more favourable in interstices. Laboratory experiments were then used to examine (i) the behaviour of Atlantic salmon alevins during a simulated episode in a vertical substrate-filled tank (Chapter 3) (ii) the behaviour of Atlantic salmon parr during a simulated episode in a shelter choice tank (Chapter 4) and (iii) if differences resulting from rearing environment affected the behaviour of Atlantic salmon parr during a simulated acid episode (Chapter 5). Hatchery-reared alevins avoided episodically acid conditions by moving into an area of more neutral pH opercular rate and mortality were both greater in acid water. Hatchery-reared pan- preferentially used a neutral shelter acid exposure also resulted in increased activity and opercular rate. Fish reared in a simulated wild environment were better able to avoid acid pulses (i.e. they showed greater use of neutral refuges) than hatchery-reared fish, but other behavioural responses (activity and opercular rate) were similar. These results illustrate the potential importance of the streambed during acid episodes as chemical refuges to salmonids, which both alevins and parr are able to exploit. However, at least for hatchery-reared fish, the success of re-stocking programmes could be improved by subjecting fish to acid stress- conditioning regimes prior to release.
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Williams, Keith. "Nutrient transportation associated with the migrations of Atlantic salmon (Salmo salar L.)." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55728/.
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Nutrients are essential in order that living matter can grow and reproduce successfully, and of particular importance are carbon (C), nitrogen (N) and phosphorus (P) (Stockner and Ashley 2003). C and N have a gas phase and are often readily available in freshwater ecosystems. P, however, does not have a gas phase, cannot be renewed and as such is often regarded as the element in shortest supply in most freshwater environments (Stockner and Ashley 2003). It should be noted, though, that other nutrients, for example silica, are also often of importance in freshwater ecosystems and that nutrients can be co-limiting in terms of primary production (Toetz 1999).
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Leksell, Lina. "Early environmental effects on dominance in juvenile Atlantic salmon (Salmo salar L.)." Thesis, Karlstads universitet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-55304.
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The earth’s climate is rapidly changing. With climate change currently altering the environment, water temperature is an important environmental factor that will have various effects on fishes since they are ectotherms. As the changes are expected to be greatest during winter, when salmonid fishes incubate their eggs, one might expect substantial effects on egg development. In this experiment pairs of fish, matched by length, were compared. For each pair, one fish had experienced ambient cold temperatures (cold treatment) during embryogenesis and the other elevated temperatures (warm treatment, ca. 4-5 oC). The fish were tested in stream. Aggressive interactions were recorded and dominance was determined by scoring each fish’s position relative to where food was delivered from and the amount of food taken. Salmon from the cold treatment had a strong tendency to have a higher dominance score than salmon from the warm treatment. The individual with the highest dominance score was not consistently larger or smaller than the individual with the lower dominance score. The results support the hypothesis that salmonids exposed to a cold environment during embryogenesis will be more dominant. Due to climate change, it is expected that water temperature will continue to rise in the future, which in turn will alter the fish’s behaviour.<br>Jordens klimat förändras snabbt. Med klimatförändringar som för närvarande förändrar miljön är vattentemperaturen en viktig miljöfaktor som kommer att ha olika effekter på fiskar eftersom de är ektoterma. Eftersom förändringarna förväntas vara störst under vintern, när laxfiskar inkuberar sina ägg, kan man förvänta sig betydande effekter på äggutvecklingen. I det här experimentet jämfördes fisk par, matchade med längd. För varje par hade en fisk upplevt kalla vattentemperaturer (kall behandling) under embryogenesen och de andra förhöjda temperaturerna (varm behandling, ca 4-5 oC). Fisken testades i strömakvarie. Aggressiva interaktioner registrerades och dominans bestämdes genom att poängsätta varje fisks position i förhållande till var mat levererades från och mängden mat som tagits. Lax från den kalla behandlingen hade en stark tendens att ha högre dominanspoäng än lax från den varma behandlingen. Individen med högsta dominanspoäng var inte konsekvent större eller mindre än individen med lägre dominanspoäng. Resultaten stöder hypotesen att salmonider utsätts för en kall miljö under embryogenes kommer att vara den mer dominerande. På grund av klimatförändringen är det förväntat att vattentemperaturen fortsätter att stiga i framtiden, vilket i sin tur kommer att förändra fiskens beteende.
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Wang, Junwen. "Optimization and modeling of enzymatic hydrolysis of Atlantic salmon (Salmo salar) tissue /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5307.
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Butler, Ricky. "In vitro modelling of the immunological interactions between the salmon louse, Lepeophtheirus salmonis (Kroyer, 1837), and the Atlantic salmon, Salmo salar (L., 1758)." Thesis, University of Stirling, 2001. http://hdl.handle.net/1893/21841.
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Atlantic salmon, SaI1M salar. L., have been shown to be more susceptible to infections by the caligid copepod Lepeophtheirus salmonis (Kreyer, 1837) than other salmonid species. Atlantic salmon exhibit a reduced cellular immune response to the attached parasite which has led to the hypothesis of the presence of sea louse associated compounds that depressed the fish's normally efficient inflammatory mechanisms. The aim of the current study was to test this hypothesis. A biochemically defmed in vitro culture system was developed that would allow collection of the secreted/excreted products of the copepodid larvae of L. salmonis, and avoid their contamination by metabolites of the host from their collection, in vivo. Available tissue culture methods proved inadequate in supporting copepodid culture because of the louse requirement for a seawater maintenance medium that was osmotically unsuitable for cultured cells. Tissue engineering technologies developed in the construction of human living skin equivalents were successful in the development of an Atlantic Salmon Skin Equivalent (ASSE). ASSE is a novel organotypic tissue culture substrate that was constructed from Atlantic salmon fibroblasts (AS-6) and primary cultures of Atlantic salmon epithelial cells. Cells were supported in a matrix of collagen fibres, acid extracted from the tails of rats, and combined using a layering technique to create a substitute salmon skin. ASSE has a fibroblastic dermal equivalent overlaid by an epidermis-like layer and a layer of collagen, and was maintainable in a seawater media. During its development, the cells within ASSE showed signs of differentiation that included stratification, increased fibronectin production by cultured fibroblasts, and the formation of a basement membrane-like layer at the junction of the dermis and epidermis. In this environment, ASSE allowed the survival of copepodid larvae for an average of 12 days, a period approximately 5 days longer than that of their free-swimming counterparts. Furthermore, cultured copepodids were observed feeding, exhibiting the normal range of settlement behaviours, and also showed increases in their length. However, metamorphosis to the chalimus I stage did not occur and was not stimulated by the supplementation of ASSE with salmon mucus, salmon peptone or DL methionine. Nevertheless, copepodid maintenance on ASSE allowed the collection of the compounds they released into the culture media. These were assayed for their effects on the immunological functioning of salmon macrophages. These assays demonstrated that the chemotaxic ability of macrophages was significantly reduced following treatment with louse culture supernatants . (LCS), as was their phagocytic ability. In both assays, the activity of each function was approximately 50% lower than that recorded in untreated cells. Intracellular respiratory burst and the phagocytic index of active phagocytes, however, was not affected. The biological activity of LCS was inhibited following heating, dilution, and treatment with proteinase K, indicating that the active immunosuppressive compounds were either themselves proteins, or required protein to be effective. The active substance was designated Louse Immunomodulatory Factor (LIF). The enzyme profiles of culture supernatants were investigated using API ZYM test strips. The profiles of LCS supernatants were significantly different to those of control supernatants from the early stages of louse incubation with ASSE. LCS supernatants showed elevated levels of leucine aminopeptidase, C4 and C8 esterases, alkaline phosphatase, P-glucuronidase, and Nacetyl- j-glucosaminidase. The involvement of these enzymes in the digestive processes of arthropods is well documented. However, the presence of the chitin hydrolysing enzyme Nacetyl- Beglucosaminidase, may also be suggestive of the preparation of copepodids for moulting. This, and the involvement of these enzymes in digestion in copepodids, and as possible immunomodulatory compounds is discussed. Gel filtration chromatography identified 14 proteins in the LCS that were not present in the control supernatants. These proteins were in the molecular weight range <1 kOa to 2665 kOa. No biological activity was attributed to these proteins when isolated by chromatography and assayed for their effects on macrophage chemotaxis. This lack of activity may be associated with their dilution during the chromatography process in which the supernatants were diluted approximately 5000 times. Experimental evidence showed that the activity of LIF was absent when supernatants were diluted to 1:1000, and so methods of concentration may be required in order to establish the immunological activity of these proteins. This study has developed an Atlantic salmon skin substitute that could have a great number of applications in the study of salmonid metabolism, cellular communication, immunology, and drug and chemical testing. Here, it supported the extended maintenance of sea lice larvae in vitro and allowed the collection of the products of their culture. The findings have shown that the copepodid stage of L. salmonis produces substances, LIF, that depress the chemotaxic and phagocytic activity of salmon macrophages, in vitro. These active substances may also be responsible for the depression of the inflammatory responses of sea lice infected Atlantic salmon, in vivo.
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Herath, Tharangani K. "Cellular and molecular pathogenesis of Salmonid alphavirus 1 in Atlantic salmon Salmo salar L." Thesis, University of Stirling, 2010. http://hdl.handle.net/1893/2325.
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Salmonid alphaviruses (SAV) are a group of viruses that have recently emerged as a serious threat to the salmonid aquaculture industry in Europe. Over recent years, diseases caused by SAV have severely hampered the Scottish, Irish and Norwegian Atlantic salmon industry, and are considered to be among the major economically important viral diseases affecting the industry at present. Amongst the six subtypes characterised so far, Salmonid alphavirus 1 (SAV1) causes severe pathology in the heart, pancreas and the skeletal muscle of Atlantic salmon leading to death and growth retardation in the affected fish. The biochemical characteristics of the virus and the sequential pathology of the diseases caused by SAV have been described; however the mechanisms responsible for causing the disease and the host defence mechanisms against the virus are poorly defined. This thesis therefore examined the pathogenesis of SAV infection at the cellular and molecular level in vivo in salmon and in vitro in salmonid cells, with a special emphasis on host immune defence mechanisms against the virus. SAV was first isolated from Chinook salmon embryo-214 (CHSE-214) cells in 1995 in Ireland. Several cell lines have since been used to grow the virus. In the present study, three established salmonid cell lines, Chum salmon heart -1 (CHH-1), CHSE-214 and Salmon head kidney -1 (SHK-1) were evaluated for their ability to support the isolation of SAV-1 from infected fish tissue, with CHH-1 cells giving the fastest cytopathic effect (CPE) during primary isolation. The CPE appeared as localised cell-rounding on CHH-1 and CHSE-214 cells, although in SHK-1 cells, the cells were seen to slough off the monolayer relatively later than with the other two cell lines during the infection. The host response to SAV infection was evaluated by experimentally infecting Atlantic salmon parr using a cell culture-adapted virus isolate. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) was developed to examine the virus load in the fish, from which it was found that the highest viral RNA copy number was detected at 5 day post infection (d.p.i), of the 90 day experimental infection period. Characteristic pathological lesions were only seen in the pancreas and the heart but not in the skeletal muscles of the infected fish. A gene expression study using qRT-PCR revealed the rapid induction of interferon (INF) and INF-associated genes in the head kidney of the infected fish compared to the control fish. The Mx protein was found to be highly expressed in the heart and the mucous membranes of infected fish by immunohistochemistry. Interestingly, the pathological changes that were seen occurred some time after the peak expression of genes associated with the INF-1-pathway. When the host-virus interaction of Atlantic salmon infected with SAV was examined using a microarray, a potent first line defence response was observed, together with the signatures of early activation of the adaptive immune response during the initial stages of the infection. Genes associated with transcription, translation and lipid metabolism were significantly differentially expressed in virus infected fish compared to control fish. A large array of antiviral genes was significantly expressed, amongst which were some of the genes also described in mammalian alphavirus infections. Genes associated with apoptosis and anti-apoptosis were also seen to be differentially regulated showing the complexity of the host-virus interaction. Collectively, all of these findings suggest that a non-specific antiviral immune response takes place providing rapid immune protection during the early stages of SAV infection in salmon. In the study on morphogenesis of SAV in salmonid cells using electron microscopy (EM), a rapid internalization of virus into the cells and generation of replication complexes using the secretory pathway of the cell, similar to mammalian alphavirus replication was observed. The mature viruses were released through surface projections, acquiring envelopes from the host cell membrane. From the ultrastructural studies of the salmonid cells infected with SAV, a progressive chromatin marginalisation and condensation could be seen, leading to cellular fragmentation, forming membrane bound apoptotic bodies, characteristic of progressive apoptosis. The activation of caspase-3 in the cytoplasm and genomic DNA damage were also seen in the infected fish cells, indicating that apoptosis is the main cause of cell death during SAV infection. The results of this study have increased our knowledge and understanding of the cellular and molecular mechanisms involved in the pathogenesis of SAV infection, emphasising the importance of the first line defence mechanisms against SAV infection in salmon. This has given an interesting insight into the host mechanisms used to combat the virus during infection, and will undoubtedly be useful for designing new vaccines and management strategies for prevention and control of this important disease
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Barbour, Andrew J. S. "The transition of adult Atlantic salmon (Salmo salar L.) from saltwater to freshwater." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU362766.
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Aspects of the behaviour of adult Atlantic salmon in estuaries, while on their spawning migration has been investigated using a salinity telemetric system. Eighteen fish were tracked in total in different Scottish estuaries. Studies involving the displacement of salmon from freshwater back into higher salinities on the River North Esk, Montrose showed fast movement through the estuary back into freshwater (5h), movement being initiated by the sensing of low salinities or the start of the flood tide. Tracking in the Dornoch Firth at Bonar Bridge (a channel type estuary) showed fish maintaining one position against both flood and ebb tides, experiencing salinities fluctuating widely about the isosmotic point. The qualitative assessment of salmon on passage through the estuary of the freshwater discharge of a non-natal river was also demonstrated, repeated entries of a very brief nature (21s) being recorded. The position held by salmon whilst on suspended migration in an estuary was recorded, no sampling of the freshwater discharge being undertaken on a tidal basis. The resting metabolic rate of farmed salmon of different stages of sexual development was recorded in saltwater, and on transfer to freshwater. Maturing fish exhibited a raised metabolic rate in saltwater, suggesting increased osmoregulatory costs. This was in contrast to non-maturing fish. The cannulation of wild salmon subjected to fluctuating salinities was undertaken. Plasma electrolyte levels and osmolalities of fish subjected to cyclic salinities were intermediate between salt-adapted and freshwater-adapted values, showing only small fluctuations. An inability to osmoregulate successfully in high salinities following 'stress' events was recorded in maturing farmed and coastally caught wild salmon, suggesting a maladaption to that environment. By contrast, non-maturing farmed salmon exhibited a greater degree of euryhalinity. Examination by electron scanning microscopy of apical pit structure of gill chloride cells supports the idea that increasing maturity or freshwater exposure reduces tolerance to saltwater. It is concluded that Atlantic salmon are euryhaline during at least part of their oceanic feeding phase, and on arrival in coastal waters on the spawning migration require no period of acclimitisation to freshwater. A reduction in tolerance to high salinities linked to advancing maturation/ freshwater exposure would thus serve to ensure river entry.
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Tang, Stephen. "Assessing the welfare of adult Atlantic salmon, Salmo salar during commercial live-haul transport." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/512.
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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.
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Dehler, Carola. "The intestinal microbes of Atlantic salmon (Salmo salar) : implications for gut health and nutrition." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231927.
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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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Cross, Alison Danielle. "Early marine growth and consumption demand of juvenile pink salmon in Prince William Sound and the northern coastal Gulf of Alaska /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5314.
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Steel, E. Ashley. "In-stream factors affecting juvenile chinook salmon migration /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/6371.
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Hamon, Troy R. "The role of natural and sexual selection in local adaptation of spawning behavior and morphology in sockeye salmon, Oncorhynchus nerka /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5379.
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Berrill, Iain Kevin. "Environmental influences on growth, maturation and smoltification in Atlantic salmon parr, Salmo salar." Thesis, University of Stirling, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720353.
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Hammond, Gregory Elliott. "Genetic variability and population differentiation in Atlantic salmon (Salmo salar) from New Brunswick." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ57292.pdf.
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Côté, Michelle. "Isolation and charaterization of the carotenoid-binding protein in Atlantic salmon (Salmo salar)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0029/MQ63497.pdf.
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Simard, Nathalie C. "Development of a DNA vaccine against Renibacterium salmoninarum in Atlantic salmon (Salmo salar)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0031/MQ65519.pdf.
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Eriksson, Torleif. "Migratory behaviour of Baltic salmon (Salmo salar L.) : adaptive significance of annual cycles." Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 1988. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100715.
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This thesis evaluates the adaptive significance of annual cycles on the migratory behaviour of Baltic salmon (Salmo salar L.). The studies have included field experiments as well as laboratory studies gf maturity and migratory behaviour patterns of smolts and postsmolts mainly from the Angerman river population. Contrasting to the phenotypical elasticity in life-history traits, Baltic salmon was found to have a rather strict temporal organization of their annual behavioural patterns. Two year old smolted Baltic salmon showed drastic differences in migratory behaviour when compared in tanks containing either fresh or brackish water. Freshwater kept fish showed an annual cycle where downstream displacement in the upper water column was followed by a stationary behaviour, indicating a readaption to a freshwater life. Fish in brackish water behaved as a migratory fish throughout tne study. Baltic salmon also showed differences in maturation patterns in fresh and brackish water. Three summer old males detained in freshwater all matured sexually the following autumn. If transferred to sea and kept in net- pens a low proportion matured, mainly previously matured males. Furthermore there was a size- dependent relationship of sexual rematuration. Many small previously matured males did not migrate, similarly small previolusly matured males were unable to respond to shifts in the environment. With larger size the alternatives of sexual maturation and high growth rate wi more related to the environmental conditions the fish experienced. A hypothesis has been tested assuming that Baltic salmon migration is influenced by an annual time program. According to the hypothesis the migratory distance covered in the Baltic should be a result of a migratory activity sequence rather than a definite goal orientation. Fish detained before release generally showed a shorter distance between release point and area of recapture compared to fish released at normal time of smoltrun. The migratory distance appeared to be inversly related to the period of delay before release. A seasonal difference in migratory propensity was recorded. An instantaneous mortality curve for Baltic salmon during seaward migration and early sea-phase was estimated based on recapture data on sequentially related fish. The weekly mortality rate decreased from an initial mean of 271 during onset of migration, to 3.51 in mean during autumn. The high risk of mortality during the first part of migration indicated that strong selective forces act on a precise seasonal timing of migration.<br><p>Diss. (sammanfattning) Umeå : Umeå universitet, 1988, härtill 5 uppsatser</p><br>digitalisering@umu
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Finn, Fia. "Risk taking and downstream migration in hatchery reared Atlantic salmon (Salmo salar) smolt." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-108496.
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Individual variation and limited plasticity in behavior are factors that have been shown to shape populations and determine how well individuals are doing in different stages of life. When salmon transform from parr to smolt and start the migration out to sea many factors together make an individual successful. The hypothesis of this study was that the boldness of individual smolt (1 and 2 year olds) is correlated to their inclination to migrate downstream. The study also investigated difference in boldness and migration tendency between 1- and two year old smolt. Today, some hatcheries release smolt as both one and two year old and it is important to know whether there is any difference in behavior and migration intensity between age classes in order to make stocking programs more effective. To determine if the individuals differed in boldness, and/or displayed a bold behavioral type, two assays were performed in different contexts (novel environment and simulated predatory attack). Downstream migratory intensity was, after behavior assays, quantified in an artificial stream. I found that: i) the one year old smolts tended to be bolder in a predatory response assay than two year old smolt, ii) one year old smolts migrated less in the artificial stream compared to two year old smolt. Being bolder can have an effect on several aspects connected to fitness in the salmon life cycle and could affect the survival of a smolt migrating out to sea, even though no correlations to inclination to downstream migration were found in this study.
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Simpson, Anna L. "Investigation of the factors influencing maturation in Atlantic salmon, Salmo salar L., parr." Thesis, University of Glasgow, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390441.
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Plant, Karen Patricia. "Studies on resistance to infectious pancreatic necrosis virus in Atlantic salmon (Salmo salar)." Thesis, University of Stirling, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365033.
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Gorman, Catherine. "Assessing the performance of captive bred Atlantic salmon, Salmo salar, in wild populations." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676480.
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The impact of Atlantic salmon S. salar farm escapes/intentional releases of non-native salmon and stocking of fertile farm/hatchery reared individuals on the genetic integrity, fitness and long-term viability of wild populations has been the focus of considerable debate. In this study, the consequences of both a S. salar supplemental stocking programme and the long-term consequences of farm escapes are assessed. AS. salar supplemental stocking programme was established in 1996 in the River Bush, Northern Ireland, in an effort to increase the diminishing adult returns. Capitalising on this programme, in this study, 40 wild males and 40 wild females were selected as broodstock. Eggs were stripped from females and fertilized in vitro to produce 40 unique families. Resulting eggs were reared under hatchery conditions. ~90,500 un-fed fry were stocked into areas with limited spawning potential. >2,400 smolts were intercepted and genotyped for a suite of microsatellite markers and assigned to the parental broodstock. Analysis revealed that the overall percentage survival of the stocked hatchery-reared fish was 0.66%. Results are considered in terms of costs (e.g. potential genetic consequences related to mate choice) & benefits (e.g. increased production). In two classic studies, Clifford et al. (1998a, 1998b) investigated large S. salar escapes, involving adult and juvenile individuals, and their impacts on wild populations. Based on their findings the authors demonstrated that only a small proportion of adult escapes managed to successfully breed in the wild. They have also suggested that escaped juvenile farm salmon can potentially complete their life cycle, breed and interbreed with native fish upon their return to the river. In the current study, the sites of Clifford's studies were revisited 20 years later. New samples were collected and screened alongside the samples used in Clifford's studies, as well as additional samples not screened at the time. In total over 3,000 S. salar were screened for 25 microsatellites and one mitochondrial DNA marker, known to be associated with farmed fish. Results of analyses confirm limited impact of adult salmon escapes on wild populations and provide good evidence for the establishment of a farm derived population in the wild.
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Guy, Derrick Richard. "Genetic resistance to infectious pancreatic necrosis virus in pedigreed atlantic salmon (Salmo salar)." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5293.
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Infectious Pancreatic Necrosis (IPN), due to infection with the IPN virus (IPNv), continues to cause heavy mortalities and is endemic across the major Atlantic salmon farming regions of the world. Prevalances of 0.3-0.8 or more at the freshwater stage and 0.05 to 0.3 in the seawater phase of production are typical. Partially effective injectable vaccines are available against seawater IPN but biosecurity measures remain the main methods of control. To explore the feasibility of selecting salmon for resistance to IPN, a selective breeding program was initiated in 1996, including a series of field and experimental trials challenging known full-sib families with IPNv. A total of 404,723 fish faced IPNv challenge (376,541 seawater and 28,182 freshwater) covering 14 years and 17 separate locations across 7 sites. Mortalities and survivors following IPN challenge were counted by full-sib family and analysed as binomial data (alive / dead). Initial heritabilities were obtained from expressions based on the variance and covariance of full-sib family means for the 2001 year-group, indicating heritabilities (h2) of 0.16, range 0.08 to 0.24, and genetic correlations (rg) between replicate families of 0.71 to 0.78. These results were then confirmed by residual maximum likelihood across all seawater challenged data (year-groups 1997-2003), indicating a h2 of 0.43 (s.e.0.02) across all sites, range 0.06 to 0.40 for individual sites, and a range of rg between replicates of 0.70 to 0.87 (s.e. approx 0.05). To accommodate datasets and pedigrees approaching half a million individually identified fish, an implementation of the Reduced Animal model (RAM) was used to obtain these estimates. A similar level of genetic variation for resistance to freshwater IPN (year-groups 2005-2009) was confirmed with a h2 of 0.49, (s.e. 0.03), range 0.31 to 0.59, and rg between replicates ( 0.80 to 0.95, s.e. approx 0.05), using an Individual Animal Model. When all the data were analysed together, assuming seawater and freshwater survival to be the same trait, the heritability increased to 0.67, (s.e. 0.02). On testing this assumption, the genetic correlation between freshwater and seawater survival was found to be 0.68 s.e. 0.09. Both these pooled estimates account better than those for the individual site estimates, for the known selection of superior families that was incorporated at the earliest opportunity (2001) into the selective breeding program. To further investigate if there were favourable or antagonistic relationships operating between traits under active selection, genetic correlations between IPN mortality and a range of performance and harvest traits were obtained. When restricting the harvest data to year-groups where the harvested fish had not experienced an IPN event (2003 for seawater IPN, 2005 for freshwater IPN) : fish length and flesh colour just reached significance with seawater IPN (0.27 to 0.53. s.e. 0.14), while only harvest weight (0.30 s.e 0.11) attained significance with freshwater IPN mortality. All these correlations were antagonistic. When all the data were combined, (ie both IPN and harvest events taken from all yeargroups) these became non-significant. Taken as a whole, these results indicate that selecting salmon for resistance to both seawater and freshwater IPN challenge certainly is feasible, and that adverse effects on selection for other important production traits is not expected. How these medium to high heritabilities relate to the discovery of a major QTL for IPN resistance segregating in these populations, reported in a parallel scheme of work but based on a sub-set of the same families, is discussed.
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Clokie, Benjamin Gregory James. "Impact of lighting conditions on the developmental physiology of Atlantic salmon (Salmo salar)." Thesis, University of Stirling, 2017. http://hdl.handle.net/1893/27240.
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The Atlantic salmon (Salmo salar) lifecycle is punctuated by distinct ontogenic stages which are routinely manipulated commercially by photoperiod regimes to enable year-round production. As such, light plays a critical role throughout the production cycle, however, it remains poorly characterised and light spectrum and intensity have not been defined optimally yet. This thesis was therefore set out to test the effects of narrow bandwidth light (Blue-λ(max) 444 nm, Green-λ(max) 523 nm, Red-λ(max) 632 nm and White) and intensity in freshwater (FW). Fry-parr development, out-of-season smoltification and ocular and vertebral health were examined as was the long-term effects of FW light regimes on seawater (SW) growth and muscle structure. In addition, the impact of photoperiod regimes on out-of-season smolts following transfer to SW was investigated. 
 Major findings from the trials conducted show that light spectrum and intensity influence parr development with lower intensities performing better than higher intensities. Both the initiation and duration of smoltification was impacted by spectrum. Importantly, this doctoral work showed that daily changes in light intensity, from low during the scotophase to high during the photophase applied for the duration of a standard out-of-season smoltification regime was capable of providing a sufficient cue for the induction of smoltification. Historic FW light exposure impacted SW performance and post-transfer SW photoperiod had significant impact upon growth and maturation development. Results based on changes to the gonadosomatic index provide important guidance for suitable post-transfer photoperiods for smolt transferred to SW around the winter solstice. Importantly, from the parameters tested, exposure to different spectrum or light intensities did not adversely affect vertebral or ocular health. 
 This thesis did not only focus on the physiological effects of light but also aimed to characterise better the pathways involved in light perception and integration. To do so, the neural response to both broad spectrum white light, darkness and Red and Blue light was investigated through deep brain insitu-hybridisation and high throughput sequencing (NGS) of the pituitary gland. Results showed substantial spectral and light/dark changes in the both the deep brain and pituitary transcriptome. Overall, this research provides both scientifically interesting and commercially relevant guidance for the optimisation of lighting systems for use in captive salmon aquaculture. Major findings from the trials conducted show that light spectrum and intensity influence parr development with lower intensities performing better than higher intensities. Both the initiation and duration of smoltification was impacted by spectrum. Importantly, this doctoral work showed that daily changes in light intensity, from low during the scotophase to high during the photophase applied for the duration of a standard out-of-season smoltification regime was capable of providing a sufficient cue for the induction of smoltification. Historic FW light exposure impacted SW performance and post-transfer SW photoperiod had significant impact upon growth and maturation development. Results based on changes to the gonadosomatic index provide important guidance for suitable post-transfer photoperiods for smolt transferred to SW around the winter solstice. Importantly, from the parameters tested, exposure to different spectrum or light intensities did not adversely affect vertebral or ocular health. This thesis did not only focus on the physiological effects of light but also aimed to characterise better the pathways involved in light perception and integration. To do so, the neural response to both broad spectrum white light, darkness and Red and Blue light was investigated through deep brain insitu-hybridisation and high throughput sequencing (NGS) of the pituitary gland. Results showed substantial spectral and light/ dark changes in the both the deep brain and pituitary transcriptome. Overall, this research provides both scientifically interesting and commercially relevant guidance for the optimisation of lighting systems for use in captive salmon aquaculture.
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Rawlings, Claire E. "Rhythmic stomach fullness in Atlantic salmon (Salmo salar L.) and the influencing variables." Thesis, University of Stirling, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261731.
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Roy, William J. "Vitamin E nutrition and pancreas disease in farmed Atlantic salmon (Salmo salar L.)." Thesis, University of Stirling, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294027.
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Turnbull, James F. "Studies on dorsal fin rot in farmed Atlantic salmon (Salmo salar L.) parr." Thesis, University of Stirling, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317643.
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