Literatura académica sobre el tema "Sea lice; Salmon farms"
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Artículos de revistas sobre el tema "Sea lice; Salmon farms"
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Morton, Alexandra, Richard Routledge, Corey Peet y Aleria Ladwig. "Sea lice (Lepeophtheirus salmonis) infection rates on juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon in the nearshore marine environment of British Columbia, Canada". Canadian Journal of Fisheries and Aquatic Sciences 61, n.º 2 (1 de febrero de 2004): 147–57. http://dx.doi.org/10.1139/f04-016.
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This study compared sea lice (Lepeophtheirus salmonis) infestation rates on juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon in five nearshore areas of the British Columbia coast selected on the basis of proximity to salmon farms. A 10-week study in the Broughton Archipelago found sea lice were 8.8 times more abundant on wild fish near farms holding adult salmon and 5.0 times more abundant on wild fish near farms holding smolts than in areas distant from salmon farms. We found that 90% of juvenile pink and chum salmon sampled near salmon farms in the Broughton Archipelago were infected with more than 1.6 lice·(g host mass)1, a proposed lethal limit when the lice reach mobile stages. Sea lice abundance was near zero in all areas without salmon farms. Salinity and temperature differences could not account for the higher infestation rates near the fish farms. The most immature life stages dominated the lice population throughout the study, suggesting the source of lice was a stationary, local salmonid population. No such wild population could be identified. The evidence from this controlimpact study points to a relationship between salmon farms and sea lice on adjacent, wild, juvenile salmon.
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Middlemas, S. J., J. A. Raffell, D. W. Hay, M. Hatton-Ellis y J. D. Armstrong. "Temporal and spatial patterns of sea lice levels on sea trout in western Scotland in relation to fish farm production cycles". Biology Letters 6, n.º 4 (17 de febrero de 2010): 548–51. http://dx.doi.org/10.1098/rsbl.2009.0872.
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The relationship between aquaculture and infestations of sea lice on wild sea trout ( Salmo trutta ) populations is controversial. Although some authors have concluded that there is a link between aquaculture and lice burdens on wild fish, others have questioned this interpretation. Lice levels have been shown to be generally higher on Atlantic salmon farms during the second years of two-year production cycles. Here we investigate whether this pattern relates to lice burdens on wild fish across broad temporal and spatial axes. Within Loch Shieldaig across five successive farm cycles from 2000 to 2009, the percentage of sea trout with lice, and those above a critical level, were significantly higher in the second year of a two-year production cycle. These patterns were mirrored in 2002–2003 across the Scottish west coast. The results suggest a link between Atlantic salmon farms and sea lice burdens on sea trout in the west of Scotland.
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Morton, Alexandra B. y Rob Williams. "First Report of a Sea Louse, Lepeophtheirus salmonis, Infestation on Juvenile Pink Salmon, Oncorhynchus gorbuscha, in Nearshore Habitat". Canadian Field-Naturalist 117, n.º 4 (1 de octubre de 2003): 634. http://dx.doi.org/10.22621/cfn.v117i4.834.
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High infestation rates of the Sea Louse (Lepeophtheirus salmonis) have been reported on juvenile salmonids in Europe since 1989; however, this species has not been reported on juvenile Pacific salmonids until now. Magnitude of Sea Lice infestation was examined in 2001 on juvenile Pink Salmon (Oncorhynchus gorbuscha) migrating through a British Columbia archipelago. On average, the 751 juvenile Pink Salmon sampled weighed 2.25 g (± 0.039 SE), were infected with 11.3 (± 0.41 SE) Sea Lice per fish and 6.1 (± 0.24SE) Sea Lice per gram host weight. Fully 75.0% of fish were infected at loads equivalent to or higher than the lethal limit reported for much larger Sea Trout (Salmo trutta) post-smolts. Abundance (Kruskal-Wallis statistic = 100.95, p<0.0001) and intensity (KW= 70.05, p<0.0001) of lice, and mean number of lice/g host weight (K-W= 112.23, p<0.0001) were significantly higher in juvenile Pink Salmon in close proximity to salmon farms, than in Pink Salmon distant from salmon farms.
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Morton, Alexandra, Rick Routledge, Amy McConnell y Martin Krkošek. "Sea lice dispersion and salmon survival in relation to salmon farm activity in the Broughton Archipelago". ICES Journal of Marine Science 68, n.º 1 (11 de octubre de 2010): 144–56. http://dx.doi.org/10.1093/icesjms/fsq146.
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Abstract Morton, A., Routledge, R., McConnell, A., and Krkošek, M. 2011. Sea lice dispersion and salmon survival in relation to salmon farm activity in the Broughton Archipelago. – ICES Journal of Marine Science, 68: 144–156. The risk of salmon lice (Lepeophtheirus salmonis) transmission to wild juvenile Pacific salmon has spurred management change to reduce lice on salmon farms. We studied the abundance of planktonic lice preceding the juvenile salmon outmigration as well as the abundance of lice on juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon in two distinct migration routes, one containing only fallow farms and the other active farms that applied a parasiticide. Results indicate that fallowing reduces the abundance and flattens the spatial distribution of lice relative to that expected in areas without farms. Active farms remained the primary source of lice, but transmission was reduced 100-fold relative to previous epizootics in the study area. On the migration route containing active farms, ∼50% of the juvenile salmon showed evidence of louse damage to surface tissues and the estimated direct louse-induced mortality was <10%, not including indirect effects of infection on predation risk or competition. The survival of the pink salmon cohort was not statistically different from a reference region without salmon farms. Although repeated use of a single parasiticide can lead to resistance, reducing louse transmission from farmed salmon may help conserve some wild Pacific salmon populations.
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Peacock, Stephanie J., Martin Krkošek, Andrew W. Bateman y Mark A. Lewis. "Estimation of spatiotemporal transmission dynamics and analysis of management scenarios for sea lice of farmed and wild salmon". Canadian Journal of Fisheries and Aquatic Sciences 77, n.º 1 (enero de 2020): 55–68. http://dx.doi.org/10.1139/cjfas-2019-0036.
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Parasite transmission between farmed and wild salmon affects the sustainability of salmon aquaculture in Pacific Canada. Understanding and managing parasites in aquaculture is challenged by spatial and temporal variation in transmission dynamics. We developed a mechanistic model that connects sea louse (Lepeoptheirus salmonis) outbreak and control on farmed salmon (Salmo salar) to spatiotemporal dynamics of sea lice on migrating wild juvenile salmon (Oncorhynchus keta and Oncorhynchus gorbuscha). We fitted the model to time series of sea lice on farmed salmon and spatial surveys of juvenile wild salmon in the Broughton Archipelago. We used the parameterized model to evaluate alternative management scenarios based on the resulting sea louse infestations and predicted mortality of wild salmon. Early and coordinated management of sea lice on salmon farms was most effective for controlling outbreaks in wild salmon, while uncoordinated treatments led to a resurgence of sea lice on salmon farms during the juvenile salmon migration. This study highlights the importance of incorporating spatiotemporal variability when considering infectious disease dynamics shared by farmed and wild hosts, particularly when migratory wildlife are involved.
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Vollset, Knut Wiik, Elina Halttunen, Bengt Finstad, Ørjan Karlsen, Pål Arne Bjørn y Ian Dohoo. "Salmon lice infestations on sea trout predicts infestations on migrating salmon post-smolts". ICES Journal of Marine Science 74, n.º 9 (1 de junio de 2017): 2354–63. http://dx.doi.org/10.1093/icesjms/fsx090.
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Abstract Impacts of sea lice (Lepeophtheirus salmonis or Caligus spp.) on wild salmonids is currently one of the most important issues facing management of fish farms in salmon producing countries in the northern hemisphere. Surveillance of sea lice on wild Atlantic salmon (Salmo salar) is often hampered by the ability to catch enough migrating post-smolts. Therefore, sea lice abundance on anadromous trout (Salmo trutta) is often used to infer sea lice abundance on migrating salmon post-smolt. However, the assumption that there is a relationship between the abundance of lice on salmon and trout has never been tested. Here we use a dataset of sea lice on salmon post-smolt and sea trout that have been caught simultaneously in trawl hauls, to evaluate the correlation in abundance of sea lice between the two species using various statistical models. We demonstrate that trout generally has higher abundances of sea lice than salmon. Average lice per gram fish on sea trout (log transformed) predicted the abundance of lice on salmon best. Negative binomial models of lice counts were preferable to using trout lice counts as direct estimates of salmon lice abundance, and they had better predictive ability than logit models of high (vs. low) lice counts. Including the size of the salmon increased the predictive ability of the model, but these data are not generally available. The effect of salmon weight may have been a direct effect of body size, or an indirect effect of time spent in marine waters. Finally, we predict lower salmon lice counts on migrating salmon with our selected binomial model than with the current method of using trout lice counts as a direct estimator on salmon lice counts, and demonstrate that management advice would change considerably depending on the chosen method.
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Price, M. H. H., A. Morton y J. D. Reynolds. "Evidence of farm-induced parasite infestations on wild juvenile salmon in multiple regions of coastal British Columbia, Canada". Canadian Journal of Fisheries and Aquatic Sciences 67, n.º 12 (diciembre de 2010): 1925–32. http://dx.doi.org/10.1139/f10-105.
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Salmon farms are spatially concentrated reservoirs of fish host populations that can disrupt natural salmonid host–parasite dynamics. Sea lice frequently infect farm salmon and parasitize sympatric wild juvenile salmonids, with negative impacts on survival in Europe and Pacific Canada. We examined louse parasitism of wild juvenile chum salmon ( Oncorhynchus keta ) and pink salmon ( Oncorhynchus gorbuscha ) from three salmon farming regions in British Columbia (Finlayson, Broughton Archipelago, and Georgia Strait). We compared sites of low and high exposure to farms and included an area without farms (Bella Bella) to assess baseline infection levels. Louse prevalence and abundance were lowest and most similar to natural baseline levels at low-exposure sites and highest at high-exposure sites in all farm regions. A significantly greater proportion of the lice were Lepeophtheirus salmonis at high-exposure sites. Exposure to salmon farms was the only consistently significant factor to explain the variation in prevalence data, with a secondary role played by salinity. Our results support the hypothesis that salmon farms are a major source of sea lice on juvenile wild salmon in salmon farming regions and underscore the importance of using management techniques that mitigate threats to wild stocks.
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Krkošek, Martin y Ray Hilborn. "Sea lice (Lepeophtheirus salmonis) infestations and the productivity of pink salmon (Oncorhynchus gorbuscha) in the Broughton Archipelago, British Columbia, Canada". Canadian Journal of Fisheries and Aquatic Sciences 68, n.º 1 (enero de 2011): 17–29. http://dx.doi.org/10.1139/f10-137.
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The spread of salmon lice ( Lepeophtheirus salmonis ) from salmon farms may threaten some wild salmon populations. Infestations of wild juvenile pink salmon ( Oncorhynchus gorbuscha ) have been associated with high mortality and population decline. Using stock–recruit data for pink salmon from the central coast of British Columbia, we analyzed how fishing mortality and spatial covariation combine with louse infestation to affect pink salmon population dynamics. The results indicate substantial coherence in survival at nested spatial scales — large-scale regional covariation and smaller scale covariation within management areas. Populations exposed to salmon farms (those from the Broughton Archipelago) show a sharp decline in productivity during sea lice infestations relative to pre-infestation years. Unexposed populations (comprising four management areas) did not experience a change in productivity during infestation years and had similar productivity to exposed populations before infestations. Our results suggest that sea lice infestations may result in declines of pink salmon populations and that management and policy of salmon farms should consider protecting wild juvenile salmon from exposure to sea lice.
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Riddell, Brian E., Richard J. Beamish, Laura J. Richards y John R. Candy. "Comment on "Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon"". Science 322, n.º 5909 (19 de diciembre de 2008): 1790.2–1790. http://dx.doi.org/10.1126/science.1156341.
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Krkošek et al. (Reports, 14 December 2007, p. 1772) claimed that sea lice spread from salmon farms placed wild pink salmon populations “on a trajectory toward rapid local extinction.” Their prediction is inconsistent with observed pink salmon returns and overstates the risks from sea lice and salmon farming.
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Shinn, A. P., B. A. Banks, N. Tange, J. E. Bron, C. Sommerville, T. Aoki y R. Wootten. "Utility of 18S rDNA and ITS sequences as population markers for Lepeophtheirus salmonis (Copepoda: Caligidae) parasitising Atlantic salmon (Salmo salar) in Scotland". Contributions to Zoology 69, n.º 1-2 (2000): 89–98. http://dx.doi.org/10.1163/18759866-0690102010.
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Genetic differentiation within the salmon louse Lepeophtheirus salmonis (Krøyer, 1837), was investigated by the sequencing of specific nucleotide regions. Partial sequences of the 18S ribosomal RNA gene and the ribosomal internal transcribed spacer (ITS-1) region from single sea lice were amplified by the polymerase chain reaction (PCR). Lice were collected from wild and farmed Atlantic salmon (Salmo salar L., 1758) from nine selected localities around the Scottish coastline. A 0.9kb fragment of the 18S ribosomal RNA gene was amplified and compared for several samples of lice which showed no observable differences between the lice from different collection sites confirming the absence of cryptic species. The 454 nucleotide ITS-1 sequence showed differences between derived sequences from 13 sea lice samples from 4 collection sites which included 2 farm sites and 2 sites where lice were taken from wild fish. Across all samples, there was a 92.14% similarity in the ITS-1 sequence. The percentage similarity in the ITS-1 sequence in samples office from two fish farms were 99.71% (site A) and 95.72% (site D) but only 86.90% (site B) and 86.03% (site C) similarity was shown in lice samples taken from sites where wild salmonids were caught. The greater similarity between the ITS-1 sequence within farm sites may be attributed to a restricted gene flow within lice populations in Atlantic salmon cage sites.
Tesis sobre el tema "Sea lice; Salmon farms"
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Banks, Bryony Alison. "Genetic characterisation of populations of the ectoparasitic copepod Lepeophtheirus salmonis (Kroyer, 1837) in Scotland". Thesis, University of Stirling, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391306.
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Penston, Michael. "Dynamics of planktonic larval sea louse distribution in relation to Atlantic salmon (Salmo salar L.) farms in a Scottish sea loch". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25799.
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Thesis (Ph.D.)--Aberdeen University, 2009.Title from web page (viewed on June 26, 2009). With: Spatial and temporal distribution of Lepeophtheirus salmonis (Krøyer) larvae in a sea loch containing Atlantic salmon, Salmo salra L., farms on the north-west coast of Scotland / M. J. Penston ... et al. Journal of fish diseases. 2008: 31, 361-371. With: Reduced Lepeophtheirus salmonis larval abundance in a sea loch on the west coast of Scotland between 2002 and 2006 / Michael J. Penston, Colin P. Millar, Ian Davies. Dis. Aquat. Org. 2008: 81, 109-117. Includes bibliographical references.
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Wadsworth, Simon Leigh. "The control of sea lice Lepeophtheirus salmonis (Kroyer, 1837) (Copepoda: Caligidae) on Atlantic salmon Salmon salar L., production sites". Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU532684.
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Sea lice Lepeophtheirus salmonis are the major pathogen affecting the salmon farming industry. Current methods of control, especially in the UK, are largely ineffective as they do not affect the chalimus stages of L. salmonis and are toxic to fish. Greater control of L. salmonis through improved management, more effective compounds, disease control and stock selection were examined. The epidemiology of L. salmonis on Atlantic salmon Salmo salar production sites was examined at a number of farms within Loch Sunart. Intensity of infection was found to be influenced by both management practices and seasonal variations. By instigating a series of co-ordinated, synchronous, strategic treatments throughout the loch system during the winter, initial chalimus levels during the spring were significantly reduced by 90% (p<0.001). Lice numbers for the rest of the production cycle were significantly lower (p<0.01). In addition there was a reduction in the number of treatments needed, an increase in the interval between treatments, reduced fish mortalities and improvements in fish harvest quality. There was no significant reduction in mean chalimus numbers observed at the control site where treatments were not co-ordinated. The strategic treatments were repeated in the Loch Linnhe system during 1997 resulting in an 87% (p<0.01) reduction in initial chalimus numbers. The efficacy of the synthetic pyrethroid, cypermethrin (Excis RTM) was assessed against L. salmonis chalimus. Exposure of the chalimus to 5mug I-1permethrin for 1 h resulted in a significant reduction (83%, p<0.001) in the mean number of chalimus 12 d post-treatment. The developmental stages observed in the untreated group were predominantly pre-adult II males. The majority of the remaining lice observed in the treated group were chalimus III indicating a profound effect of cypermethrin on the rate of development of L. salmonis. At 1 pg I-1permethrin for 1 h there was no significant reduction in the mean number of lice compared to controls (p=0.161) although there was a significant delay in the rate of development. A number of immunosuppressants were administered to Atlantic salmon and their effect examined upon the settlement and survival of Lepeophtheirus salmonis. Corticosteroid was found to increase the mean numbers of L. salmonis observed post-challenge by 59% (p<0.05) compared to controls. Administration of immunosuppressive factors isolated from Aeromonas salmonicida induced a 70% (p<0.01) increase in mean numbers of L. salmonis observed. There was no effect on the rate of development, nor tissue distribution of L. salmonis observed on the test fish compared to controls. The control of L. salmonis on production sites is examined in relation to disease status of the fish as well as the potential for effective immune modulation. Different stocks and families of Atlantic salmon Salmo salar were examined for variable susceptibility to settlement and survival of L. salmonis. Differences in susceptibility of up to 55% (p<0.01) in mean lice numbers were observed between stocks. Variability in susceptibility to settlement and survival, as well as damage caused by L. salmonis was also observed between families of Atlantic salmon.
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Micallef, Giulia. "Understanding the molecular basis of dietary protection against sea lice in Atlantic salmon : application of proteomics and transcriptomics". Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=204953.
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Yeast cell wall (YCW) extracts have long been regarded as beneficial supplements in aquaculture feeds, especially with respect to immunomodulation. Previous studies have shown that supplementing salmon diets with YCW extracts increases resistance to sea lice. During the series of three trials, different sea lice challenge models and YCW extracts were studied. In Trial 1, fish fed a diet containing 0.4% YCW #a exhibited a significant reduction in sea lice burden of 23% compared to the control diet. The skin and skin mucus samples from Trial 1 were hence used for high-throughput screening of altered transcripts and proteins, while searching for candidate biomarkers for YCW extracts. Samples from Trials 2 and 3 were used for testing the candidate transcripts in independent biological samples, hence confirming or otherwise their suitability as biomarkers. Due to the lack of skin-specific libraries in the salmonid EST database, Roche-454 sequencing was used to describe the skin transcriptome of Atlantic salmon and form the basis of successive experiments. The resulting transcriptome assembly included 4,108 transcripts that were previously unknown for salmon, which include both skin-specific and low-expression transcripts. Analysis of the mucus proteome by 2D gels of Trials 1 and 2 samples showed that 27 and 49 proteins, respectively, exhibited a change in expression due to dietary treatment (p<0.05). Of these, calreticulin-like protein showed greatest potential as a biomarker since its expression was changed in both Trials 1 and 2 at the proteomic level and Trials 2 and 3 at the transcriptomic level. RNAseq was carried out on Trial 1 skin samples and 375 transcripts were significantly altered in expression across dietary treatments (p<0.05). Validation of this data by qPCR was successful and yielded similar fold changes to the RNAseq output. However, when the expression of a selection of genes was studied in Trial 2 samples, no correlation was found and hence, no candidate biomarker molecules were discovered. While further work is required to deduce the underlying mechanisms of immunomodulation due to dietary YCW extracts, this project has yielded two skin-specific transcriptomic databases which may be used to enhance the genomic data for salmonids.
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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.
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Liu, Yajie. "An analysis of the management and economics of salmon aquaculture". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/323.
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Salmon aquaculture can be a potential solution to bridge the gap between declining capture fisheries and increasing seafood demand. However, the environmental impacts it creates have generated criticism. The overall objectives of this dissertation are to examine the economic consequences of environmental issues associated with salmon aquaculture, and to explore policy implications and recommendations for reducing environmental impacts. These objectives are addressed in five main analyses.
The growth of salmon aquaculture is analyzed based on farmed salmon production in the four leading producing countries and the sector as a whole. Analyses indicate that salmon aquaculture is unlikely to continue to grow at its current pace.
A joint production function approach is used to estimate pollution abatement costs for the salmon aquaculture industry. Results reveal that pollution abatement costs vary among observations and models. On average, pollution abatement cost is estimated at 3.5% in terms of total farmed salmon production, and 6.5% in terms of total revenue of farmed salmon.
The ecological and economic impacts of sea lice from salmon farms on wild salmon population and fisheries are also studied. Analyses suggest that these effects are minor when the sea lice induced mortality rate is below 20%, while they can be severe if the mortality is greater than 30%. Sea lice have greater ecological and economic impacts on pink salmon than on chum salmon. These effects are greater under a fixed exploitation rate than under a target escapement policy.
The economic performance of open netcage and sea-bag production systems for salmon aquaculture is compared. Netcage systems appear to be more economically profitable than sea-bag systems when environmental costs are either not or only partially included. Sea-bag systems can be financially profitable only when the salmon they produce can achieve a price premium.
Finally, policy implications are explored and recommendations are made for sustaining salmon aquaculture in a holistic manner based on the results from previous chapters. Technologies, economic-based instruments and more stringent environmental policies can be employed to reduce environmental impacts. However, there is no single solution to solve these environmental impacts, and a combination of policy options is needed.
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Tsai, Hsin Yuan. "Genomic basis of growth traits and host resistance against sea lice (L. Salmonis) in Atlantic salmon (S. Salar)". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28918.
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Background Atlantic salmon (Salmo Salar) is a key aquaculture species in several countries. Since its critical role in economic sector and scientific research, this species has been relatively extensively investigated, in comparison with other farmed and wild aquatic species. However, the genetic components associated with growth and fillet-related traits are lack consistency, and the issue of sea louse disease in both wild and famed salmon is still unsolved. Objectives Overall aim of this project was to understand the genetic basis of growth-related traits and host resistance to sea lice using three large commercial farmed salmon populations. Specifically, the method of quantitative trait loci (QTL) mapping, genome-wide association study (GWAS), and genomic prediction (GS) were utilized to dissect the genetic architectures associated with traits of interest in our experimental populations. Prior to this, linkage mapping was performed to construct a high-density linkage map for Atlantic salmon. Results Linkage map A linkage map was firstly constructed underlying a SNP array containing 132 K validated SNPs. 96,396 SNPs were successfully assigned to 29 chromosomes that correspond to the linkage group number of European Atlantic salmon. 6.5 % of unassigned contigs, which was equal to 1 % of recent whole genome reference assembly (GCA_000233375.4) anchored to exist chromosomes by referring to linkage mapping result. Genetic components associated with growth traits Heritabilities of growth-related traits were about 0.5 to 0.6 in adult and juvenile farmed salmon. The QTL mapping and GWAS suggested the growth-related traits are likely a polygenic genetic architecture with no major QTL segregating. The prediction accuracy estimated by genomic prediction showed that approximately 5,000 SNP markers could achieve the highest accuracy in body weight and length in juvenile salmon within population. Genetic components associated with lice resistance The heritability of lice resistance was 0.22 to 0.33 using pedigree and genetic relationship matrices respectively. GWAS indicated that the host resistance to sea lice was likely polygenic with no individual SNP surpassed the genome-wide significance threshold. Genomic prediction showed that about 5 to 10 K SNPs was able to achieve the asymptote of accuracy in closely related animals, while the greatest advantage of genomic prediction was observed in non-sibling test within population. Conclusions As the growth-related traits and lice resistance are both likely polygenic and population-specific, the genomic prediction is an efficient approach to capture the genetic variances of the traits in selection candidates in experimental population, especially for traits with low heritability such as flesh colour and lice resistance. Family-based selection method is the better choice than mass selection to accumulate the genetic effects in corresponding SNP platform. Given the high cost of genotyping and field data collection, the genotyping-by-sequencing and genotype imputation are likely the way to make significant improvements in relevant research.
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Sackville, Michael. "Of saline and sea lice : hydromineral challenges and osmoregulatory strategies associated with early ocean entry of juvenile pink salmon (Oncorhynchus gorbuscha)". Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27218.
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Pink salmon (Oncorynchus gorbuscha) enter seawater (SW) following gravel emergence at a body mass of 0.2 g. Two hydromineral challenges associated with this remarkable early ocean entry were investigated: (1) initial exposure to a hyper-osmotic environment and (2) sea louse (Lepeophtheirus salmonis) parasitism.
To survive SW, pink salmon were hypothesized to develop hypo-osmoregulatory abilities as larval alevins prior to natural SW entry as post-larval fry. To test this, alevins and fry were transferred from freshwater (FW) in darkness to SW under a simulated natural photoperiod (SNP). Ionoregulatory status was assessed at 0, 1 and 5 days post-transfer. Alevins showed no evidence of hypo-osmoregulation, marked by a loss of water balance, a 35% increase in body [Cl-], and no change in gill Na⁺/K⁺-ATPase (NKA) activity. Conversely, fry maintained water balance and increased gill NKA activity by 50%. Fry gill NKA activity also increased by 50% following exposure to SNP in FW, providing the first evidence of photoperiod-triggered smoltification for pink salmon. A 15% increase in fry body [Na⁺] was observed as well, perhaps representing a novel mechanism for maintaining water balance during ocean entry.
Physical damage to the host epidermis is a primary proximal effect of louse infection. Such damage may exacerbate existing hydromineral flux in SW. To test this, ionoregulatory status was measured in pink salmon of varying size with and without attached-stage lice. In laboratory-infected fish (~1 wk SW; 0.2-0.4 g), body [Na⁺] increased by 12% when infected with 1 chalimus IV louse, and by 23% with 2-3 chalimus III lice. Mortality was 6%. In wild-infected fish (~4-12 wks SW; 0.5-1.5 g), body [Na⁺] did not differ from controls. Combining data sets revealed a “no effect” fish size threshold of 0.5 g for 1 chalimus IV louse. This threshold is partly due to increasing hypo-osmoregulatory ability.
Pink salmon thus appear to possess a novel hypo-osmoregulatory strategy where ion balance is sacrificed to maintain water balance prior to maximum ion excretion capacity. Out-migrating fish are particularly vulnerable to sea louse parasitism at this time, and as such, BC fish farms have relocated to minimize interactions during this critical period.
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Nendick, Laura J. "The swimming performance and post-swim body ion concentrations of juvenile pink salmon, and the effect of parasitic sea lice on these parameters". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12630.
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Pink salmon (Oncorhynchus gorbuscha Walbaum) stocks in the Broughton Archipelago BC have seen a general decline in recent years. This is thought to be due to parasitism by sea lice, Lepeophtheirus salmonis (Krøyer, 1837), on pink salmon during early marine life stage. To investigate this, I measured swimming performance, an integrated measure of fish health, and post-swim body ion concentrations, a secondary stress response, of control and sea lice infected juvenile pink salmon (mass < 3.0 g).
Using five different protocols (ranging in duration from 8 – 112 min), four constant acceleration tests (rates between 0.005 - 0.053 cm s₋²) and a repeated critical swim speed test, it was found that the final swimming speed of juvenile pink salmon (mass <5.0 g) at baseline was independent of the swim protocol (P > 0.05). Given this finding, estimates of swim performance in juvenile pink salmon can be accurately measured with an acceleration test lasting < 10 minutes.
Using a repeated, constant acceleration (0.05 cm s₋²) protocol, the effects of sea lice on swimming performance and post-swim body ion concentrations were measured in artificially infected river-caught (RC-fish, mean body mass 0.3 + 0.05 g) and ocean-caught infected (OC-fish, mean body mass 1.1 + 0.1 g) juvenile pink salmon. Infection levels ranged in intensity (1 - 4 sea lice per fish) and development stage (chalimus 1 - adult). Swimming performance of RC-fish was not affected by lice intensity (P>0.05) but was affected by lice stage with swimming performance decreasing at chalimus 3 stage (-20.4%) and even further at more advanced sea lice stages (chalimus 4, -26.5%; motile, -37.9%). Sea lice parasitism had no significant effect on the swimming performance of larger OC-fish when compared to control. The absence of an additive effect on swimming performance of 1 to 3+ sea lice per fish suggests drag forces induced by the ectoparasite was not a major factor. In contrast, post-swim body Na⁺ and Cl- concentrations were typically elevated in infected compared to control RC-fish (P < 0.05), but not OC-fish (P > 0.05).
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Gravil, Helen Ruth. "Studies on the biology and ecology of the free swimming larval stages of Lepeophtheirus Salmonis (Kroyer, 1838) and Caligus Elongatus Nordmann, 1832 (Copepoda: Caligidae)". Thesis, University of Stirling, 1996. http://hdl.handle.net/1893/2380.
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The study investigated biological and ecological parameters controlling and influencing the production and distribution of the free-swimming larval stages of Lepeophtheirus salmonis (Kroyer, 1838), and to a lesser extent Caligus elongatus Nordmann 1832, in the natural environment The reproductive output of L. salmonis was influenced by seasonal effects. The number of eggs produced per brood showed an inverse relationship with increasing temperature. The number of eggs per brood was also influenced by adult female body size (cephalothorax length), which in itself exhibited an inverse relationship with increasing temperature. Photoperiod had no significant effect upon the number of eggs produced or on adult female size. Mean egg size of L. salmonis varied significantly over the year; larger eggs were produced during the summer months and smaller eggs over the winter. However, factors controlling the size of the eggs were not elucidated. The proportion of viable eggs per L. salmonis ovisac remained constant throughout the year. Large variations in egg number per egg string were found in both L. salmonis and C elongatus populations sampled at one point in time. These were attributed in part to phenotypic variation in adult female size and also the number of broods individual females had produced. Egg viability was not correlated with brood size, but mean egg size was related to the number of eggs per brood. Experimental studies indicated that hatching and development of L. salmonis was highly variable. The percentage of eggs hatched and the time period over which hatching occurred varied markedly, even when held under constant and optimal environmental conditions. Temperature did not affect hatching success or viability of the nauplius I stage, although at higher temperatures the period over which hatching occurred was reduced. Low and medium salinities caused a significant decrease in both hatching success and nauplius viability. Photoperiod had no effect on initiation of hatching. Hatching occurred in a manner similar to that observed in free-living copepods. The nauplii were enclosed by two egg membranes, the outer one bursting within the ovisac, the inner one after the ovisac membrane has split. Swelling of the egg and its subsequent hatching was attributed to osmotic effects, with water being taken up from the external environment. Development was also highly dependent upon both temperature and salinity. At 5'C, nauplius 11 stages failed to enter the moult to the copepodid stage. At 7.5'C, although moulting was initiated, in a large proportion of cases it was not successfully completed. At I O'C, development to the copepodid stage was successful. Nauplii only developed successfully to the copepodid stage at salinities of 25%o or greater. Copepodids raised under optimal conditions then exposed to a range of salinities had a greater salinity tolerance than nauplii. Biochemical analysis of the eggs of L. salmonis revealed that lipids constituted a large proportion of their dry weight. Naupliar stages contained a discrete area containing lipid which decreased in size over time, suggesting that the free-swimming larval stages utilised this as an energy reserve. Rate of depletion was faster in nauplii held at higher temperatures. Longevity, activity and infectivity of the infective stage decreased with age. However, both spontaneous and stimulus dependent activity ceased many hours before death and both activity and longevity were affected by temperature. Infectivity of I day old L. salmonis copepodids was higher than 7 day old larvae, and was considered to be related to the size of the energy reserves. The settlement and distribution pattern of copepodids did not change with age of copepodid, the majority being recorded from the fins. All three L. salmonis free-swimming larval stages demonstrated a "hop and sink" swimming pattern. The velocity and duration of both passive sinking and active swimming was recorded for both nauplii and copepodids. Although greater periods of time were spent passively sinking, the speeds obtained during both upward spontaneous and stimulated swimming meant that a net upward movement of larvae in the water column occurred. At higher temperatures spontaneous swimming activity increased, whilst low salinities caused a cessation of such ability. L. salmonis larvae were positively phototactic and negatively geotactic. As well as their positive responses to light intensity, the nauplius 11 and copepodid stages reacted positively to blue-green spectral wavelengths. Moulting times were relatively short, although the larvae were not able to swim during such periods. No relationship was found between the level of lipid reserves and the overall buoyancy of the larvae. Naupliar stages of both L. salmonis and C. elongalus were obtained from the water column as a result of a plankton sampling programme at a commercial Atlantic salmon farm. No copepodid stages of either species were found. There was no difference in the vertical distribution of the two L. salmonis naupliar stages. Live larvae tended to aggregate between 0 and 5m in depth, with no diurnal vertical migration. Dead nauplii, and those with low lipid reserves, were found deeper in the water column. Naupliar stages, and in particular the first larval stage, were concentrated in number within cages indicating that the cages have a retentive characteristic. A novel control method in the form of a commercially available light lure was tested. Though increasing the numbers of free-living copepods captured, it had no effect on the numbers of L. salmonis naupliar or copepodid stages obtained in plankton samples. The present study has therefore provided valuable data concerning the biology and ecology of the free-swimming larval stages of sea lice, in what was a comparatively poorly understood area.
Libros sobre el tema "Sea lice; Salmon farms"
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Semple, Walter G. Report on legal remedies in relation to sea trout protection and salmon farms in the west coast of Scotland. Glasgow: Bird Semple, 1996.
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Hogans, W. E. Infection dynamics of sea lice, Lepeophtheirus salmonis (Copepoda: Caligidae) parasitic on Atlantic Salmon (Salmo salar) cultured in marine waters of the Lower Bay of Fundy. St. Andrews, N.B: Biological Station, 1995.
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Whatcom County (Wash.). Division of Buildings and Code Administration., ed. Northwest Sea Farms salmon net-pens. [Bellingham, Wash.]: Department of Public Works, Division of Buildings and Code Administration, Whatcom County, Washington, 1989.
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Whatcom County (Wash.). Dept. of Public Works. Northwest Sea Farms Salmon net-pens Final EIS. 1989.
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Pauline, Mc Carney y Marine Institute, eds. National survey of sea-lice (lepeophtheirus salmonis Krøyer and caligus elongatus Nordmann) on fish farms in Ireland. Galway: Marine Institute, 2002.
Buscar texto completoCapítulos de libros sobre el tema "Sea lice; Salmon farms"
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Saksida, Sonja M., Diane Morrison, Mark Sheppard y Ian Keith. "Sea Lice Management on Salmon Farms in British Columbia, Canada". En Salmon Lice, 235–78. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9780470961568.ch8.
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Jackson, David. "Ireland: The Development of Sea Lice Management Methods". En Salmon Lice, 177–203. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9780470961568.ch6.
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Murray, Alexander G., Trish L. Amundrud, Michael J. Penston, Campbell C. Pert y Stuart J. Middlemas. "Abundance and Distribution of Larval Sea Lice in Scottish Coastal Waters". En Salmon Lice, 51–81. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9780470961568.ch2.
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Stucchi, Dario J., Ming Guo, Michael G. G. Foreman, Piotr Czajko, Moira Galbraith, David L. Mackas y Philip A. Gillibrand. "Modeling Sea Lice Production and Concentrations in the Broughton Archipelago, British Columbia". En Salmon Lice, 117–50. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9780470961568.ch4.
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Chang, Blythe D., Fred H. Page, Michael J. Beattie y Barry W. H. Hill. "Sea Louse Abundance on Farmed Salmon in the Southwestern New Brunswick Area of the Bay of Fundy". En Salmon Lice, 83–115. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9780470961568.ch3.
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Finstad, Bengt, Pål A. Bjørn, Christopher D. Todd, Fred Whoriskey, Patrick G. Gargan, Gregory Forde y Crawford W. Revie. "The Effect of Sea Lice on Atlantic Salmon and other Salmonid Species". En Atlantic Salmon Ecology, 253–76. Oxford, UK: Wiley-Blackwell, 2010. http://dx.doi.org/10.1002/9781444327755.ch10.
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Nowak, Barbara F., Melissa B. Martin y Sebastián Boltaña. "Parasitic Crustaceans". En Fisheries and Aquaculture, 401–34. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190865627.003.0016.
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This chapter provides a brief overview of crustacean parasites that infect commercially important fish and shellfish. Crustaceans are a diverse group of arthropods, with over 60,000 species that are significant to the aquaculture and fisheries sector, including parasitic species affecting other crustaceans, mollusks, and fishes. This chapter focuses on parasitic caligid copepods (sea lice), cymothoid isopods, and pea crabs of high economic impacts on commercially important aquatic species. The biology of the parasites, their effects on their hosts, the epidemiology of the infections, and economic impacts of these groups are described. Chemical treatments and husbandry modifications as management options for a range of crustacean parasites are presented, which includes the use of cleaner fish to remove parasites, specially designed cages to reduce infestation of parasites, or moving farms to deeper waters. The utilization of crustacean parasites as marine pest controls is further discussed, with emphasis on either its potential benefits or the negative effects on native crab populations. Despite the continuous adverse impacts parasitic crustaceans have on aquaculture, the progressive understanding of their biology and ecology may eventually lead to mitigation, if not complete eradication, of the parasites.
Actas de conferencias sobre el tema "Sea lice; Salmon farms"
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Frank, K., L. C. Gansel, A. M. Lien y J. Birkevold. "Effects of a Shielding Skirt for Prevention of Sea Lice on the Flow Past Stocked Salmon Fish Cages". En ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10882.
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The effect of a shielding skirt, a tarpaulin mounted from the surface down to 5 meter depth around a net cage, on the flow pattern at a commercially stocked salmon cage was investigated. Dye was used as a tracer for water movement and the dye spreading was monitored using aerial images. Current meters were employed to investigate the flow close to the net inside and outside the cage. Tests were conducted with and without the shielding skirt. The focus was on the effectiveness of the shielding skirt to deflect water around the cage. This study shows that a shielding skirt can reduce horizontal flow components significantly inside a cage, which is related to a reduction of water exchange. The flow towards a cage is divided by a shielding skirt, i.e. some of the water is transported around the cage, while some is passing underneath the shielding skirt. Some water entering the fish cage from underneath the tarpaulin is transported towards the surface inside the cage. The use of a shielding skirt might not prevent interaction of the upper water layers inside and outside of a fish cage completely, but it has the potential to reduce the inflow of surface water into the cage, if deployed properly.
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Turner, Adam A., Dean M. Steinke, Ryan S. Nicoll y Patrik Stenmark. "Comparison of Taut and Catenary Mooring Systems for Finfish Aquaculture". En ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78261.
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Finfish aquaculture has been expanding in areas like Norway and Canada over the last 20 years, and is projected to expand further in the next decades as the planet’s population and demand for seafood increases. Finding appropriate salmon farm sites is becoming increasingly difficult, as there are fewer protected nearshore locations available for development. As a result, there is interest in increased utilization of existing leases (i.e. permitted sites). These leases have a boundary in which the anchors and mooring lines must be contained. Reducing the footprint of the mooring arrangement will allow for an increased utilization of existing leases. A possible method to reduce the footprint of a spread moored salmon farm is to use a taut mooring rather than a chain catenary mooring. This requires the use of mooring materials and components that allows for handling of tidal elevation changes and wave action. This paper investigates the performance of a taut moored configuration with integrated Seaflex elastomeric mooring components in comparison with a conventional chain catenary configuration using dynamic analysis. The results show that a reduced footprint taut mooring configuration with integrated elastomeric mooring components can be substituted for a typical chain catenary mooring with no significant increase in peak mooring line loads at extreme sea states and significant reduction in peak loading at moderate and calm seastates.
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Kristiansen, David, Pål Lader, Per C. Endresen y Vegard Aksnes. "Numerical and Experimental Study on the Seakeeping Behavior of Floating Closed Rigid Fish Cages". En ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77254.
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The present paper addresses the seakeeping behavior of a rigid type of floating closed fish cages, with focus on effects of sloshing on the coupled motions and mooring loads. Closed cages have gained much attention recently as a strategy to avoid sea-lice infections in farming of Atlantic salmon. However, closed cages are novel structures and more knowledge is needed on the wave induced motions and coupling effects with sloshing for development of reliable closed cage structures to reduce risk for failure and possible escape of fish. In this paper, dedicated scaled model tests of closed cages in waves are presented and compared with numerical simulations using linear potential theory in frequency domain. The results shows that the influence of sloshing on the rigid body motion is significant. A nonlinear effect of sloshing was observed for a small region of excitation frequencies, where the surge amplitude increased with increasing wave steepness. Mean wave loads were also affected by sloshing. Hence, coupled motions with sloshing is important to consider in design of floating closed rigid fish cages and their mooring system.