| the population age structure and reproductive biology of gyrodactylus salaris malmberg (monogenea). | gyrodactylus salaris has recently become a major pathogen of atlantic salmon (salmo salar) in norway. the survivorship, population age structure and pattern of insemination of g. salaris were studied to determine the extent to which this species reproduces sexually. the age-specific mortality schedule of g. salaris could be described by an exponential model but day to day variations were large, with an increase in mortality after each birth. modelling population growth using the best fit mortali ... | 1994 | 8159462 |
| the effect of gyrodactylus salaris (monogenea) on the epidermis of atlantic salmon, salmo salar, parr in the river batnfjordselva, norway. | skin morphology of atlantic salmon, salmo salar, parr infected with gyrodactylus salaris was examined for 3 yr in the river batnfjordselva in norway and compared to that of uninfected salmon parr from a neighboring river. the epidermis of the infected population had more cell layers and was thicker than the epidermis of parr from the uninfected population. the number of mucous cells did not differ, and no seasonal changes in morphology of the epidermis were detected in either rivers. intensity o ... | 1997 | 9406797 |
| platyspondyly and shortness of vertebral column in farmed atlantic salmon salmo salar in norway--description and interpretation of pathologic changes. | body malformation due to shortness of the vertebral column, in most cases of unknown cause, has been observed in fish for more than 100 yr. it periodically occurs with high prevalence in farmed atlantic salmon salmo salar in norway, and this paper describes the results of macroscopic, radiographic and histologic examination of parr and seawater-transferred fish. the vertebral bodies in both age groups did not acquire the length that they normally should due to a growth disturbance leading to the ... | 2000 | 10715815 |
| nucleotide sequence variation in isolates of infectious salmon anaemia virus (isav) from atlantic salmon salmo salar in scotland and norway. | the nucleotide sequences of segments 2 and 8 of infectious salmon anaemia virus (isav) isolates from scotland and norway were determined and compared. sequence variations were found in both segments, with segment 2 being more variable. these variations were of the same degree as those found in previous comparisons of the first recorded strain of isav in scotland and norwegian strains for which sequence information was available. the sequences again demonstrate the separation of european and cana ... | 2000 | 11129383 |
| population growth of gyrodactylus salaris (monogenea) on norwegian and baltic atlantic salmon (salmo salar) stocks. | reproductive success of gvrodactylus salaris from river lierelva was compared experimentally on 3 stocks of salmon (12.5 degrees c +/- 0.2). isolated fish from 2 susceptible norwegian stocks (rivers lier and alta) and 1 resistant baltic stock of salmon (river neva) were infected with a single gravid worm in order to record the temporal sequence of births and age at death of individual parasites. establishment success (proportion of worms surviving to give birth) was generally low and mortality h ... | 2000 | 11155933 |
| epidemiology of bacterial diseases in norwegian aquaculture--a description based on antibiotic prescription data for the ten-year period 1991 to 2000. | in norway, antibacterial drugs for use in farmed fishes have to be prescribed by a veterinarian. moreover, a national surveillance programme requires that copies of all prescriptions be sent to the directorate of fisheries. the prescriptions give information regarding fish farm and locality, weight and species of fish to be medicated, diagnosis, type and amount of drug prescribed, and date. these prescription data for the 10 yr period 1991 to 2000 have been recorded and systematised. a total of ... | 2003 | 12650244 |
| mitochondrial dna variation of gyrodactylus spp (monogenea, gyrodactylidae) populations infecting atlantic salmon, grayling, and rainbow trout in norway and sweden. | approximately 800 bp of the mitochondrial cytochrome oxidase i (coi) gene were sequenced from 76 gyrodactylus specimens of 32 salmonid host populations, i.e. from salmo salar, thymallus thymallus, and oncorhynchus mykiss in norway, sweden and latvia. the coi sequences indicated a substantial intraspecific differentiation of gyrodactylus salaris and gyrodactylus thymalli. in total, 12 haplotypes were identified which group into five well supported clades, three clades with parasites from atlantic ... | 2003 | 14572510 |
| a comparison of epidemiological patterns of salmon lice, lepeophtheirus salmonis, infections on farmed atlantic salmon, salmo salar l., in norway and scotland. | this paper examines two large national data sets collected over several years and contrasts the patterns of sea lice, lepeophtheirus salmonis (krøyer, 1837), infections, the use of treatments and the occurrence of chalimus peaks between norwegian and scottish farms. infection levels in scotland were significantly higher in general over the period under study. for the chalimus stage group in the first quarter of the year, norwegian mean abundance stayed below 10 lice per m2 while scottish means r ... | 2003 | 14575372 |
| cardiomyopathy syndrome in farmed atlantic salmon salmo salar: occurrence and direct financial losses for norwegian aquaculture. | cardiomyopathy syndrome (cms) was first diagnosed in the mid-1980s in farmed atlantic salmon in norway, and later also in scotland and the faeroe islands. in norway the number of diagnosed cases increased from 25 to 103 in the period from 1998 to 2001 according to the national veterinary institute (nvi) records. very little is known about the causes of the disease and there is no documentation of its impact on the farmed salmon industry. this field survey was performed to collect information on ... | 2003 | 14667036 |
| pathology of heart and skeletal muscle inflammation (hsmi) in farmed atlantic salmon salmo salar. | this is the first description of heart and skeletal muscle inflammation (hsmi), a novel disease affecting farmed atlantic salmon salmo salar in norway. hsmi was first diagnosed in 1999, and there has since been a yearly increase in the number of recorded outbreaks. atlantic salmon are commonly affected 5 to 9 mo after transfer to sea, but outbreaks have been recorded as early as 14 d following seawater transfer. affected fish are anorexic and display abnormal swimming behaviour. autopsy findings ... | 2004 | 15264718 |
| local-scale density-dependent survival of mobile organisms in continuous habitats: an experimental test using atlantic salmon. | for organisms with restricted mobility, density dependence may occur on spatial scales much smaller than that of the whole population. averaging densities over whole populations in such organisms gives a more or less inaccurate description of the real variation in competitive intensity over time and space. the potential for local density dependence in more mobile organisms is less well understood, particularly for organisms living in continuous habitats. to test for local density-dependent proce ... | 2005 | 15654640 |
| transmission of infectious salmon anaemia virus (isav) in farmed populations of atlantic salmon (salmo salar). | in the present study, 24 smolt production sites were screened for the presence of infectious salmon anaemia virus (isav) with the help of a specific real-time rt pcr assay, and 22 of these sites had smolts that were positive. if these smolt production sites are representative for the prevalence of isav in norwegian smolts, then most marine production sites must be considered to be positive for isav. in addition, 92 european isav isolates have been genotyped based on the hemagglutinin-esterase ge ... | 2007 | 16941061 |
| caligus elongatus nordmann genotypes on wild and farmed fish. | two mitochondrial genotypes have been described for caligus elongatus nordmann in norway. this article reports on the distribution of c. elongatus mitochondrial cytochrome c oxidase 1 genotypes from wild fish hosts from the se norwegian coast. for comparison, lice from areas with fish farming were included in the study. the genotype distribution of 841 lice from wild coastal (n = 535), wild north sea pelagic (n = 26), farmed (n = 160) and wild hosts in areas of fish farming (n = 89) is presented ... | 2007 | 17298563 |
| the biology of gyrodactylid monogeneans: the "russian-doll killers". | this article reviews the history of gyrodactylid research focussing on the unique anatomy, behaviour, ecology and evolution of the viviparous forms while identifying gaps in our knowledge and directions for future research. we provide the first summary of research on the oviparous gyrodactylids from south american catfish, and highlight the plesiomorphic characters shared by gyrodactylids and other primitive monogeneans. of these, the most important are the crawling, unciliated larva and the spi ... | 2007 | 17499102 |
| accumulation and depuration of the synthetic antioxidant ethoxyquin in the muscle of atlantic salmon (salmo salar l.). | the biological fate of the fish feed additive, ethoxyquin (eq) was examined in the muscle of atlantic salmon during 12 weeks of feeding followed by a 2 weeks depuration period. parent eq (1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline), quinone imine (2,6-dihydro-2,2,4-trimethyl-6-quinolone), de-ethylated eq (6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline) and eqdm (eq dimer or 1,8'-di(1,2-dihydro-6-ethoxy-2,2,4-trimethyl-quinoline) were found to be the ubiquitous metabolites of dietary eq, with ... | 2008 | 18329775 |
| morphogenesis of salmonid gill poxvirus associated with proliferative gill disease in farmed atlantic salmon (salmo salar) in norway. | proliferative gill disease (pgd) is an emerging problem in norwegian culture of atlantic salmon (salmo salar). parasites (ichthyobodo spp.) and bacteria (flexibacter/flavobacterium) may cause pgd, but for most cases of pgd in farmed salmon in norway, no specific pathogen has been identified as the causative agent. however, neoparamoeba sp. and several bacteria and viruses have been associated with this disease. in the spring of 2006, a new poxvirus, salmon gill poxvirus (sgpv), was discovered on ... | 2008 | 18521535 |
| divergent trends in anadromous salmonid populations in norwegian and scottish rivers. | the atlantic salmon (salmo salar) is a charismatic anadromous fish of high conservation and economic value. concerns have been expressed regarding the long-term viability of fisheries throughout the species's distributional range because of abundance variations that cannot currently be explained or predicted. here, we analyse long-term catch data obtained over a wide geographical range and across a range of spatial subscales to understand more fully the factors that drive population abundance. w ... | 2009 | 19129101 |
| (13)c nmr pattern recognition techniques for the classification of atlantic salmon (salmo salar l.) according to their wild, farmed, and geographical origin. | (13)c nuclear magnetic resonance (nmr) in combination with multivariate data analysis was used to (1) discriminate between farmed and wild atlantic salmon ( salmo salar l.), (2) discriminate between different geographical origins, and (3) verify the origin of market samples. muscle lipids from 195 atlantic salmon of known origin (wild and farmed salmon from norway, scotland, canada, iceland, ireland, the faroes, and tasmania) in addition to market samples were analyzed by (13)c nmr spectroscopy ... | 2009 | 19348423 |
| pancreas disease (pd) in sea-reared atlantic salmon, salmo salar l., in norway; a prospective, longitudinal study of disease development and agreement between diagnostic test results. | a prospective longitudinal study was performed on three cages at each of three norwegian atlantic salmon seawater sites that experienced outbreaks of pancreas disease (pd). once salmonid alphavirus (sav) ribonucleic acid (rna) was detected by real-time rt-pcr (rt rt-pcr) at a site, it became detected in all studied cages and was persistently found until the end of the study period up to 19 months after first detection. sav-specific antibodies were detected at all sites until the end of the study ... | 2010 | 20609035 |
| infectious salmon anemia virus--genetics and pathogenesis. | the infectious salmon anemia virus (isav) is the causative agent of the isa syndrome that affects mainly atlantic salmon (salmo salar) and has caused high mortality epidemics in norway, scotland, canada, the united states and chile. it is classified as an orthomyxoviridae, its genome is composed of 8 single-strand rna segments with negative polarity that code for 11 polypeptides. through functional studies of the coded proteins it has been established that rna segments 5 and 6 code for a fusion ... | 2010 | 20979983 |
| modelling the spread of infectious salmon anaemia among salmon farms based on seaway distances between farms and genetic relationships between infectious salmon anaemia virus isolates. | infectious salmon anaemia (isa) is an important infectious disease in atlantic salmon farming causing recurrent epidemic outbreaks worldwide. the focus of this paper is on tracing the spread of isa among norwegian salmon farms. to trace transmission pathways for the isa virus (isav), we use phylogenetic relationships between virus isolates in combination with space-time data on disease occurrences. the rate of isa infection of salmon farms is modelled stochastically, where seaway distances betwe ... | 2011 | 21325314 |
| original observations of desmozoon lepeophtherii, a microsporidian hyperparasite infecting the salmon louse lepeophtheirus salmonis, and its subsequent detection by other researchers. | abstract: a microsporidian hyperparasite, desmozoon lepeophtherii, of the parasitic copepod lepeophtheirus salmonis (salmon louse), infecting farmed atlantic salmon (salmo salar), was first discovered in the west of scotland in 2000. heavily infected salmon lice are easily recognised as they have large opaque inclusions distributed throughout the body. the prevalence of salmon lice with visible signs of microsporidiosis can be up to 10% of the population from certain farm sites. the microsporidi ... | 2011 | 22166354 |
| seawater tolerance and post-smolt migration of wild atlantic salmon salmo salar × brown trout s. trutta hybrid smolts. | high levels of hybridization between atlantic salmon salmo salar and brown trout salmo trutta have been reported in the river driva. this study presents the underlying mechanisms of development of seawater (sw) tolerance and marine migration pattern for s. salar×s. trutta hybrids. migrating s. salar×s. trutta hybrid smolts caught in the river driva, norway (a river containing gyrodactylus salaris), displayed freshwater (fw) gill na(+), k(+) -atpase (nka) activity levels of 11·8 µmol adp mg prote ... | 2012 | 23331146 |
| immune parameters correlating with reduced susceptibility to pancreas disease in experimentally challenged atlantic salmon (salmo salar). | two strains of atlantic salmon (salmon salar) with different susceptibility to infectious salmon anaemia (isa) were challenged with salmon pancreas disease virus (spdv), the etiological agent of salmon pancreas disease (pd), by cohabitation. serum and tissues were sampled at 0, 1, 3, 6 and 8 weeks post-challenge. experimental challenge with sav did not cause mortality, but virus loads and assessment of histopathology indicated that the fish more resistant to isav (isahi) also was more resistant ... | 2013 | 23306092 |
| piscine orthoreovirus (prv) infects atlantic salmon erythrocytes. | piscine orthoreovirus (prv) belongs to the reoviridae family and is the only known fish virus related to the orthoreovirus genus. the virus is the causative agent of heart and skeletal muscle inflammation (hsmi), an emerging disease in farmed atlantic salmon (salmo salar l.). prv is ubiquitous in farmed atlantic salmon and high loads of prv in the heart are consistent findings in hsmi. the mechanism by which prv infection causes disease remains largely unknown. in this study we investigated the ... | 2014 | 24694042 |
| first detection of piscine reovirus (prv) in marine fish species. | heart and skeletal muscle inflammation (hsmi) is a disease that affects farmed atlantic salmon salmo salar l. several months after the fish have been transferred to seawater. recently, a new virus called piscine reovirus (prv) was identified in atlantic salmon from an outbreak of hsmi and in experimentally challenged fish. prv is associated with the development of hsmi, and has until now only been detected in atlantic salmon. this study investigates whether the virus is also present in wild fish ... | 2012 | 22422096 |
| salmonid alphavirus infection causes skin dysbiosis in atlantic salmon (salmo salar l.) post-smolts. | interactions among host, microbiota and viral pathogens are complex and poorly understood. the goal of the present study is to assess the changes in the skin microbial community of atlantic salmon (salmo salar l.) in response to experimental infection with salmonid alphavirus (sav). the salmon skin microbial community was determined using 16s rdna pyrosequencing in five different experimental groups: control, 7 days after infection with low-dose sav, 14 days after infection with low-dose sav, 7 ... | 2017 | 28264056 |
| genetic characterization of salmonid alphavirus in norway. | pancreas disease (pd), caused by salmonid alphavirus subtype 3 (sav3), emerged in norwegian aquaculture in the 1980s and is now endemic along the south-western coast. in 2011, the first cases of pd caused by marine salmonid alphavirus subtype 2 (sav2) were reported. this subtype has spread rapidly among the fish farms outside the pd-endemic zone and is responsible for disease outbreaks at an increasing numbers of sites. to describe the geographical distribution of salmonid alphavirus (sav), and ... | 2016 | 25683753 |
| associations between piscine reovirus infection and life history traits in wild-caught atlantic salmon salmo salar l. in norway. | piscine reovirus (prv), the putative causative agent of heart and skeletal muscle inflammation (hsmi), is widely distributed in both farmed and wild atlantic salmon (salmo salar l.) in norway. while hsmi is a common and commercially important disease in farmed atlantic salmon, the presence of prv has so far not been associated with hsmi related lesions in wild salmon. factors associated with prv-infection were investigated in returning atlantic salmon captured in norwegian rivers. a multilevel m ... | 2013 | 23906390 |
| a survey of the distribution of the pkd-parasite tetracapsuloides bryosalmonae (cnidaria: myxozoa: malacosporea) in salmonids in norwegian rivers - additional information gleaned from formerly collected fish. | the malacosporean tetracapsuloides bryosalmonae was detected in kidneys from atlantic salmon parr in 64 of 91 sampled norwegian rivers. using real-time pcr, this parasite was found to be present in atlantic salmon parr in rivers along the whole coast, from the northernmost and southernmost areas of the country. in addition, t. bryosalmonae was found in kidneys from brown trout parr in 17 of 19 sampled rivers in south-east norway, and in arctic charr sampled in the river risfjordelva, located at ... | 2017 | 27523592 |
| infection experiments with novel piscine orthoreovirus from rainbow trout (oncorhynchus mykiss) in salmonids. | a new disease in farmed rainbow trout (onchorhyncus mykiss) was described in norway in 2013. the disease mainly affected the heart and resembled heart and skeletal muscle inflammation (hsmi) in atlantic salmon (salmo salar l.). hsmi is associated with piscine orthoreovirus (prv), and a search for a similar virus in the diseased rainbow trout led to detection of a sequence with 85% similarity to prv. this finding called for a targeted effort to assess the risk the new prv-variant pose on farmed r ... | 2017 | 28678799 |
| the economic benefits of disease triggered early harvest: a case study of pancreas disease in farmed atlantic salmon from norway. | pancreas disease (pd) is an important viral disease in norwegian, scottish and irish aquaculture causing biological losses in terms of reduced growth, mortality, increased feed conversion ratio, and carcass downgrading. we developed a bio-economic model to investigate the economic benefits of a disease triggered early harvesting strategy to control pd losses. in this strategy, the salmon farm adopts a pcr (polymerase chain reaction) diagnostic screening program to monitor the virus levels in sto ... | 2015 | 26297077 |
| mortality related to pancreas disease in norwegian farmed salmonid fish, salmo salar l. and oncorhynchus mykiss (walbaum). | high mortality during the salmonid seawater phase is a continuous problem for the salmonid aquaculture industry, although the mortality levels show a large variation both in farms with a disease history and those without. we wanted to examine the mortality patterns in farms with pancreas disease (pd) and compare it to farms without this diagnosis. further, we wished to investigate the factors influencing the maximum mortality in both groups. we examined data from all salmonid farms in norway sto ... | 2013 | 23311767 |