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Morhua L. (morhua + l)
Kinds of Morhua L. Selected AbstractsIMPACT OF FREEZING TEMPERATURE ON QUALITY OF FARMED ATLANTIC COD (GADUS MORHUA L.)JOURNAL OF TEXTURE STUDIES, Issue 4 2007TURID MØRKØRE ABSTRACT This study evaluates the impact of freezing temperature (,10,,25,,40,,55 or,70C) on thaw exudates, liquid leakage during freeze-chilling, appearance, gaping and mechanical properties of farmed Atlantic cod fillets. Freezing temperature significantly influenced each of the characteristics studied. High temperatures (,10 and,25C) gave increased thaw exudates, and freezing at,10C gave the highest liquid leakage during freeze-chilling. Fillets frozen at,10C had the lowest gaping and the whitest appearance. The results indicated the highest degree of toughening upon freezing at,10 or,55C, whereas the degree of toughening appeared to be similar and lower for fillets frozen at,25,,40 or,70C. The impact of freezing temperatures on the quality of farmed cod therefore appeared to be complex, but no overall beneficial effects were found by decreasing the freezing temperature below,40C. PRACTICAL APPLICATIONS For the fish processing industry, it is important to define optimal freezing and frozen storage regimes that are cost efficient and at the same time preserve the fresh fillet quality. Farmed cod differ from their wild counterparts by having lower water content, lower muscle pH and thicker fillets. Hence, industrial guidelines for wild cod may not be transferable to farmed cod. This study showed no beneficial effects by decreasing the freezing temperature below ,40C. Freezing and frozen storage are usually separated commercially. Results from the present study give valuable contribution to future studies aiming at defining optimal combination of freezing and frozen storage temperatures for farmed Atlantic cod. [source] The influence of oxygen saturation on the distributional overlap of predator (cod, Gadus morhua) and prey (herring, Clupea harengus) in the Bornholm Basin of the Baltic SeaFISHERIES OCEANOGRAPHY, Issue 1 2002Stefan Neuenfeldt Environmental heterogeneity can create boundary conditions for the co-occurrence of marine predators and their prey. If one or both are spatially constrained by their tolerance to environmental variables, then spatial differences in the availability of possible habitats define the volume of distributional overlap. Cod (Gadus morhua L.) and its prey, herring (Clupea harengus L.), in the vertically stratified Bornholm Basin of the Baltic Sea are presented as an example. A non-linear model was used to estimate oxygen avoidance thresholds for both species. Herring avoided oxygen saturation levels below 50%, while cod tolerated oxygen saturation down to 16%. The threshold of 50% oxygen saturation, below which cod could not encounter its prey, herring, was applied to a time series of vertical oxygen profiles from the centre of the Bornholm Basin to estimate the size of the overlap volume during the winter period from 1958 to 1999. Dependent on the oxygenation of the deep-water, the overlap volume varied between 57 km3 and 250 km3. [source] Patterns in the spawning of cod (Gadus morhua L.), sole (Solea solea L.) and plaice (Pleuronectes platessa L.) in the Irish Sea as determined by generalized additive modellingFISHERIES OCEANOGRAPHY, Issue 1 2000Eleven ichthyoplankton cruises were undertaken covering most of the Irish Sea during the period February to June, 1995. To identify spawning localities and investigate temporal trends in egg production, the data on stage 1 A egg distributions of cod (Gadus morhua), plaice (Pleuronectes platessa) and sole (Solea solea) have been modelled using generalized additive models (GAMs). A two-stage approach was adopted where presence/absence was firstly modelled as a binary process and a GAM surface subsequently fitted to egg production (conditional on presence). We demonstrate that this approach can be used to model egg production both in space and in time. The spawning sites for cod, plaice and sole in the Irish Sea were defined in terms of the probability of egg occurrence. For cod, we demonstrate that by integrating under predicted egg production surfaces, a cumulative production curve can be generated and used to define percentiles of production and thus delimit the extent of the spawning season. However, for plaice and sole, the surveys did not fully cover the spawning season and the limitations that this imposes on GAM modelling of these data are discussed. Comparison of the spawning sites in 1995 with historical data suggests that the locations of cod, plaice and sole egg production in the Irish Sea have probably remained relatively constant over the last 30 years. [source] Tissue tropism of nervous necrosis virus (NNV) in Atlantic cod, Gadus morhua L., after intraperitoneal challenge with a virus isolate from diseased Atlantic halibut, Hippoglossus hippoglossus (L.)JOURNAL OF FISH DISEASES, Issue 8 2009K Korsnes Abstract Atlantic cod, Gadus morhua, averaging 100 g, were experimentally challenged by intraperitoneal injection of nervous necrosis virus (NNV) originating from Atlantic halibut. Cod tissues, including blood, gill, pectoral fin, barbel, ventricle, atrium, spleen, liver, lateral line (including muscle tissue), eye (retina) and brain, were sampled at day 25 and 130 and investigated by real-time RT-PCR for the presence of NNV. Relative quantifications at day 130 were calculated using the 2,,,Ct method. Immunosuppression by injection of prednisolone-acetate was introduced for a 30-day period, and tissue sampled at day 180 and relative quantification estimated. No mortality or clinical signs of disease were observed in the challenged group. The challenge resulted in detection of NNV in blood, spleen, kidney, liver, heart atrium and heart ventricle at day 25, and by the end of the experiment NNV showed a clear increase in brain and retina, suggesting these to be the primary tissues for viral replication. There was no increase in the relative amount of NNV in blood, atrium, ventricle, spleen, liver and kidney. Corticosteroid implants resulted in a weak increase in virus RNA in spleen, kidney, liver and brain. These findings suggest that Atlantic cod is susceptible to infection with NNV from halibut. The observed tissue tropism patterns suggest an initial viraemic phase, followed by neurotrophy. Head-kidney is the best tissue identified for possible NNV detection by non-lethal biopsy, but detection was not possible in all injected fish. [source] Phenotypic, serological and genetic characterization of Pseudomonas anguilliseptica strains isolated from cod, Gadus morhua L., in northern EuropeJOURNAL OF FISH DISEASES, Issue 11 2007S Balboa Abstract The biochemical, serological and genetic characteristics of six strains of Pseudomonas anguilliseptica isolated from cod, Gadus morhua, in Scotland were compared to well characterized isolates of this same bacterial species but of different origin. Biochemical and physiological analyses showed that this group of isolates was highly homogeneous, their characteristics matching previous descriptions of the pathogen. Similar results were obtained for the six cod isolates in the serological assays, all of them belonging to the serotype O1. Marked homogeneity was observed also in the genetic study, analysed by means of RAPD, ERIC-PCR and REP-PCR procedures, showing that they were similar to isolates from gilthead seabream, Sparus aurata, black spot seabream, Pagellus bogaraveo, and turbot, Psetta maxima. Virulence assays demonstrated that the cod isolates were highly pathogenic for turbot and sole, Solea senegalensis, with LD50 between 7.6 × 104 and 5 × 107 bacterial cells per fish. [source] Atypical Aeromonas salmonicida infection in naturally and experimentally infected cod, Gadus morhua L.JOURNAL OF FISH DISEASES, Issue 10 2002B Magnadóttir Abstract Cod, Gadus morhua L., of wild origin, were reared at different temperatures for 12 months. During this period, moribund and newly dead fish were examined and samples collected for bacteriology and histopathology. Atypical Aeromonas salmonicida was isolated from 10 individuals reared at or above 7 °C. The isolates were homogeneous with respect to biochemical and antibiogram characters and similar to the ssp. achromogenes National Collection of Industrial and Marine Bacteria, UK, type strain 1110 and reference strains that have been isolated from salmonids and haddock in Iceland. Histopathological analysis of the naturally infected cod showed typical ulceration associated with atypical A. salmonicida infection and also widespread granulomatous formations. One-year-old cod of farmed origin, kept at 9 °C, received intraperitoneal or intramuscular injection with different doses of atypical A. salmonicida, isolated from the above wild cod. Mortalities were monitored for 28 days and the LD50 calculated. The route of bacterial injection influenced the mortality rate and LD50 value and affected, to some extent, the pathological changes observed and humoral immune parameters. Pathological changes, including haemorrhage, early stages of granuloma formation and necrotic changes, were seen in several organs. Infection appeared to induce non-specific antibody activity against trinitrophenyl (TNP)-haptenated protein and may have activated the complement system. Specific antibody response against atypical A. salmonicida was not detected. [source] Characterization of 18 new microsatellite loci in Atlantic cod (Gadus morhua L.)MOLECULAR ECOLOGY RESOURCES, Issue 6 2008SIGURLAUG SKIRNISDOTTIR Abstract Eighteen new microsatellite loci consisting of 10 di-, 5 tri-, 2 tetra- and 1 heptanucleotide repeats are introduced for the Atlantic cod (Gadus morhua L.). All loci were co-amplified in two polymerase chain reactions (plus two previously published microsatellites) and all products were typed clearly. The number of alleles per locus ranged from six (PGmo130) to 45 (PGmo76) and the observed heterozygosity ranged from 0.356 (PGmo130) to 0.957 (PGmo95). All loci except one followed Hardy,Weinberg expectations. Genetic linkage disequilibrium analysis between all pairs of loci did not yield any significant values. [source] Development of 25 gene-associated microsatellite markers of Atlantic cod (Gadus morhua L.)MOLECULAR ECOLOGY RESOURCES, Issue 4 2006JØRGEN STENVIK Abstract Microsatellites were identified by screening 2294 GenBank entries available for Atlantic cod (Gadus morhua L.), mainly representing expressed sequence tags and cDNA sequences. Ninety-two novel microsatellite loci (tetra-, tri- and dinucleotides) were characterized on 96 individuals. This strategy yielded 25 gene-associated polymorphic microsatellite markers (11 tri- and 14 dinucleotides) with two to 20 alleles and an average heterozygosity of 0.48 in the population studied (range 0.02,0.89). One marker exhibited significant homozygote excess, and one of the primer pairs amplified two linked markers. The gene identity was determined at nine of the loci, confirming the associated microsatellites as type I markers. [source] Nine new polymorphic microsatellite loci for the amplification of archived otolith DNA of Atlantic cod, Gadus morhua L.MOLECULAR ECOLOGY RESOURCES, Issue 2 2006KLARA BJÖRG JAKOBSDÓTTIR Abstract Nine out of 22 microsatellite primers tested were successfully amplified on three samples of cod Gadus morhua L. (two contemporary and one archived otolith samples). All loci were polymorphic (5,23 alleles/locus). The average observed heterozygosity across loci and samples was 0.625, ranging from 0.294 to 0.895 at each locus. All loci were under Hardy,Weinberg equilibrium, except PGmo56 that showed significant excess of heterozygotes in all studied samples. The isolated loci were suitable for degraded DNA and therefore useful for conducting a long-term temporal study with DNA obtained from archived otoliths of cod. [source] Genotyping of pantophysin I (Pan I) of Atlantic cod (Gadus morhua L.) by allele-specific PCRMOLECULAR ECOLOGY RESOURCES, Issue 1 2006JØRGEN STENVIK Abstract The two main allelic variants of the Atlantic cod (Gadus morhua L.) pantophysin I (Pan I) locus have different frequencies within different cod stocks. The Dra I polymorphism which distinguishes the two alleles can thus be used for discrimination of coastal and offshore cod populations. We present a new method for Pan I genotyping using fluorescent allele-specific duplex polymerase chain reaction (PCR). This method is more rapid, reliable and cost-effective than the previously published method and it is not affected by DNA source and quality. This improvement is important for studies demanding high throughput and accuracy of Pan I genotyping [source] A method to determine protein digestibility of microdiets for larval and early juvenile fishAQUACULTURE NUTRITION, Issue 6 2009J.M. HANSEN Abstract A method to evaluate protein quality using in vivo methods was developed for larval fish. FluoSpheres® fluorescent microspheres (10 ,m) were incorporated into two test diets, our standard zein microdiet (ZMD) and a microdiet with identical ingredients except for the replacement of high quality fish meal with the same product cooked for 24 h at 80 °C (ZMD-CF). Several trials were performed to design a reliable method to test digestibility using FluoSpheres® as a marker. The developed in vivo technique was tested on 35 days posthatch (dph) larval Atlantic cod (Gadus morhua L.) and two tropical fish species in the early juvenile stage. The method took into account loss of total protein to the faecal pellet and water column. Apparent digestibility of protein in larval cod fed ZMD was significantly higher than that of larvae fed ZMD-CF (P < 0.05). A growth study to validate differences between the two diets showed significant differences in growth and survival of larvae fed ZMD versus ZMD-CF (P < 0.05). Further validation of our results was indicated through the use of a pH-stat method using enzymes extracted from 35 dph larval cod guts. This novel technique will be advantageous for researchers to evaluate feed ingredients for larval marine fish and is adaptable to many different areas of larval fish nutrition. [source] Effects of protein hydrolysate in weaning diets for Atlantic cod (Gadus morhua L.) and Atlantic halibut (Hippoglossus hippoglossus L.)AQUACULTURE NUTRITION, Issue 2 2009A. KVÅLE Abstract The study aims to test whether predigested dietary protein enhances the utilization of formulated diets at weaning, and also whether it stimulates intestinal maturation. In this study, Atlantic cod [Gadus morhua L.; 41 days posthatch (dph)] and Atlantic halibut [Hippoglossus hippoglossus L.; 63 days postfirst feeding (dpff)] were weaned onto diets with graded levels of protein hydrolysate. By increasing the inclusion of dietary protein as hydrolysate from 0 to 400 g kg,1, cod increased the rate of survival from 7 ± 1% to 18 ± 2% (82 dph; regression, P = 4*10,7). In halibut, the survival rate decreased from 57 ± 9% to 22 ± 7% as the inclusion of protein in the form of hydrolysate increased from 0 to 450 g kg,1 (119 dpff; regression, P = 8*10,5). Growth was not affected in any of the species. Results in specific activities of the intestinal enzymes leucine aminopeptidase (LAP) and alkaline phospatase (AP) supported the results in survival in halibut and partly also in cod, by showing increased activities in groups with increased survival (anova, P < 0.05). The lower optimal level of hydrolysed protein in halibut than in cod is suggested mainly because of a slower feeding practice in halibut, which allows more extensive nutrient leaching before ingestion. [source] Comparison of dietary phospholipids and neutral lipids: effects on gut, liver and pancreas histology in Atlantic cod (Gadus morha L.) larvaeAQUACULTURE NUTRITION, Issue 1 2009P.-A. WOLD Abstract The aim of the present study was to compare effects of dietary n-3 highly unsaturated fatty acids (HUFA) being incorporated in the phospholipid (PL) or in the neutral lipid (NL) fraction of the larval feed, on larval growth and histology of digestive organs in Atlantic cod (Gadus morhua L.) larvae. Three isoproteic and isolipidic diets, labelled according to the percentage of n-3 docosahexaenoic acid and eicosapentaenoic acid contained in NL1 or in PL1 and PL3 of the diets, were fed to cod larvae from 17 days post hatching (dph) to 45 dph. In the liver, hepatocytes and their nuclei were smaller in NL1 larvae compared with the PL larvae; the mitochondrial membrane structures were less dense and the amount of lipids observed in the liver was significantly higher in NL1 larvae compared with the PL3 larvae. The liver and gut size was related to larval size, with no differences between the larval groups. The results demonstrated that the essential fatty acids were more beneficial for cod larvae when they were incorporated in the dietary polar PL rather than in the NL, and that the n-3 HUFA requirements in cod larvae is possibly higher than that in the PL1 diet. [source] Application of prospective probionts at early stages of Atlantic cod (Gadus morhua L.) rearingAQUACULTURE RESEARCH, Issue 10 2010Hélène L Lauzon Abstract This work aimed at validating the use of two prospective probionts (Arthrobacter sp. and Enterococcus sp.) at early stages of cod (Gadus morhua L.) rearing. Ova at late post-fertilized stage and larvae during their first 4 weeks of life were bathed with both probionts, isolated previously from the cod-rearing environment. This treatment was compared with groups fed rotifers supplemented with a commercial probiotic (Remus®) and those untreated. Microbiological analyses (total viable counts, presumptive Vibrio and lactic acid bacteria) were performed in rearing systems and larval survival, growth and development were assessed. Larval development was evaluated by proteolytic activity of larval lysates and immunological analysis of important proteins: apolipoprotein A-I, haemoglobin, C-reactive protein, C3 and cod serum proteins. Bacterial bathing led to a significantly higher larval weight, length and culturable microbial load in larval gastrointestinal (GI) tract when compared with the control and Remus groups. Development occurred earlier in bathed larvae. However, their survival was negatively affected compared with the control group, but was significantly higher than for the Remus group. The non-pathogenicity of both probionts was demonstrated by intraperitoneal injection of 13 g cod juveniles. The results suggest that Arthrobacter and Enterococcus probionts affected the larval GI microbiota and contributed to growth, development and digestion, either directly or indirectly. [source] Electrical stunning of farmed Atlantic cod Gadus morhua L.: a comparison of an industrial and experimental methodAQUACULTURE RESEARCH, Issue 8 2010Hanne Digre Abstract An industrial and experimental electrical method for stunning farmed Atlantic cod in air and seawater (SW), respectively, were compared. The impacts of sedation with AQUI-SÔ and exercise to exhaustion before electrical stunning were also assessed to monitor the possible depletion of rested muscle energy levels by electrical stunning. Stress (blood glucose, haematocrit, muscle pH, muscle excitability, high-energy phosphates and rigor mortis) and flesh quality (fillet texture, colour, liquid leakage (LL), gaping, residual blood and K -value) were assessed. For the industrial stunning method, an average of 41 V, 0.2 A dc was applied to individual cod for 18,27 s. For the SW method, a bipolar square wave current (170 Hz, 33% duty cycle) was applied for 5 s. After stunning, recovery was prevented by exsanguination in chilled SW. There were no differences (P>0.05) between the two stunning methods except for a higher ultimate fillet pH for cod stunned in air 8 days postmortem. Exercise before stunning depleted muscle energy levels at slaughter, increased LL and fillets had redder and darker flesh after storage on ice for 8 days. Electrical stunning (in air) of AQUI-SÔ -treated fish partly depleted muscle energy levels (pH 7.3, ATP 18.7 ,mol g,1, PCr 70.1 ,mol g,1). However, flesh quality was not affected. Unless pre-rigor filleting is the chosen processing strategy, electrical stunning of cod seems to be a promising stunning method. [source] Lactic acid bacteria vs. pathogens in the gastrointestinal tract of fish: a reviewAQUACULTURE RESEARCH, Issue 4 2010Einar Ringø Abstract Intensive fish production worldwide has increased the risk of infectious diseases. However, before any infection can be established, pathogens must penetrate the primary barrier. In fish, the three major routes of infection are the skin, gills and gastrointestinal (GI) tract. The GI tract is essentially a muscular tube lined by a mucous membrane of columnar epithelial cells that exhibit a regional variation in structure and function. In the last two decades, our understanding of the endocytosis and translocation of bacteria across this mucosa, and the sorts of cell damage caused by pathogenic bacteria, has increased. Electron microscopy has made a valuable contribution to this knowledge. In the fish-farming industry, severe economic losses are caused by furunculosis (agent, Aeromonas salmonicida spp. salmonicida) and vibriosis [agent, Vibrio (Listonella) anguillarum]. This article provides an overview of the GI tract of fish from an electron microscopical perspective focusing on cellular damage (specific attack on tight junctions and desmosomes) caused by pathogenic bacteria, and interactions between the ,good' intestinal bacteria [e.g. lactic acid bacteria (LAB)] and pathogens. Using different in vitro methods, several studies have demonstrated that co-incubation of Atlantic salmon (Salmo salar L.) foregut (proximal intestine) with LAB and pathogens can have beneficial effects, the cell damage caused by the pathogens being prevented, to some extent, by the LAB. However, there is uncertainty over whether or not similar effects are observed in other species such as Atlantic cod (Gadus morhua L.). When discussing cellular damage in the GI tract of fish caused by pathogenic bacteria, several important questions arise including: (1) Do different pathogenic bacteria use different mechanisms to infect the gut? (2) Does the gradual development of the GI tract from larva to adult affect infection? (3) Are there different infection patterns between different fish species? The present article addresses these and other questions. [source] Mercury comparisons between farmed and wild Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.)AQUACULTURE RESEARCH, Issue 10 2009L B Jardine Abstract Wild and farmed Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.) were collected to assess changes in mercury with size in wild vs. farmed fish. Mercury concentrations were compared with Health Canada and United States Environmental Protection Agency consumption guidelines. Lipid dilution of mercury was examined by comparing lipid-extracted (LE) and non-lipid-extracted (NLE) flesh samples in both farmed and wild fish. Mercury concentrations in the flesh and liver of farmed salmon were significantly lower than concentrations in wild salmon of similar fork length (P<0.001), possibly due to growth dilution in rapidly growing farmed fish. Mercury concentrations were higher in LE tissue compared with NLE (P<0.05), suggesting lipid dilution of mercury in farmed fish with a high lipid content. Farmed cod, which do not grow more rapidly than wild cod, did not have significantly different flesh and liver concentrations compared with wild cod of similar fork length (P>0.05). Between species of farmed fish, cod had significantly higher mercury concentrations than salmon (P<0.05), but neither farmed nor wild salmon mercury concentrations exceeded federal consumption guidelines. These results suggest that rapid growth rates and a high lipid content may play important roles in regulating concentrations of contaminants such as mercury. [source] Milt characteristics of diploid and triploid Atlantic cod (Gadus morhua L.)AQUACULTURE RESEARCH, Issue 10 2009Stefano Peruzzi Abstract The work compares the characteristics of milt produced by diploid and triploid Atlantic cod in terms of sperm motility, density, DNA content, seminal-fluid composition and the ability of sperm to fertilize the eggs. The mean track velocity (VCL) was higher in the sperm of diploid than in the triploid males at 20 s post-activation (p.a.; 124.04 ± 6.91 vs. 113.32 ± 6.32 ,m s,1), but not at 40 s p.a. No differences between ploidies were observed for the remaining sperm-motility descriptors as for spermatozoa density, spermatocrit or seminal fluid's variables like pH, osmolarity, Cl,, Na+, Ca2+ and K+ concentration. Triploid males produced aneuploid sperm cells (average 1.46n, range 1.2,1.6n) and the larvae generated from artificial crossings with diploid females showed abnormal morphology and did not survive to exogenous feeding. Plasma concentration of 11-ketotestosterone in sexually mature diploid and triploid males was similar (5.35 ± 1.54 vs. 4.82 ± 1.15 ng mL,1) and no differences were found in the ability of males of both ploidies to induce spawning when held in tanks with diploid females. The paper provides evidence of gametic sterility of triploid males and examines the use of triploid fish as a management option to address the issues of genetic containment of farmed cod alongside measures for securing present fish-farming technologies. [source] Sperm velocity influence paternity in the Atlantic cod (Gadus morhua L.)AQUACULTURE RESEARCH, Issue 2 2008Geir Rudolfsen First page of article [source] Whole-body corticosteroid and plasma cortisol concentrations in larval and juvenile Atlantic cod Gadus morhua L. following acute stressAQUACULTURE RESEARCH, Issue 13 2006William King V Abstract Methods were developed to assess whole-body immunoreactive corticosteroid concentrations (IRC) and plasma levels of cortisol in Atlantic cod subjected to several common, acute stressors. A measurable corticosteroid stress response was observed at the first sampling in whole bodies of 8-day post-hatch (dph) larvae. Two groups of juveniles (,5 and 30 g) were subjected to a 30 s net stressor and whole-body IRC and plasma cortisol levels were determined. Post-stressor IRC in smaller fish rose approximately 14-fold, peaked at 1 h, were sustained for 3,6 h and returned to pre-stressor levels within 24 h. Post-stressor plasma cortisol levels in larger fish rose approximately 18-fold, peaked at 0.5,1 h, were sustained for 1,3 h and then returned to near pre-stressor levels after 24 h. Immunoreactive corticosteroid concentrations appeared to remain elevated longer than plasma cortisol levels suggesting that steroids other than cortisol were contributing to total immunoreactivity in homogenates. Juveniles exposed to either a grading procedure or high density transport had maximal IRC and plasma cortisol levels within 90 min which returned to pre-stressor levels within 24,72 h. A reduction in water salinity (20 g L,1) did not moderate the corticosteroid response in juveniles. The results show that Atlantic cod respond to common, acute stressors in a manner similar to other teleosts. Whole-body homogenates can be used to identify changes in IRC in response to acute stress in cod with the caveat that recovery IRC may differ from plasma cortisol concentrations. [source] | ||||||||||