Growth Of Atlantic Salmon Research Articles

Effects of dietary reduced glutathione on the growth and antioxidant capacity of juvenile Atlantic salmon (Salmo salar)

Effects of dietary reduced glutathione on the growth and antioxidant capacity of juvenile Atlantic salmon (<i>Salmo salar</i>)

Context-dependent impact of an ectoparasite on early marine growth in Atlantic salmon

The impact of sea lice on post-smolt growth (PSG) was studied by comparing growth patterns in the scales of recaptured adult salmon originating from hatchery-reared smolts that were untreated or were previously treated for sea lice infestation during the years 2003–2014. Growth in the returning hatchery-reared fish was also compared to the growth of wild fish from the same smolt year class. PSG was greater in treated versus untreated fish in the early part of the time series, which was a period of low marine survival. However, the differentiation in PSG disappeared in the later portion of the time series, which coincided with a shift from low to higher marine survival. This transition was demarcated by the year 2009. During this later period, PSG correlated with the marine survival of salmon, whereas in the early period, this correlation was not evident. Wild fish had faster PSG than untreated hatchery fish throughout the study period, but had slower PSG than treated hatchery fish during the early part of the time series. The effects of sea lice alone cannot explain the observed shift in marine survival occurring in 2009. However, it seems evident that the effect of antiparasitic treatment was contingent on poor marine survival, showing that the impacts of parasites on the PSG of Atlantic salmon are context dependent.

Proactive avoidance behaviour and pace-of-life syndrome in Atlantic salmon.

Individuals in a fish population differ in key life-history traits such as growth rate and body size. This raises the question of whether such traits cluster along a fast-slow growth continuum according to a pace-of-life syndrome (POLS). Fish species like salmonids may develop a bimodal size distribution, providing an opportunity to study the relationships between individual growth and behavioural responsiveness. Here we test whether proactive characteristics (bold behaviour coupled with low post-stress cortisol production) are related to fast growth and developmental rate in Atlantic salmon, Salmo salar. Boldness was tested in a highly controlled two-tank hypoxia test were oxygen levels were gradually decreased in one of the tanks. All fish became inactive close to the bottom at 70% oxygen saturation. At 40% oxygen saturation level a fraction of the fish actively sought to avoid hypoxia. A proactive stress coping style was verified by lower cortisol response to a standardized stressor. Two distinct clusters of bimodal growth trajectories were identified, with fast growth and early smoltification in 80% of the total population. There was a higher frequency of proactive than reactive individuals in this fast-developing fraction of fish. The smolts were associated with higher post-stress plasma cortisol than parr, and the proactive smolts leaving hypoxia had significant lower post-stress cortisol than the stayers. The study demonstrated a link between a proactive coping and fast growth and developmental ratio and suggests that selection for domestic production traits promotes this trait cluster.

The importance of exercise: Increased water velocity improves growth of Atlantic salmon in closed cages

There is increasing concern about Norwegian salmon farming and the possible environmental impacts from sea lice, escaped fish and release of toxic chemicals and organic emissions to the coastal waters. Closed containment systems (CCS) have the potential to eliminate the problems with sea lice and to reduce escapes and emissions. When closing the cages, water volumes and velocity are regulated and the identification of optimal current velocities for growth and fish welfare from sea transfer to harvest size becomes necessary. This study describes two trials with LOW (0.10–0.27 BL/s) and MODERATE (0.36–0.63 BL/s) water velocity on performance of post-smolt Atlantic salmon in CCS. In trial 1 (168 days, 10.9 °C, fish size: 884–3007 g and 41.5–59.0 cm), round weight increased with 219 g (p = .012) and condition factor with 0.11 (p = .016) in the MODERATE group compared with LOW group. The MODERATE group obtained specific growth rate (SGR) of 0.76 and thermal growth coefficient (TGC) of 2.75, compared to 0.72 and 2.56 in the LOW group. MODERATE water velocity was also associated with higher relative heart size (RHS) (p = .016), higher liver index (HSI) (p = .005), increased fillet yield (p ≤ .001) and lower levels of cathepsin activity in muscle tissue. In trial 2 (46 days, 7.1 °C, fish size: 327–482 g and 29.9–33.7 cm), round weight increased with 52 g (p = .019) and condition factor with 0.05 (p = .009) in the MODERATE group compared with LOW group. The MODERATE group obtained SGR of 0.77 and TGC of 2.68, compared to SGR of 0.60 and TGC of 2.02 in the LOW group. No significant difference was observed in white muscle cell hyperplasia, measured as the proportion of small (< 20 μm diameter) muscle fibres (p = .145). Both trials showed only minor differences in slaughter yield, fillet quality (protein, fat, water) and mortality. The present study shows that moderate water velocity (0.36–0.63 BL/s) is favourable for growth rates for Atlantic salmon during the entire on-growing period in CCS. Effects on a broader range of metabolic variables and welfare indicators were also documented.

Growth, immune response, antioxidant capability, and disease resistance of juvenile Atlantic salmon (Salmo salar L.) fed Bacillus velezensis V4 and Rhodotorula mucilaginosa compound

A feeding trial of 62 days was conducted to investigate the effects of dietary administration of a probiotics compound consisting of Bacillus velezensis V4 CGMCC 10149 and Rhodotorula mucilaginosa CGMCC 1013 on growth, immune response, antioxidant capability, and disease resistance of juvenile Atlantic salmon (Salmo salar L.) reared in a recirculating aquaculture system (RAS). Atlantic salmon were distributed in four equal groups, each with three replicates, which received one of the following experimental diets: Control (non-supplemented diet); T1 (B. velezensis V4 5 × 106 CFU g−1, R. mucilaginosa 5 × 107 CFU g−1), T2 (B. velezensis V4 1.5 × 107 CFU g−1, R. mucilaginosa 1.5 × 108 CFU g−1), and T3 (B. velezensis V4 2.5 × 107 CFU g−1, R. mucilaginosa 2.5 × 108 CFU g−1). Administration of the probiotics compound had significant effects on growth performance, feed utilization, immune response, and antioxidant capability of Atlantic salmon, and mortality was significantly reduced (P < 0.05). After the feeding trial, fish were challenged with Aeromonas salmonicida (A. salmonicida) and cumulative mortality was recorded for the next 7 days. The cumulative mortality was lower in Atlantic salmon fed with the probiotics compound, especially in the T1 group, compared to the control. These results demonstrated that multi-probiotics had beneficial effects as an antibiotic replacer in terms of growth performance, non-specific immune responses and disease resistance in salmon. The present study demonstrated B. velezensis V4 and R. mucilaginosa compound as a beneficial dietary probiotics for juvenile Atlantic salmon reared in a RAS with the capability of improving growth performance and enhancing disease resistance by immunomodulation.

Effects of ocean acidification on salinity tolerance and seawater growth of Atlantic salmon Salmo salar smolts.

Human activity has resulted in increasing atmospheric carbon dioxide (CO2 ), which will result in reduced pH and higher levels of CO2 in the ocean, a process known as ocean acidification. Understanding the effects of ocean acidification (OA) on fishes will be important to predicting and mitigating its consequences. Anadromous species such as salmonids may be especially at risk because of their rapid movements between fresh water and seawater, which could minimize their ability to acclimate. In the present study, we examine the effect of future OA on the salinity tolerance and early seawater growth of Atlantic salmon Salmo salar smolts. Exposure to 610 and 1010 μatm CO2 did not alter salinity tolerance but did result in slightly lower plasma chloride levels in smolts exposed to seawater compared with controls (390 μatm). Gill Na+ -K+ -ATPase activity, plasma cortisol, glucose and haematocrit after seawater exposure were not altered by elevated CO2 . Growth rate in the first 2 weeks of seawater exposure was greater at 1010 μatm CO2 than under control conditions. This study of the effects of OA on S. salar during the transition from fresh water to seawater indicates that elevated CO2 is not likely to affect osmoregulation negatively and may improve early growth in seawater.

Chronic exposure to increased water temperature reveals few impacts on stress physiology and growth responses in juvenile Atlantic salmon

Fish are subjected to a variety of stressors under common cage aquaculture conditions. While short-term exposure to a stressor often results in an adaptive response to cope with stress, repeated and/or chronic exposure to stress can result in negative impacts on fish welfare and production. In fish, little is known about the impact of long-term exposure to stressors, including elevated water temperature. In this study we examined and developed temporal response profiles of physiological indicators of stress and growth in juvenile Atlantic salmon (Salmo salar) exposed to 12 °C, 16 °C, and 20 °C for 99 days. Five times throughout the study we quantified plasma cortisol, glucose and cholesterol levels, and growth. Fish body mass and fork length were not significantly different amongst temperatures after 99 days. Plasma cortisol was significantly elevated at 16 °C when comparing day 8 with 99, while at 12 °C plasma cortisol increased from day 1 to day 8, then returned to initial levels (day 1 and 8) after 99 days. Plasma glucose and cholesterol were not significantly different amongst the temperatures throughout the experiment. In addition, at the end of the experiment we quantified eye darkening, and identified the development of a bimodal growth distribution in all temperatures. Fish with a fork length ≤ 240 mm were categorised as lower mode (LM) and those with a fork length > 240 mm as in the upper mode (UM) of growth. Plasma cholesterol was significantly lower in the LM group in all three temperatures, but plasma cortisol and glucose levels did not differ between modes. Eye darkening also did not differ between modes, but increased significantly in the groups exposed to 16 °C and 20 °C when compared with 12 °C. This study showed a clear physiological stress response (elevated levels of cortisol) and eye darkening in fish maintained at 16 °C but not at 12 °C or 20 °C, suggesting that some aspects of the physiological responses available to deal with chronic stress are affected by temperature.

Modelling climate change effects on Atlantic salmon: Implications for mitigation in regulated rivers

Climate change is expected to alter future temperature and discharge regimes of rivers. These regimes have a strong influence on the life history of most aquatic river species, and are key variables controlling the growth and survival of Atlantic salmon. This study explores how the future abundance of Atlantic salmon may be influenced by climate-induced changes in water temperature and discharge in a regulated river, and investigates how negative impacts in the future can be mitigated by applying different regulated discharge regimes during critical periods for salmon survival. A spatially explicit individual-based model was used to predict juvenile Atlantic salmon population abundance in a regulated river under a range of future water temperature and discharge scenarios (derived from climate data predicted by the Hadley Centre's Global Climate Model (GCM) HadAm3H and the Max Plank Institute's GCM ECHAM4), which were then compared with populations predicted under control scenarios representing past conditions. Parr abundance decreased in all future scenarios compared to the control scenarios due to reduced wetted areas (with the effect depending on climate scenario, GCM, and GCM spatial domain). To examine the potential for mitigation of climate change-induced reductions in wetted area, simulations were run with specific minimum discharge regimes. An increase in abundance of both parr and smolt occurred with an increase in the limit of minimum permitted discharge for three of the four GCM/GCM spatial domains examined. This study shows that, in regulated rivers with upstream storage capacity, negative effects of climate change on Atlantic salmon populations can potentially be mitigated by release of water from reservoirs during critical periods for juvenile salmon.

Size‐dependent prey availability affects diet and performance of predatory fish at sea: a case study of Atlantic salmon

AbstractIdentifying factors determining the performance of individuals is an essential part of resolving what drives population dynamics. For species undergoing ontogenetic shifts in resource and habitat use, this entails assessing individual performance in all habitats used. Whereas survival and growth of anadromous Atlantic salmon, Salmo salar L., in its juvenile, river habitat are known to depend on size‐dependent foraging and food availability, individual performance of salmon in the growth habitat out at sea is commonly explained only by abiotic factors. Still, individuals undergo this habitat shift to grow large, suggesting performance should be food‐dependent also in the growth habitat. Because fish communities are highly size‐structured, the link between predators and their prey may depend on their respective body sizes. Here, we study whether the performance of Baltic Sea salmon in its growth habitat is food‐ and size‐dependent, by combining extensive diet and body size data of Baltic salmon with spatially resolved monitoring data on abundance and size distribution of their main prey, herring, Clupea harengus L., and sprat, Sprattus sprattus L. We found that both the species and size composition of prey in the diet varied with salmon body size. By accounting for this size‐dependent predation and the spatially varying size distribution of prey species, we could explain the variation in salmon diet composition among salmon individuals in different Baltic Sea basins and of different length. The proportion of sprat in diet of salmon was better explained by size‐specific prey availability (SSP) than total prey biomass, especially for small salmon. Further, salmon body condition increased with SSP, whereas total prey biomass could not explain variation in the condition of salmon. These findings demonstrate that food‐ and size‐dependent processes indeed can influence the performance of anadromous fish also in large marine systems. Thus, we argue that consideration of these processes, stretching across habitats, is important for understanding performance and dynamics of predatory fish in open aquatic systems, as well as for successful management of species such as Atlantic salmon.

Strain-specific survival and growth of juvenile Atlantic salmon in Central New York tributaries

Abstract Reintroduction of Atlantic salmon Salmo salar in the Lake Ontario watershed represents a historical challenge for fisheries managers dating to the late 1800s. To assess the feasibility for reintroduction, strain-specific differences in survival and growth was evaluated in central New York tributaries in 2014 and 2015. Fry of Lake Memphremagog and Sebago Lake strains were stocked at target densities of 100 fry/100 m 2 in tributaries within the Ontario Drumlins and Fish Creek regions. Salmon abundance, density, and survival was estimated at each stocking location. Standardized mass-specific growth rate ( G s ) and absolute growth in length ( G L ) of age-0 parr and age-1 pre-smolts was evaluated with two-way analysis of variance. For both strains, survival was largely site-dependent in the Drumlins region and stream-dependent in the Fish Creek region. The Lake Memphremagog strain exhibited faster growth, suggesting that physiological adaptations of this strain make it a more suitable candidate for reintroduction in the region when the source is available. However, limited availability of the Lake Memphremagog strain may direct future efforts to employ the more widely-evaluated and available Sebago Lake strain.

Sex steroid production associated with puberty is absent in germ cell-free salmon

In all vertebrates studied so far, germ cells are not required for pubertal maturation of the gonadal steroidogenic system, subsequent development of secondary sex characteristics and reproductive behavior. To explore if the absence of germ cells affects puberty or growth in Atlantic salmon, germ cell-free (GCF), dnd knockout and wild type (WT) postsmolts were stimulated to enter puberty. No GCF fish entered puberty, whereas 66.7% (males) and 30% (females) WT fish completed or entered puberty, respectively. Expression of genes related to steroidogenesis (star, cyp17a1, cyp11β, cyp19a1a), gonadal somatic cells (insl3, amh, igf3), oocytes (bmp15), gonadotropin receptors (fshr, lhcgr), and pituitary gonadotropic cells (fshb, lhb, gnrhr4) showed an immature status and failure to up-regulate gonadal sex steroid production in male and female GCF fish was also reflected in low or undetectable plasma sex steroids (11-ketotestosterone, estradiol-17β and testosterone). A gender difference (high in females, low in males) was found in the expression of star and cyp17a1 in GCF fish. No clear difference in growth was detected between GCF and immature WT fish, while growth was compromised in maturing WT males. We demonstrate for the first time in a vertebrate that germ cells are required for pubertal activation of the somatic steroidogenic cells.

The effect of continuous light at low temperatures on growth in Atlantic salmon reared in commercial size sea pens

The aim of this study was to investigate the effect of continuous light of different duration, applied from late autumn to spring in the second year of the production cycle, on the production performance of Atlantic salmon in Northern Norway. The underlying hypothesis is that the introduction of continuous light (LL) superimposed on the natural light before December (the preferred continuous light regime in Northern Norway) could enhance growth and inhibit maturation in the subsequent year. To test this, two large, commercial scale experiments were performed [Experiment 1 in 2014 at 69.47°N, 18.26°E, and Experiment 2 in 2015 at 69.80°N, 19.42°E] where salmon of initial size of 1–1.5kg were subjected to LL at different time points during the period between 11 November and 13 December, and reared under LL until 31 March the following year. In Experiment 1 the water temperature at 6m depth ranged between 6.7°C in November and 3.6°C in March and in Experiment 2 the water temperature at 6m depth ranged between 8.3°C in November and 3.6°C in March and 6.8°C in May 2016. Before and after the period with LL, all fish were reared under natural light. Growth was improved by 13–20% in the early exposed groups (15 Nov and 11 Nov) compared to the late exposed groups (13 Dec.). No maturation was seen in the experimental groups at slaughter (Exp. 1: July–September 2015, Exp. 2: May 2016). Vertebra deformities did not differ between the early and late exposed groups suggesting that continuous light promotes growth at lower temperatures, while supporting normal vertebra development. Only minor differences in flesh texture (measured as differences in cathepsin L+B activity) were found in both experiments. It is concluded that a considerable growth benefit may be achieved by exposing Atlantic salmon to continuous light from early November in their first year in seawater, i.e. one month earlier than presently used by the salmon farming industry in Northern Norway.

Genetic background and embryonic temperature affect DNA methylation and expression of myogenin and muscle development in Atlantic salmon (Salmo salar).

The development of ectothermic embryos is strongly affected by incubation temperature, and thermal imprinting of body growth and muscle phenotype has been reported in various teleost fishes. The complex epigenetic regulation of muscle development in vertebrates involves DNA methylation of the myogenin promoter. Body growth is a heritable and highly variable trait among fish populations that allows for local adaptations, but also for selective breeding. Here we studied the epigenetic effects of embryonic temperature and genetic background on body growth, muscle cellularity and myogenin expression in farmed Atlantic salmon (Salmo salar). Eggs from salmon families with either high or low estimated breeding values for body growth, referred to as Fast and Slow genotypes, were incubated at 8°C or 4°C until the embryonic ‘eyed-stage’ followed by rearing at the production temperature of 8°C. Rearing temperature strongly affected the growth rates, and the 8°C fish were about twice as heavy as the 4°C fish in the order Fast8>Slow8>Fast4>Slow4 prior to seawater transfer. Fast8 was the largest fish also at harvest despite strong growth compensation in the low temperature groups. Larval myogenin expression was approximately 4–6 fold higher in the Fast8 group than in the other groups and was associated with relative low DNA methylation levels, but was positively correlated with the expression levels of the DNA methyltransferase genes dnmt1, dnmt3a and dnmt3b. Juvenile Fast8 fish displayed thicker white muscle fibres than Fast4 fish, while Slow 8 and Slow 4 showed no difference in muscle cellularity. The impact of genetic background on the thermal imprinting of body growth and muscle development in Atlantic salmon suggests that epigenetic variation might play a significant role in the local adaptation to fluctuating temperatures over short evolutionary time.

Effects of light source and intensity on sexual maturation, growth and swimming behaviour of Atlantic salmon in sea cages

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 9:193-204 (2017) - DOI: https://doi.org/10.3354/aei00224 Effects of light source and intensity on sexual maturation, growth and swimming behaviour of Atlantic salmon in sea cages Tom Johnny Hansen*, Per Gunnar Fjelldal, Ole Folkedal, Tone Vågseth, Frode Oppedal Institute of Marine Research, 5984 Matredal, Norway *Corresponding author: tomh@imr.no ABSTRACT: We investigated how highly efficient LED light sources may be used in Atlantic salmon cage farming. Specifically, we tested the incidence of sexual maturation and growth patterns in autumn sea-transferred Atlantic salmon Salmo salar L. during their second sea winter given continuous artificial light (LL) (between 13 January and 18 June) of 5 different intensities using LED sources, compared to a single intensity provided by a metal halide (MH) source or a control treatment of natural light (NL). Growth effects were independent of light source, but increased with irradiance. We propose a model wherein sufficiently high irradiance from the artificial light source will give a long day signal throughout late winter and spring, an intermediate irradiation will give a long day signal until it is outcompeted by the seasonal increase in natural light, and an irradiance that is always below the threshold will not be perceived as different from natural light. Sexual maturation in males (6.1% under NL) was evenly arrested at all intensities, and swimming activity at night increased during winter in lit groups. We conclude that LED lamps may replace MH sources at similar intensity. Reducing the light irradiance of the superimposed light reduced the growth-stimulating effect, but all irradiances reduced the incidence of sexual maturation. KEY WORDS: Salmo salar · Photoperiod · Salmonid aquaculture · Cage environment Full text in pdf format PreviousNextCite this article as: Hansen TJ, Fjelldal PG, Folkedal O, Vågseth T, Oppedal F (2017) Effects of light source and intensity on sexual maturation, growth and swimming behaviour of Atlantic salmon in sea cages. Aquacult Environ Interact 9:193-204. https://doi.org/10.3354/aei00224 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 9. Online publication date: June 20, 2017 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2017 Inter-Research.

Распределение, питание и рост искусственно выращенной молоди семги (Salmo salar L.) после выпуска на участки рек с разными абиотическими условиями

Распределение, питание и рост искусственно выращенной молоди семги (Salmo salar L.) после выпуска на участки рек с разными абиотическими условиями

Skeletal muscle protease activities in the early growth and development of wild Atlantic salmon (Salmo salar L.).

Growth-related dynamics of intracellular protease activities in four year classes of the Atlantic salmon (Salmo salar L. 1758) parr and smolts inhabiting salmon rivers of northwestern Russia (the White Sea basin) were studied. Cathepsin B, cathepsin D, proteasome, and calpain activities in the skeletal muscles of salmon were assessed to investigate their relative contribution to the total protein degradation as well as to young fish growth process. It was confirmed that calpain activity dominates in salmon muscles while proteasome plays a minor role, in contrast to terrestrial vertebrates. Calpain and proteasome activities were maximal at the early post-larval stage (in parrs 0+) and declined with age (parrs 1+ through 2+) dropping to the lowest level in salmon smolts. Annual growth increments and proteolytic activities of calpains and proteasome in the muscles of salmon juveniles changed with age in an orchestrated manner, while lysosomal cathepsin activities increased with age. Comparing protease activities and growth increments in salmon parr and smolts we suggested that the partial suppression of the protein degradation could be a mechanism stimulating efficient growth in smoltifying salmon. Growth and smoltification-related dynamics of protease activities was quite similar in salmon populations from studied spawning rivers, such as Varzuga and Indera; however, some habitat-related differences were observed. Growth increments and protease activities varied in salmon parr 0+ (but not on later ages) inhabiting either main rivers or small tributaries apparently due to habitat difference on the resources for fish growth.

Ploidy elicits a whole-genome dosage effect: growth of triploid Atlantic salmon is linked to the genetic origin of the second maternal chromosome set

BackgroundThe Atlantic salmon aquaculture industry is investigating the feasibility of using sterile triploids to mitigate genetic interactions with wild conspecifics, however, studies investigating diploid and triploid performance often show contrasting results. Studies have identified dosage and dosage-compensation effects for gene expression between triploid and diploid salmonids, but no study has investigated how ploidy and parent-origin effects interact on a polygenic trait in divergent lines of Atlantic salmon (i.e. slow growing wild versus fast growing domesticated phenotype). This study utilised two experiments relating to the freshwater growth of diploid and triploid groups of pure wild (0% domesticated genome), pure domesticated (100% domesticated genome), and F1 reciprocal hybrid (33%, 50% or 66% domesticated genome) salmon where triploidy was either artificially induced (experiment 1) or naturally developed/spontaneous (experiment 2).ResultsIn both experiments, reciprocal hybrid growth was influenced by the dosage effect of the second maternal chromosome, with growth increasing as ploidy level increased in individuals with a domesticated dam (from 50% to 66% domesticated genome), and the inverse in individuals with a wild dam (from 50% to 33% domesticated genome).ConclusionsWe demonstrate that the combined effect of ploidy and parent-origin on growth, a polygenic trait, is regulated in an additive pattern. Therefore, in order to maximise growth potential, the aquaculture industry should consider placing more emphasis on the breeding value of the dam than the sire when producing triploid families for commercial production.

Land-based growth of Atlantic salmon (Salmo salar) and consumers’ acceptance

Atlantic salmon (Salmo salar) is currently the highest valued species grown in Europe. The industry has been on the frontline of public concerns regarding sustainability which has increased the use of recirculating aquaculture systems (RAS). Salmon has changed from a luxury product to global commodity. Nevertheless, food products need to meet consumers demand for the industry to be successful. Descriptive sensory tests present a sophisticated tool for the comparison of product prototypes to understand consumer responses in relation to sensory attributes. Aquaculture is being promoted in the Basque region with the aim of creating a sustainable and complementary economic activity to the fishing and seafood sectors. Here, RAS and salmon have been prioritized as a potential technology and species respectively. Both salmon's growth and a hedonic evaluation of the final product's consumer acceptance and purchasing intention were studied. One thousand five hundred salmon individuals were grown for 497 days at two different thermal regimes in two pilot-scale RAS units using partial reuse water recirculation systems. Growth rates were significantly different for both temperature regimes during the second summer season; some compensatory growth patterns were observed that followed the timing of the natural thermal regime. No significant differences were observed at sensorial level between fillet samples from the present study and salmon from Denmark. Consumer's high level of acceptance and positive product purchasing intention reflect the possibility of locally marketing RAS grown salmon. This study refers to the first technical attempt at salmon in land-based aquaculture systems in northern Spain.

Choline supplementation increased total body lipid gain, while surplus methionine improved growth and amino acid retention in adult Atlantic salmon (Salmo salar)

Choline supplementation increased total body lipid gain, while surplus methionine improved growth and amino acid retention in adult Atlantic salmon (<i>Salmo salar</i>)

The effects of increasing dietary levels of soy protein concentrate (SPC) on the immune responses and disease resistance (furunculosis) of vaccinated and non-vaccinated Atlantic salmon (Salmo salar L.) parr

Juvenile salmon, with an initial weight of 9 g, were fed three experimental diets, formulated to replace 35 (SPC35), 58 (SPC58) and 80 (SPC80) of high quality fishmeal (FM) with soy protein concentrate (SPC) in quadruplicate tanks. Higher dietary SPC inclusion was combined with increased supplementation of methionine, lysine, threonine and phosphorus. The experiment was carried out for 177 days. On day 92 salmon in each tank were bulk weighed. Post weighing eighty salmon from each tank were redistributed in two sets of 12 tanks. Salmon from the first set of tanks were vaccinated, while the second group was injected with phosphate buffer saline (PBS). Salmon were sampled on day 92 (pre-vaccination), day 94 (2 days post vaccination [dpv]/PBS injection [dpPBSinj]) and day 154 (62 dpv/dpPBSinj) of the trial for the assessment of their immune responses, prior to the performance of salmon bulk weights for each tank. On day 154, fish from each tank were again bulk weighed and then seventeen salmon per tank were redistributed in two sets of twelve tanks and intra-peritoneally infected with Aeromonas salmonicida. At Day 154, SPC80 demonstrated lower performance (weight gain, specific growth rate and thermal growth coefficient and feed conversion ratio) compared to SPC35 salmon. Reduced classical and total complement activities for salmon fed diets with over 58% of protein from SPC, were demonstrated prior to vaccination. Reduced alternative complement activity was detected for both SPC58 and SPC80 salmon at 2 dpv and for the SPC80 group at 62 dpv. Total and classical complement activities demonstrated no differences among the dietary groups after vaccination. Numerical increases in classical complement activity were apparent upon increased dietary SPC levels. Increased phagocytic activity (% phagocytosis and phagocytic index) was exhibited for the SPC58 group compared to SPC35 salmon at 62 dpPBSinj. No differences in serum lysozyme activity, total IgM, specific antibodies, protein, glucose and HKM respiratory burst were detected among the dietary groups at any timepoint or state. Mortalities as a result of the experimental infection only occurred in PBS-injected fish. No differences in mortality levels were demonstrated among the dietary groups. SPC58 diet supported both good growth and health in juvenile Atlantic salmon while SPC80 diet did not compromise salmon’ immunity or resistance to intraperitoneally inflicted furunculosis.