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Growth performance (average salmon weight) from fry stage to market-size for the three Atlantic salmon cohorts evaluated. Day 1 of the life cycle is equivalent with egg hatch.
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There is interest in culturing Atlantic salmon Salmo salar to market-size in land-based, closed containment systems that use recirculation aquaculture systems (RAS), as this technology often enables facilities to locate near major markets, obtain permits, exclude obligate pathogens, and/or reduce environmental impacts. Use of land-based RAS to inte...
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... St. John river salmon SJR salmon grew from 0.34 to 4.2 kg in 9.8 months (393 g/month) in the near-commercial-scale RAS ( Fig. 2). At this time, harvest of market size (4.2 kg mean weight) salmon began. Salmon continued to grow during the 10-week harvest period. By the end of the har- vest cycle, mean fish weight was 4.7 kg ( Fig. 2) and corresponding CF was 1.83 ± 0.03. Thermal growth coefficient from time of stock- ing to first harvest was 2.01. Economic FCR, ...Context 2
... St. John river salmon SJR salmon grew from 0.34 to 4.2 kg in 9.8 months (393 g/month) in the near-commercial-scale RAS ( Fig. 2). At this time, harvest of market size (4.2 kg mean weight) salmon began. Salmon continued to grow during the 10-week harvest period. By the end of the har- vest cycle, mean fish weight was 4.7 kg ( Fig. 2) and corresponding CF was 1.83 ± 0.03. Thermal growth coefficient from time of stock- ing to first harvest was 2.01. Economic FCR, which accounted for all feed delivered to the fish over the grow-out trial duration, was 1.09. Maximum biomass density was 35 kg/m 3 , which is relatively low, but was intentionally kept at <40 kg/m 3 ...Context 3
... salmon grew from 0.75 to 4.1 kg in 8.7 months (386 g/month) in the commercial-scale RAS (Fig. 2). Harvests began when CS1 salmon reached a mean weight of 4.1 kg and contin- ued thereafter for the next 4 months. Remaining salmon continued to grow during the harvest period and achieved a mean weight of 5.7 kg with a CF of 1.84 ± 0.06 by the end of the trial. Thermal growth coefficient from time of stocking to first harvest was 1.65; ...Context 4
... a mean water temperature of 15-16 • C. CS2 grew at a similar rate (413 g/month) to first harvest at which time the fish were selectively top-graded at 4.9 kg. There- after, comparable growth data was not as readily available for CS2 as a result of the top grading harvest technique. Growth data during the grow-out period was approximately linear (Fig. 2) for all three cohorts, suggesting that cumulative weight gain (grams/day) was relatively independent of fish cohort/strain, fish size, and maximum biomass density, which ranged from 35 kg/m 3 for SJR to as high as 118 kg/m 3 for CS2. Atlantic salmon cultured in the commercial- scale RAS achieved harvest size approximately 2 years from ...Context 5
... age at which the three cohorts reached market-size were: 1) targeted size at harvest and 2) growth rate from approximately 300-450 days post hatch, the period immediately following smoltification. Post-smolt salmon appeared to be more fragile during this period, possibly due to lack of salt water exposure; and growth was relatively inconsis- tent (Fig. 2). CS1 salmon did not encounter a significant growth delay, but the growth rates of SJR and CS2 salmon appeared to be inhibited during this period. CS2 and SJR salmon encountered a rel- atively mild bacterial gill disease infection and fungus, respectively, during this production phase which likely contributed to reduced growth ...Context 6
... and CS2 salmon were cultured at maximum densities of 100 and118 kg/m 3 , respectively; these biomass densities did not appear to negatively impact growth (Fig. 2), survival, and other key performance metrics. Turnbull et al. (2008) considered a range of parameters, such as the aforementioned performance variables, as best indicators for fish welfare. While it is difficult to assess welfare in relation to stocking density based on behavioral indicators alone ( Turnbull et al., 2008), the Atlantic ...Similar publications
There is increasing investment in and use of land-based recirculating aquaculture systems (RAS) to produce market-size Atlantic salmon (Salmo salar) despite limited understanding of economic feasibility at commercial scale. High incidence of early maturing fish in RAS growout is one obstacle to profitability for this production method. Well-defined...
Production of Atlantic salmon smolts in recirculation aquaculture systems (RAS) is growing, and novel production protocols using continuous light in RAS are being implemented in the industry. In the present study, Atlantic Salmon parr were exposed to either a traditional protocol (short‐day winter signal [12:12 L:D] for 6 weeks) or to continuous li...
Recirculating aquaculture systems (RAS) are efficient at solid waste capture and collection but generate a concentrated waste stream. Anaerobic digestion (AD) could be one potential treatment option for RAS facilities. However, the concentration of organic matter in the sludge can significantly affect the biogas quality from AD. This study evaluate...
A key challenge in recirculating aquaculture systems (RAS) is the accumulation of particulate organic matter, especially the fine and colloidal fraction due to low removal efficiency of today's technology. The supply of organic matter is typically the limiting resource determining the carrying capacity (CC) of heterotrophic bacteria in the system....
Hydrogen sulphide (H2S) is a gas that affects mucosal functions in mammals. However, its detrimental effects are less understood in fish despite being known to cause mass mortality. Here we used explant models to demonstrate the transcriptional responses of Atlantic salmon (Salmo salar) mucosa to the sulphide donor sodium hydrosulphide (NaHS). The...
Citations
... Recirculating aquaculture system (RAS) was developed as a more environmentally friendly method to produce food (FAO 2022). Its main appeal is to reduce the water requirement (Davidson et al. 2016) and a more flexible placement of facilities and easier treatment of wastewater, although good quality raw water is still a priority. Water recirculation includes multiple water treatment steps, before leading water back to rearing tanks (Badiola, Mediola, and Bostock 2012). ...
Aquaculture is becoming increasingly important for the world's food production. Recirculating aquaculture system (RAS) has a reduced water requirement and better possibilities for waste handling. Unfortunately, off‐flavours can be formed in RAS and concentrate on fish flesh. Off‐flavour compounds cause earthy, musty or other unwanted flavours to fish flesh that consumers find objectionable. Typically, off‐flavours are removed by depurating the fish in clean water, but it often takes from days to weeks to fully remove these unwanted flavours that causes additional costs to fish producers. Therefore, reliable methods to reduce the need for depuration are needed. In this study, two methods were investigated for the removal of off‐flavours in RAS rearing rainbow trout Oncorhynchus mykiss: an advanced oxidation process (AOP) using a combination of ozone (O3) and hydrogen peroxide (H2O2), and a treatment with H2O2 alone. Two treatments (AOP and H2O2) and a control without oxidants were applied across nine identical experimental RASs for 8 h day⁻¹ over 10 days, and selected off‐flavour compounds in water and fish were analysed. In fish, the concentrations of GSM and MIB were on average 776 and 962 ng kg⁻¹ (AOP) and 688 and 919 ng kg⁻¹ (H2O2) compared to 1071 and 1205 ng kg⁻¹ in the controls. The results showed that intensive oxidant treatments reduced the off‐flavour concentrations in the recirculating water and in fish, which can potentially lead to reduced depuration time and production costs. Further optimization of the treatment is needed to improve off‐flavour removal efficiencies.
... This switch has significantly improved growth rates due to the manipulation of environmental conditions, as rather than try and replicate seasonal temperature fluctuations and photoperiods, modern recirculation aquaculture systems (RAS) generally keep fish on constant conditions of relatively high temperatures (10-16 • C) and 24 h daylength from first feeding (e.g. Davidson et al., 2016;Fossmark et al., 2021;Pino-Martinez et al., 2021;Ytrestøyl et al., 2023). This ensures high growth rates year-round and leads to fish being up to 1 kg within the first year of hatching. ...
... Some of the H 2 S-related mass mortalities in RAS in recent years have occurred in more saline environments. The industry has taken a higher salinity approach for production of salmon to avoid fungal outbreaks, mitigate stress effects of handling (Davidson et al., 2016), use rearing conditions with an osmolarity more similar to the fish internal osmolarity, thereby reducing the costs for osmoregulation (Ytrestøyl et al., 2020), and acclimatize the fish to a higher concentration of ions and minerals to prepare them for smoltification and transfer to the sea (Fossmark et al., 2021). As saline water contain more sulphate than freshwater, the risk for H 2 S production is higher in seawater RAS than in freshwater RAS (Letelier-Gordo et al., 2020;Plugge et al., 2011). ...
... On the downside of using membranes to remove sulphate from the intake water is also the removal of other ions, such as Ca 2+ , Mg 2+ (Sharrer et al., 2010). This will likely have an impact on fish performance, due to the generation of osmotic imbalances between the fish and the rearing water, and the lower capacity of the water to mitigate the toxicity of metals or pollutants ( Davidson et al., 2016;Fossmark et al., 2021;Ytrestøyl et al., 2020). Membrane technology is useful in removing particles and potentially pathogenic microorganisms from intake water (Fossmark et al., 2020;Mota et al., 2022;Wold et al., 2014;Yang et al., 2023). ...
... The aquaculture approach for Atlantic salmon involves alternations between industrial RAS and offshore cage culture. This approach has been successfully implemented in China (Dong et al., 2010;Yu et al., 2022) and around the globe (Bergheim et al., 2009;Davidson et al., 2016). In different phases of culture, fish exhibited different metabolomic profiles that are associated with cortisol synthesis and secretion and biosynthesis of cofactors in the brain of Atlantic salmon, and nucleotide metabolism in the skin during smoltification. ...
... For males, there were no differences in length between salmon caught in the open Baltic Sea and the ones at the river mouths (one-way ANOVAs, p > 0.05); for females these differences in length comparing salmon caught in the open Baltic Sea and individuals at the river mouths were significant (one-way ANOVAs, p < 0.05) except for individuals caught in Umeälven river mouth (one-way ANOVA, F 1,25 = 0.74, p = 0.399). Although smaller and in some cases significantly, salmon caught in the open Baltic were probably ready to migrate towards their natal rivers given their GSI values (Table 2) higher than GSI threshold for the onset of maturation in Atlantic salmon of 0.06 and 0.3 % defined by previous studies (( Peterson et al., 2005;Davidson et al., 2016;Martinez et al., 2023a;Martinez et al., 2023b)). Length of the fish also tended to vary somewhat between sampling occasions in each river but not significantly (one-way ANOVAs, p > 0.05), except for females in Drammen (one-way ANOVA, F 2,24 = 6.94, p = 0.004) and Driva rivers (one-way ANOVA, F 1,15 = 7.41, p = 0.016). ...
Thiamin is an essential water‐soluble B vitamin known for its wide range of metabolic functions and antioxidant properties. Over the past decades, reproductive failures induced by thiamin deficiency have been observed in several salmonid species worldwide, but it is unclear why this micronutrient deficiency arises. Few studies have compared thiamin concentrations in systems of salmonid populations with or without documented thiamin deficiency. Moreover, it is not well known whether and how thiamin concentration changes during the marine feeding phase and the spawning migration. Therefore, samples of Atlantic salmon (Salmo salar) were collected when actively feeding in the open Baltic Sea, after the sea migration to natal rivers, after river migration, and during the spawning period. To compare populations of Baltic salmon with systems without documented thiamin deficiency, a population of landlocked salmon located in Lake Vänern (Sweden) was sampled as well as salmon from Norwegian rivers draining into the North Atlantic Ocean. Results showed the highest mean thiamin concentrations in Lake Vänern salmon, followed by North Atlantic, and the lowest in Baltic populations. Therefore, salmon in the Baltic Sea seem to be consistently more constrained by thiamin than those in other systems. Condition factor and body length had little to no effect on thiamin concentrations in all systems, suggesting that there is no relation between the body condition of salmon and thiamin deficiency. In our large spatiotemporal comparison of salmon populations, thiamin concentrations declined toward spawning in all studied systems, suggesting that the reduction in thiamin concentration arises as a natural consequence of starvation rather than to be related to thiamin deficiency in the system. These results suggest that factors affecting accumulation during the marine feeding phase are key for understanding the thiamin deficiency in salmonids.
... As such, RAS may have the advantage of reducing water consumption, allowing more resilient farming techniques with a lower dependence on natural resources. In addition, being the reared animal isolated from the environment, they are less susceptible to pathogens and parasite coming from the wild (such as sea lice in salmon) and the risk of inbreeding with wild populations due to escapes is removed [9,10]. A typical water treatment plant of a RAS consists, in sequence, of a mechanical filter, a biological filter, a degasser, an oxygen enrichment unit and a disinfection unit [11]. ...
... It should be noted that the low-pressure mercury vapour lamp acts as a VUV source only if it is equipped with a special glass transparent to the radiation at such low wavelengths. The mechanism responsible for the degradation of GSM and MIB with VUV is not the direct photolysis of the off-flavour molecules, but the indirect degradation due to OH radicals formed from water according to Eq. (9). ...
... For commercial aquaculture to be successful, fish cohorts are required to grow rapidly and uniformly to what is considered a usable size at the minimum cost of resources and capital (Timmons et al., 2002). A well-informed feeding regimen can increase the likelihood of optimum growth, reduce costs, and decrease environmental impacts from waste outputs (Davidson et al., 2016). To implement such a feeding regimen, we require information on environmental conditions and fish cohort properties, such as total biomass, growth rates, feed efficiency and body size distribution (Chary et al., 2022;Føre et al., 2018;Lugert et al., 2016). ...
... Ration size is one of the most influential feeding regime factors and is readily manipulated to enhance the likelihood of optimum growth as well as lower costs and environmental impact from uneaten pellets or waste outputs (Davidson et al., 2016). This study on the growth performance of a cohort of all-female, juvenile king salmon fed three rations of 60% (60S), 80% (80S) and 100% satiation (100S) for 276 days demonstrates that there are large differences in mean and individual-level growth performance under different feeding regimes. ...
Fed aquaculture is one of the fastest‐growing and most valuable food production industries in the world. The efficiency with which farmed fish convert feed into biomass influences both environmental impact and economic revenue. Salmonid species, such as king salmon (Oncorhynchus tshawytscha), exhibit high levels of plasticity in vital rates such as feed intake and growth rates. Accurate estimations of individual variability in vital rates are important for production management. The use of mean trait values to evaluate feeding and growth performance can mask individual‐level differences that potentially contribute to inefficiencies. Here, the authors apply a cohort integral projection model (IPM) framework to investigate individual variation in growth performance of 1625 individually tagged king salmon fed one of three distinct rations of 60%, 80%, and 100% satiation and tracked over a duration of 276 days. To capture the observed sigmoidal growth of individuals, they compared a nonlinear mixed‐effects (logistic) model to a linear model used within the IPM framework. Ration significantly influenced several aspects of growth, both at the individual and at the cohort level. Mean final body mass and mean growth rate increased with ration; however, variance in body mass and feed intake also increased significantly over time. Trends in mean body mass and individual body mass variation were captured by both logistic and linear models, suggesting the linear model to be suitable for use in the IPM. The authors also observed that higher rations resulted in a decreasing proportion of individuals reaching the cohort's mean body mass or larger by the end of the experiment. This suggests that, in the present experiment, feeding to satiation did not produce the desired effects of efficient, fast, and uniform growth in juvenile king salmon. Although monitoring individuals through time is challenging in commercial aquaculture settings, recent technological advances combined with an IPM approach could provide new scope for tracking growth performance in experimental and farmed populations. Using the IPM framework might allow the exploration of other size‐dependent processes affecting vital rate functions, such as competition and mortality.
... punctatus × I. furcatus) from egg to stockers in multiple 0.5 and 1.14 m 3 (40 and 300 gal) fiberglass tanks. The hatchery water treatment and reuse system were designed by Freshwater Institute Engineering Services (Shepherdstown, West Virginia, USA) and includes treatment operation equipment found in many coldwater partial reuse systems for Atlantic Salmon Salmo salar and Arctic Char Salvelinus alpinus culture (Summerfelt et al. 2004a(Summerfelt et al. , 2004bVinci et al. 2004;Davidson et al. 2008Davidson et al. , 2016. Components of the reuse treatment system include a rotating microscreen drum filter (Hydrotech) equipped with 60-μ sieve panels, two 7.5hp centrifugal pumps to move water from the lowest grade line (a pump sump, 6.2 m 3 ) to the highest elevation, the top of the Cyclobio fluidized sand biofilter. ...
The ability of a commercial‐scale Cyclobio fluidized sand filter was evaluated for ammonia and nitrite removal by dosing with ammonia chloride, NH 4 Cl, as part of the water treatment unit for the U.S. Department of Agriculture Agricultural Research Service Warmwater Aquaculture Research Unit's (WARU) catfish hatchery in Stoneville, Mississippi, USA. Treatment system water was recirculated through the Cyclobio filter for several months without any feed inputs; thus, our objective was to investigate how quickly a full‐scale Cyclobio fluidized sand filter could be reactivated with NH 4 Cl substrate dosing in preparation for the upcoming spawning season. A second objective of the study was to examine the decline of the filter's nitrification ability when the supplementary NH 4 Cl substrate dosings were removed or limited. The effects of daily and weekly substrate additions were evaluated over a 14‐week winter period, with the system water temperature ranging between 20° and 23°C. Total ammonia nitrogen (TAN) concentration decreased within hours of initial dosing. After approximately a 2‐h lag period, the nitrite–nitrogen concentration peaked and then decreased. The rate of TAN nitrification followed a simple first‐order reaction kinetics and increased over time during the 4 weeks of daily NH 4 Cl substrate dosing. The return to a weekly substrate dosage resulted in a decrease in the kinetic reaction rate, but adequate to maintain the filter during periods of system inactivity. The once‐daily substrate dosage was consumed within hours of the initial dosing and was sufficient for current system loading.
... The latest figures from some producers show fishmeal making up 15 % of Atlantic salmon feed (Mowi, 2021), and though soybean meal content in aquaculture feed is also highly variable, prior research has shown up to 20 % soybean content within feed caused no observable difference in Atlantic salmon health (Olli et al., 1995). Atlantic Salmon are frequently grown to a size of 4-5 kg before harvest (Cohen et al., 2016;Davidson et al., 2016). With a diet comprising 15 % fishmeal (0.66-0.83 kg) and 20 % soybean meal (0.88-1.1 kg), we calculate Atlantic Salmon will be exposed to 1788-3013 anthropogenic particles throughout their commercial lifespan from aquaculture feed, with 706-1660 particles from fishmeal and 1082-1353 particles from soybean meal. ...
Aquaculture is an increasingly important source of nutrition for global food security, which is reliant on animal- and plant-based feeds. Anthropogenic particles, including microplastics and semi-synthetic cellulosic fibres, are prolific marine pollutants that are readily consumed by marine organisms, including small pelagic fish commonly used in fishmeal. Conversely, there is no indication plants can accumulate anthropogenic microparticles. We explore whether aquaculture feed presents a route of contamination for farmed fish. Commercially-sourced aquaculture feedstocks, including fishmeals and soybean meal, were processed (KOH digestion and ZnCl2 density separation) and anthropogenic particles characterised using microscopy and spectroscopic methods. Both fishmeal and soybean meals contained anthropogenic particles, with concentrations ranging 1070-2000 particles kg-1. The prevalence of anthropogenic particles in plant-based feeds indicates that the majority of contamination occurs post-harvest. Based on our findings, farmed Atlantic salmon may be exposed to a minimum of 1788-3013 anthropogenic particles from aquaculture feed across their commercial lifespan.
... EY Global (2021) reported that land-based salmon production volumes doubled from 2016 to 2020, and accelerated growth is forecasted pending completion of numerous construction projects (EY Global, 2021;Martin et al., 2021). Further, the biological and technological feasibility of producing food-size Atlantic salmon in recirculating aquaculture systems (RAS) has been demonstrated via applied research (Crouse et al., 2021;Davidson, May, et al., 2016), and through initial successes of several commercial operations (Cox, 2020;EY Global, 2021). However, barriers to profitable land-based salmon production remain (Engle et al., 2020), including early maturation , solids disposal complexities (Pilone, 2021), and off-flavor accumulation (Azaria & van Rijn, 2018;Lindholm-Lehto & Vielma, 2019), among others (Badiola et al., 2012;Solheim & Trovatn, 2019). ...
Land‐based Atlantic salmon, Salmo salar, grow‐out facilities utilize depuration to remediate off‐flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m3 in an 18 m3 depuration tank. Feed was withheld 1 day before transfer and throughout the 7‐day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2‐methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.
