The use of adaptive feeding systems to deliver feed remotely to Atlantic salmon (Salmo salar) cages has the potential to improve the localised environment through a reduction in particulate waste. This can be achieved through improved growth and lower Feed Conversion Ratio (FCR). The aim of this project was to assess whether adaptive feeding systems confer any environmental benefit at salmon farms through by comparing two fish farm sites, one that uses a Computer Aided System (CAS) adaptive feeding system (AKVAsmart UK limited, Inverness, Scotland) (Portavaide fish farm) and one using hand feeding (Rubha Stillaig). This investigation comprised of 3 elements: 1) a comparative assessment of the quantity and nutrient composition of particulate waste material emanating from the cages; 2) collection of benthic samples plus a video survey along transects at each site including a reference station, with an analysis of differences in benthic fauna, sediment grain size and sediment nutrient composition; and 3) comparison of the distribution of waste under each feeding regime using a GIS-based modelling approach. Particulate waste was collected via sediment traps. Uneaten feed was caught in only 3 out of 184 separate collections and thus no estimate of feed loss for each feeding system could be made. Samples were analyzed for total solids (TS), faecal solids (FS), faecal carbon (FC), faecal nitrogen (FN) content and faecal sedimentation rate (FSR). The highest deposition occurred under the cages and decreased with increased distance from the cage centre. Maximal deposition of TS at Portavadie was higher than at Rubha Stillaig when feed was included, although average TS, FS, Fe and FN per tonne of production did not significantly vary between sites. Carbon sedimentation rate was analyzed using regression analysis and a General Linear Model Factorial ANOVA on faecal waste only and showed no significant differences between sites and, therefore, no difference between feeding methods . There were no differences observed in the diversity and abundance of benthic species under the two feeding systems. By the end of the production period all stations out to 25m from the cage edge were dominated by Capitella capitata at both sites, this species proving a useful indicator of the impact of nutrient deposition. The analysis suggested that Heteromastus filiformis and Corophium sp. provided useful indicators of the onset of nutrient enrichment. Measurement of carbon and nitrogen levels and particle size in sediment showed no difference between sites. Variations between sites in species abundance and diversity and sediment carbon and nitrogen levels reflected the different sediment conditions prevalent at the start of the sampling period. Univariate and multivariate analysis showed there was no difference in species diversity and abundance between the sites as a result of using adaptive feeding systems. Horizontal cage movement, measured at up to 10m, reduced the predicted settlement under the cage by 23% and 11 % for feed and faecal distribution respectively. There was no significant difference in the predicted settlement of waste particulates under adaptive and hand feeding. The GIS model prediction of carbon flux (g C m-2 15-days-1) was validated for faecal settlement using sediment trap data where predictions agreed well with observations from Portavadie fish farm, with an accuracy of ± 53.1 % when all stations were included, improving to ± 27.6% when deposition under the cage was excluded. Overall, the approaches used did not identify specific differences between sites that used adaptive feeding and hand feeding methods. The growth period using the adaptive feeding system was approximately nine weeks shorter than under hand feeding, however, which could be used constructively to increase the fallowing period whilst maintaining current levels of production. This would benefit the localised benthos by increasing the time available for recovery before further production takes place and thus the CAS Adaptive Feeding System could be used as part of a broader sustainable farming strategy for fish culture.

A whole-cell DHA-rich algal product (A-DHA, provided by Evonik Industries) that is rich in DHA (125 mg DHA/g dry matter) is a possible replacement for fish oil in salmonid diets. The nutrient digestibilities of the algal product were measured in rainbow trout in freshwater and in Atlantic salmon in saltwater (32-33 ppm). In experiment 1, rainbow trout (initial weight ~ 300g) were randomly assigned to 12 x 120 L tanks (n = 10 per tank). A reference diet containing 1% Celite as an indigestible marker and three test diets with increasing percentage of A-DHA substitution (6.67%, 13.33% and 20%) were fed. Feces were collected using a settling column and feed and feces analyzed for digestible dry matter (DM), gross energy (GE), ash, crude protein (CP), essential amino acids and total lipid. The digestibility of six long-chain fatty acids including 18:1n-9 (OA), 18:2n-6 (LA), 18:3n-3 (ALA), 20:4n-6 (ARA), 20:5n-3 (EPA) and 22:6n-3 (DHA) was measured. In experiment 2, Atlantic salmon (~170g) were randomly distributed to 12 fiberglass tanks (600L) with 106 fish per tank. The fish were assigned to four diets with the same levels of A-DHA inclusion as for rainbow trout and yttrium oxide (Y2O3) was used as an inert marker. Feces were collected by stripping and the digestibilities of DM, CP and lipid as well as OA, LA, ALA, ARA, EPA and DHA were determined. In experiment 1, the apparent digestibility of dietary DM, GE and lipid in rainbow trout declined significantly with increasing inclusion of A-DHA (P < 0.01). The inclusion of A-DHA had no effect on the digestibility of CP and ash as well as the availability of essential amino acids (P > 0.05). Furthermore, increased inclusion of A-DHA resulted in significantly lower digestibility of ARA, EPA and DHA (P < 0.05). A similar pattern was seen in the digestibility of OA, LA and ALA, although the effect of A-DHA inclusion was not statistically significant. Regression analysis revealed that nutrient contribution from A-DHA had significantly negative linear and quadratic effects on the apparent digestibility of DM, GE, and lipid. The inclusion levels of A-DHA had both significantly negative linear and quadratic effects on digestibility of LA and ALA, whereas only significantly negative linear effect was found on OA. Significantly negative linear and quadratic regressions were observed for the digestibility of ARA, EPA and DHA. The linear regression for CP was significantly negative and the regressions for the individual amino acids were not significant (P > 0.05). In experiment 2, dietary inclusion of A-DHA had a significantly negative effect on lipid digestibility in Atlantic salmon, at all inclusion rates whereas the significant negative effect on digestibilities of DM and CP was only observed in fish fed 20% A-DHA. The digestibilities of OA, LA, ALA and EPA were greater than 91%. In contrast, the apparent digestibilities of ARA and DHA decreased significantly with increasing substitution of A-DHA (P < 0.01). Significantly negative linear and quadratic regressions were found between nutrient contribution from A-DHA to the diets and apparent digestibility of DM, CP and lipid, so were LA, EPA and DHA. However, there were only significant quadratic regressions for OA, ALA and ARA, but not significant linear effects. Subsequently, a twelve-week feeding trial in rainbow trout was conducted to investigate the impact of replacing fish oil with A-DHA in canola-oil-based diets on the growth performance and fatty acid composition and retention. Four experimental diets containing only canola oil (CO; 13.5%), fish oil (FO; 13.5%), canola oil and fish oil (C+F; 7.4% and 6.1%, respectively) or canola oil and A-DHA (C+A; 15.5% and 6%, respectively) were formulated to contain 386.2 g/kg digestible crude protein and 17.58 MJ/kg digestible energy. In addition, the C+A diet was formulated to have the same DHA concentration as in the C+F diet. Each diet was fed to three tanks of rainbow trout (average initial weight of 70g; n = 17/tank) and the fish were fed to apparent satiation 2 times daily. At the end of the growth trial, all fish approximately tripled their weight. No significant differences were noted between the dietary treatments in growth performance as measured by final weight, average weight gain, feed intake, specific growth rate (SGR) and feed conversion ratio (FCR). Although FO and C+A fed fish tended to accumulate more lipids, final whole body lipid content did not differ significantly between dietary treatments (P = 0.11). The concentrations of EPA, DHA as well as total n-3 fatty acid were significantly higher in fish fed the FO diet than fish fed the other 3 diets. The C+A fed fish had lower EPA and higher DHA concentrations compared with the CO and C+F fed fish; however, the differences were not significant. Apparent retention of total lipid in the trout was not significantly influenced by treatments (P > 0.05). Similarly, dietary treatments had no significant effect on the apparent retention of total saturated fatty acids, total mono-unsaturated fatty acids, n-3 polyunsaturated fatty acids and n-6 polyunsaturated fatty acids. The retention of 18:4n-3 (SDA) was significantly higher (> 100%) in fish fed CO and C+A compared with fish fed FO and C+F (< 51%), indicating greater bioconversion of ALA to SDA in the CO and C+A fed fish than in FO and C+F fed fish. The retention of EPA in the CO and C+A fed fish was over 100%, suggesting a net synthesis of EPA in these treatment groups. In contrast, the EPA retention in the FO and C+F fed fish was 55 and 21%, respectively, which showed a tendency to be significantly lower than that in the other two groups (P = 0.09). The CO fed fish had significantly higher DHA retention than fish fed the other 3 diets. The DHA retention in the FO fed fish (112%) was numerically but not significantly higher than in the C+F (66%) and C+A fed fish (73%). Thus, feeding the C+A to rainbow trout resulted in DHA retention equal to feeding the C+F.

I Vänern, Sverige, fångades årligen ca 75 ton lax och öring av yrkesfisket, sportfisket och fritidsfisket under 1990-talet och början av 2000-talet. Fångsterna av lax och öring verkar ha sjunkit under de senaste åren men det råder stor osäkerhet över fångstuppskattningar. För en ökad förståelse över smolts mortalitet släpps varje år ett visst antal Carlin-märkta laxar och öringar ut i Vänern och Klarälven. Syftet med studien var att sammanställa och analysera databasen för Carlin-märkt lax och öring i Vänern under åren 1965 till 2005. Målet var att åskådliggöra långsiktiga tendenser över återfångster av Carlin-märkt lax och öring i både Vänern och Klarälven samt bedöma om återfångster varierar beroende på utsättningsplats (Vänern eller Klarälven). Microsoft Excel användes för att sammanställa och analysera återfångad och inrapporterad lax och öring från 1965 till 2005. För att bedöma trender för återfångster av de fyra stammarna, Gullspångs- och Klarälvs-, lax och öring, användes linjär regression. Totalt 299 165 Carlin-märkta fiskar fördelade över 388 utsättningsgrupper har släppts ut i Vänern med tillflöden under 40 års tid. Sammanlagt återfångades 14 504 fiskar, vilket motsvarar knappt 5 % av antalet Carlin-märkta och utsläppta fiskar. Återfångsterna har varierat genom åren (&lt;1 % - &gt;20 %), högst var återfångsterna under 1970-och 1980-talet, sedan 1990-talet har de minskat betydligt. Dessa tendenser är liknande för alla fyra stammar. De flesta återfångsterna sker i Vänern. Fisk utsläppt i Vänern återfångas som regel i något högre grad i Vänern än fisk utsläppt i Klarälven. Slutligen framkom att ingen lax eller öring utsläppt i Vänern återfångades i Klarälven. / In Lake Vänern, Sweden, commercial, sport, and subsistence fisheries in the 1990s and the beginning of 2000 caught about 75 tons of salmon and trout. Catches of salmon and trout appeared to have declined in recent years, although there is much uncertainty in catch estimates. In order to better understand smolt-adult mortality, a number of Carlin-tagged salmon and trout are released in Vänern and Klarälven each year. The aim of the study was to assemble and analyze the Carlin-tag database for salmon and trout in Vänern during the years 1965 to 2005. My objectives were to identify long-term trends in tag returns rates in both Vänern and Klarälven, and to assess whether return rates varied by release location (Vänern or Klarälven). Microsoft Excel was used to compile and analyze reported recoveries of Carlin-tagged salmon and trout from 1965 to 2005. Linear regression was used to assess trends in return rates of four stocks, Gullspångsälven and Klarälven salmon and trout. Total 299 165 tagged fish in 388 release groups have been released in Vänern over the 40-year period. Total recaptures were 14 504, which equates to just under 5 % of the number of Carlin-tagged and released fish. Recapture rates have varied throughout the years (&lt;1 % - &gt;20 %), the highest return rates were in the 1970s – 1980s, but they have decreased significantly since the 1990s. These trends are similar for all four stocks. Most of the recaptures occur in the lake, return rates of fish released in the lake are most often caught in the lake than are fish released in Klarälven. Finally, revealed that no salmon or trout that were released in the lake were recaptured in the Klarälven.

This thesis relates fluvial morphology to those hydraulic conditions identified as being ideal for the rearing of juvenile Atlantic salmon. The suitability of flow depths and velocities were obtained from published habitat preference curves in order to compute the percent area (percent usable area - PUA) and average width (average usable width - AUW) of reaches providing ideal rearing habitat for juvenile Atlantic salmon at 2 typical summer discharge levels, in the Ste. Marguerite River. / By dividing reaches into smaller, morphologic unit's, in order to make the conditions more uniform, it was noticed that the wetted width and the amplitude of the vertical oscillation of riffles and pools (riffle-pool amplitude) provided the strongest hydraulic and morphologic relationships with the amount of usable habitat at the morphologic unit scale. Two regression models were produced to estimate the AUW of morphologic as a function of hydraulics and morphology, respectively. / The historic flood in July 1996 also provided an opportunity to examine some of the impacts of a large magnitude flood on channel morphology: localized bed and bank erosion, the destruction of riparian vegetation, the enhancement and destruction of individual bars, and localized changes in the hydraulic and morphologic character (induced by large sediment inputs).

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 6 uppsatser.

Research has been actively looking for alternative feed ingredients to reduce the reliance of the aquafeed industry on marine ingredients, namely fish meal (FM) and fish oil (FO). In this context, insects, in particular housefly (Musca domestica) and black soldier fly (BSF, Hermetia illucens) larvae, have been identified as promising candidates. Although a global insect farming industry is emerging, it is for now constrained by regulatory and technical bottlenecks that raise the question ‘where and how insect-based products could be integrated into aquaculture’. The literature indicated a high interspecies variability of the results when replacing FM with insect meals in fish diets and previous work failed to consider the existing challenges related to the insect production to demonstrate commercial relevance and applicability. In this thesis, maggot meals (MM) and frass (insect digestate) were assessed as strategic feed ingredients for two commercially important farmed species: Atlantic salmon, (Salmo salar) and Nile tilapia (Oreochromis niloticus), in their relevant contexts. Case studies showed that both housefly and BSF MM are high quality feed ingredients and suitable alternative to FM. Specifically, dietary inclusions of up to 200 g/kg of crude or defatted housefly larvae meal did not compromised the feed digestibility and utilisation and the growth performance and body composition of salmon parr (freshwater stage), compared to a FM-based control diet. Hormone (17α-methyltestosterone) treated diets containing between 250 and 1000 g/kg BSF or housefly meal were found as effective as a commonly used pure hormone-treated FM in sex-reversal process leading to 99.8 to 100% males, high survival and evenness of the fish produced. In a commercial diet for advanced nursing of Nile tilapia fingerlings, up to 80 g/kg BSF meal was included without impairing the fish performance and body composition; dietary inclusion was limited by the lipid content of the crude MM. Finally, BSF frass derived from brewery spent grains or processed food wastes were found more effective when used as soil bio-fertilisers with minimum application rate of 10.0 tonnes/ha or 5.0 tonnes/ha, respectively (for a spring onion culture), rather than supplemental feeds for tilapia farmed in semi-intensive conditions (fertilised pond). The study also indicated that site-specific conditions should be accounted to support appropriate and sustainable use of insect-based products but in any case, juvenile fish should be strategically targeted given their requirements. It is expected that this approach, could support the sustainable intensification of aquaculture and contribute more broadly to food security whilst contributing to the development of a circular economy.

Environmental pollution by pharmaceuticals is an issue of concern that is currently attracting attention around the world. Although environmental effects of pharmaceutical contaminants are not yet well documented, studies have shown that these substances may have the potential to disrupt the biotic component of an ecosystem. Particularly worrisome contaminants are the neuroactive pharmaceuticals which have the potentiality to induce behavioral modifications in non-target species. In the present study, I examined the effects of a benzodiazepine anxiolytic pharmaceutical (oxazepam) on the behavior of Atlantic salmon (Salmo salar) juveniles (fry). The hypothesis of this study was that oxazepam reduces the anxiety-like behavior of the Atlantic salmon juveniles. To test the hypothesis and assess the impact of oxazepam exposure on Atlantic salmons fry behavior, two different concentrations of this drug; a low-level (1.9 ug L-1) and a high-level concentration (1000 ug L-1) were used. Exposures lasted for 48 hours and afterwards, the fish were recorded to evaluate their behavioral responses. The results of this study reveal that oxazepam in a high concentration (1000 ug L-1 ) alters specific behavioral endpoints related to the fitness (feeding/predator avoidance) of Atlantic salmons fry. Individuals exposed to the high oxazepam concentration exhibited significant lower average speed and acceleration as well as they traveled a shorter mean distance compared to the unexposed (control) individuals. These findings confirm the hypothesis and show that psychotropic pharmaceutical contaminants modify animal behaviors, which can ultimately lead to ecological consequences. However, the concentration that generated behavioral effects in this study was three magnitudes higher than concentrations measured in the environment and thus, should not be viewed representative for oxazepam contaminated ecosystems.

No description available.

Marine omega-3s, EPA and DHA, have been strongly evidenced to decrease the risk of cardiovascular disease, the leading cause of death in the United States. One of the richest sources of EPA and DHA in the U.S. diet is farmed Atlantic salmon, which has shown a steady consumption growth in the past decade. The U.S. shows the most production potential for salmon produced with an emerging production method, recirculating aquaculture systems (RAS), which directly addresses the environmental challenges associated with the traditional farming method, open-net pens. Because of the higher costs associated with RAS, the salmon it produces requires a price premium, and little is known about whether U.S. consumers are willing to pay such a premium. We conduct a hypothetical choice experiment across all major regional markets of the U.S. (n = 2857) to estimate consumers' willingness-to-pay for RAS and other attributes valued by producers and consumers. Our results show that U.S. consumers are willing to pay a premium for RAS, but only after prioritizing freshness (fewer days since harvest) and U.S. production, all of which were significant to the p < .001 level. Higher omega-3 content also justified a significant premium, but byproduct recycling and stocking density did not have any real influence on purchases. We express these willingness-to-pay (WTP) estimates as percentages of a reference product priced with model estimates. These adjusted retail premiums should be paired with RAS salmon production costs to understand the economic viability of RAS and illuminate the path to EPA and DHA nutrient security in the U.S. / Master of Science / Two micronutrients found in cold-water fish, EPA and DHA, have been strongly evidenced to decrease the risk of cardiovascular disease, the leading cause of death in the United States. One of the richest sources of EPA and DHA in the U.S. diet is farmed Atlantic salmon, which has shown a steady consumption growth in the past decade. The U.S. shows the most production potential for salmon produced with an emerging production method, recirculating aquaculture systems (RAS), which directly addresses the environmental challenges associated with the traditional farming method, open-net pens. Because of the higher costs associated with RAS, the salmon it produces requires a price premium, and little is known about whether U.S. consumers are willing to pay such a premium. We conducted an experiment with U.S. consumers (n = 2857) to estimate willingness-to-pay for RAS and other attributes valued by producers and consumers. Our results show that U.S. consumers are willing to pay a premium for RAS, but only after prioritizing freshness (fewer days since harvest) and U.S. production. Higher omega-3 content also justified a significant premium, but byproduct recycling and stocking density did not have any real influence on purchase

Caligid copepods, also called sea lice, are ectoparasites of marine fish, with Lepeophtheirus salmonis (Krøyer, 1837) emerging as a problem for mariculture of Atlantic salmon (Salmo salar Linnaeus, 1758) in the northern hemisphere. Annual costs of sea lice to global salmon farming was estimated to be in excess of €300 million in 2006, with the majority of this accounted for through expenses accrued from chemical treatments. Only a limited range of anti-sea louse drugs are available and licensed for the treatment of fish, and the continued use of only a few compounds creates a situation potentially favouring the development of drug resistance. Emamectin benzoate (EMB) is currently used as a salmon delousing agent, being employed as a 0.2 % in-feed pre-mix (SLICE®). Atlantic salmon farmers have reported increased incidence of reduced L. salmonis sensitivity to SLICE®, which has highlighted the requirement for further research into the molecular mechanisms controlling salmon louse resistance to EMB. Genomic and transcriptomic research concerning L. salmonis drug resistance mechanisms has not often been reported, with previous transcriptomic studies using candidate gene approaches and genetic studies focussing on population genetics. Drug resistance in ecdysozoan invertebrates is associated with a variety of molecular mechanisms including target site mutations and changes in the expression of components in drug detoxification pathways. The research reported in this thesis was aimed at the exploration of mechanisms employed by L. salmonis to reduce the toxicity of EMB exposure, following a transcriptomic approach that utilised custom oligonucleotide (oligo) microarrays and a genetic approach that utilised Restriction-site associated DNA sequencing (RAD-seq) to identify Single Nucleotide Polymorphism (SNP) markers. An EMB-resistant (PT) and drug-susceptible (S) L. salmonis laboratory-maintained strain were to be used as a model for this research, as these two strains differ in EMB susceptibility (~ 7-fold) and show stable susceptibility profiles through multiple generations, suggesting that this drug resistance phenotype may be a heritable trait. Sequence resources available for salmon lice are limited as an annotated L. salmonis genome is currently under construction. Therefore, a significant amount of this study involved creating new resources to facilitate the analysis of EMB susceptibility. Suppression subtractive hybridisation (SSH) was used to enrich for transcripts that were differentially expressed between strains PT and S, which provided sufficient target sequence for the development of 15K oligo microarrays when combined with sequences assembled from existing L. salmonis ESTs. Additionally, transcripts were generated through sequencing a pooled sample representing key developmental stages of the L. salmonis life cycle, which were later used in the construction of a 44K oligo microarray. The toxicity of EMB and other avermectins (AVMs) against ecdysozoan invertebrates is reported to be based mainly on their interaction with ligand-gated ion channels (LGIC), specifically glutamate-gated chloride channels (GluCl). However, -aminobutyric acid (GABA)-gated chloride channels (GABA-Cls) are also believed to be targeted by AVMs and neuronal acetylcholine receptors (nAChRs) can be allosterically modulated by the AVM compound ivermectin. Transcriptional responses in PT and S salmon lice were investigated using custom 15K L. salmonis oligo microarrays. In the absence of EMB exposure, 359 targets differed in transcript abundance between the two strains. GABA-Cl and nAChR subunits showed significantly lower transcript levels in PT compared to S lice, which was estimated at ~1.4-fold for GABA-Cl and ~2.8-fold for nAChR using RT-qPCR, suggesting their involvement in AVM toxicity in caligids. Although, salmon lice from the PT strain showed few transcriptional responses following acute exposure (1 or 3 h) to 200 µg L-1 of EMB, a drug concentration tolerated by PT lice, but toxic for S lice. RAD-seq analysis of both genders from L. salmonis strains S and PT identified 15 RAD-markers that show complete association with salmon louse strain, although these preliminary results will need further analysis to confirm marker association with reduced EMB susceptibility. Additionally, RAD marker Lsa101901 showed complete association with sex for all individuals analysed, being heterozygous in females and homozygous in males. Using an allele-specific PCR assay, this SNP association pattern was further confirmed for three unrelated salmon louse strains. Marker Lsa101901 was located in the coding region of the prohibitin-2 gene, which showed a sex-dependent differential expression, with mRNA levels determined by RT-qPCR about 1.8-fold higher in adult female than adult male salmon lice. In conclusion, the identification of decreased transcript abundances for LGIC subunits in EMB-resistant salmon lice, and polymorphic SNP markers showing complete association with L. salmonis strains S or PT, provides suitable candidates for further investigation into their association with reduced EMB susceptibility. Further analysis will also be required to confirm whether EMB-induced mechanisms are not associated with reduced EMB susceptibility in L. salmonis. Additionally, the identification of sex-linked SNP Lsa101901 suggests that sex determination in the salmon louse is genetic and follows a female heterozygous system, with marker Lsa101901 providing a tool to determine the genetic sex of salmon lice. Improved knowledge of L. salmonis biology and the mechanisms potentially involved in EMB resistance, obtained during this study, may provide molecular markers that contribute to successful monitoring and management of this commercially important parasite of Atlantic salmon.