Salmon Fillets Research Articles

Effect of pancreas disease (PD) on quality attributes of raw and smoked fillets of Atlantic salmon ( Salmo salar L.)

The impact of pancreas disease (PD) on fillet quality of raw and cold-smoked Atlantic salmon was investigated. Commercially reared fish were sorted into six groups: (1) Control (healthy fish), (2) SAV (infection with salmonid alphavirus, without PD outbreak), (3) PD0 (PD diagnosis at slaughter), (4) PD6 and (5) PD12 (diagnosed 5–7 and 11–12 months before slaughter, respectively) and (6) PDchronic (repeated PD outbreaks). The condition factor (CF) and fillet protein content were significantly higher for the control group (1.13 and 22.1%, respectively). The CF was lowest for PDchronic (0.92), whereas the fillet protein content was lowest in PD0 (20.2%). Fillet fat content did not vary significantly between the groups, but the muscle pH was 0.2 units higher in PD12 as compared to Control. Astaxanthin (Ax) and idoxanthin (Ix) content were significantly lowest for PD0. Ax recovered six months after the outbreak, but the Ix content remained lower in the PD affected salmon. The Ax level after smoking was similar for all groups, but Ix showed a similar pattern to that of raw fillets. Results of the colorimetric analyses ( L*, a*, b*) indicated darkest colour for the control group and palest colour for PD0, whereas PDchronic showed highest differences between raw and smoked fillets. Firmness of raw fillets was lowest in PDchronic, but after smoking a significantly higher firmness was found in PDchronic, PD0 and PD6 (16.7–19.7 N) compared with that of Control and PD12 (14.1 N). Changes in fillet quality in the order of their appearance were decreased CF, depleted muscle glycogen, increased drip loss of raw muscle, paler colour, depleted protein and finally harder texture in smoked salmon. It is concluded that the fillet quality deteriorated after a PD outbreak, but the quality may to a large extent recover.

Classification of fresh Atlantic salmon (Salmo salar L.) fillets stored under different atmospheres by hyperspectral imaging

Hyperspectral imaging (HSI) was used to investigate spectroscopic changes in fresh salmon stored under different atmospheres (air, 60% CO2/40% N2 and 90% vacuum) and to determine whether HSI can classify fillets by the type of packaging. Hyperspectral images of samples kept at 4°C were acquired and bacterial growth and lipid oxidation were measured. Principal component analysis was applied to study spectral development of samples during storage and K nearest-neighbour classifier was used for the classification of fillets by packaging type. Partial least squares regression was run to reduce the number of wavelengths included in the classification model. The results demonstrated that spectral variations could be observed in the different packaging atmospheres primarily at the wavelengths 606 and 636nm. Using HSI, successful classification of fillets according to the packaging used (>88%) was achieved and this was largely dependent on spectral characteristics at the wavelengths 606 and 636nm, possibly due to the different oxidation states of the haem proteins in the muscles.

Relevance of calpain and calpastatin activity for texture in super-chilled and ice-stored Atlantic salmon (Salmo salar L.) fillets

The aim of the present experiment was to measure the protease activities in ice-stored and super-chilled Atlantic salmon (Salmo salar) fillets, and the effect on texture. Pre-rigour fillets of Atlantic salmon were either super-chilled to a core temperature of −1.5°C or directly chilled on ice prior to 144h of ice storage. A significantly higher calpain activity was detected in the super-chilled fillets at 6h post-treatment compared to the ice-stored fillets and followed by a significant decrease below its initial level, while the calpastatin activity was significantly lower for the super-chilled fillets at all time points. The cathepsin B+L and B activities increased significantly with time post-treatment; however, no significant differences were observed at any time points between the two treatments. For the ice stored fillets, the cathepsin L activity decreased significantly from 6 to 24h post-treatment and thereafter increased significantly to 144h post-treatment. There was also a significantly lower cathepsin L activity in the super-chilled fillets at 0h post-treatment. No significant difference in breaking force was detected; however, a significant difference in maximum compression (Fmax) was detected at 24h post-treatment with lower Fmax in the super-chilled fillets. This experiment showed that super-chilling had a significant effect on the protease activities and the ATP degradation in salmon fillets. The observed difference in Fmax may be a result of these observed differences, and may indicate a softening of the super-chilled salmon muscle at 24h post-treatment.

Microbial communities on Australian modified atmosphere packaged Atlantic salmon

The role of specific spoilage organisms (SSO) in products such as Atlantic salmon has been well documented. However, little is known about what other micro-organisms are present and these organisms may indirectly influence spoilage by their interactions with the SS0. We used a combination of culture-based and DNA-based methods to explore the microbial communities found on Atlantic salmon fillets packed in a modified atmosphere of carbon dioxide and nitrogen. After 15 days the communities were dominated by Shewanella spp. or Carnobacterium spp. and a variety of other genera were present in smaller numbers. Variability in the microbial community composition in packages processed on the same day was also observed. This was mostly due to differences in the presence of minor members of the community including species from genera such as Iodobacter, Serratia, Morganella and Yersinia. The combination of culture-based and culture-independent methods provided greater insight into the development of microbial communities on Atlantic salmon than would have been possible using only one method. This work highlights the potential importance of lactic acid bacteria (LAB) in fresh Atlantic salmon stored under modified atmosphere conditions.

Evaluation of the Effectiveness of a New Antimicrobial Active Packaging for Fresh Atlantic Salmon (Salmo Salar L.) Shelf Life

Nowadays, consumers demand for fresh, high‐quality seafood products continues to climb, especially in affluent, developed nations. At the same time, there is increasing attention regarding improved utilization of seafood for human consumption; Atlantic salmon is the main species in Chile aquaculture, and most of the salmon are exported as fresh fish to USA.It is well documented that low storage temperature inhibit bacterial growth and biochemical degradation, thus facilitating prolonged shelf life. Partly freezing the outer fillet layer from −0.5°C to −2.0°C (superchilling) has proven to be more efficient in inhibiting biochemical changes and bacterial spoilage compared with traditional chilling. Nevertheless, antimicrobial active packaging offers the possibility to increase product shelf life through the reduction of the microbiological damage of the product during its transportation, and thus increasing consumer safety and health. The main objective of this study was to compare the effects of an active antimicrobial packaging on microbiological growth, sensory attributes and instrumental quality measurements of raw Atlantic salmon (Salmo salar) fillets. Flexible plastic films containing Thymol as antimicrobial agent were used for salmon packaging. Salmon were stored at 2°C, 4°C and 8°C. Analyses of aerobic mesophilic bacteria and psicrophilic bacteria count were carried out at 1, 3, 8, 11, 15 and 18 days. L*a*b* colour evolution, overall sensorial properties and chemical evolution were studied. Application of active antimicrobial packaging for fillet salmon reduced the microbial count for least 18 days at 2°C. No modification of the sensorial properties was detected by the sensorial panel, indicating that the antimicrobial compound used in the present study, thymol, is compatible with salmon packaging. Copyright © 2011 John Wiley & Sons, Ltd.

Chronic Consumption of Farmed Salmon Containing Persistent Organic Pollutants Causes Insulin Resistance and Obesity in Mice

BackgroundDietary interventions are critical in the prevention of metabolic diseases. Yet, the effects of fatty fish consumption on type 2 diabetes remain unclear. The aim of this study was to investigate whether a diet containing farmed salmon prevents or contributes to insulin resistance in mice.Methodology/Principal FindingsAdult male C57BL/6J mice were fed control diet (C), a very high-fat diet without or with farmed Atlantic salmon fillet (VHF and VHF/S, respectively), and Western diet without or with farmed Atlantic salmon fillet (WD and WD/S, respectively). Other mice were fed VHF containing farmed salmon fillet with reduced concentrations of persistent organic pollutants (VHF/S-POPs). We assessed body weight gain, fat mass, insulin sensitivity, glucose tolerance, ex vivo muscle glucose uptake, performed histology and immunohistochemistry analysis, and investigated gene and protein expression. In comparison with animals fed VHF and WD, consumption of both VHF/S and WD/S exaggerated insulin resistance, visceral obesity, and glucose intolerance. In addition, the ability of insulin to stimulate Akt phosphorylation and muscle glucose uptake was impaired in mice fed farmed salmon. Relative to VHF/S-fed mice, animals fed VHF/S-POPs had less body burdens of POPs, accumulated less visceral fat, and had reduced mRNA levels of TNFα as well as macrophage infiltration in adipose tissue. VHF/S-POPs-fed mice further exhibited better insulin sensitivity and glucose tolerance than mice fed VHF/S.Conclusions/SignificanceOur data indicate that intake of farmed salmon fillet contributes to several metabolic disorders linked to type 2 diabetes and obesity, and suggest a role of POPs in these deleterious effects. Overall, these findings may participate to improve nutritional strategies for the prevention and therapy of insulin resistance.

The localisation of pectin in Sphagnum moss leaves and its role in preservation

Abstract The localisation of pectin in Sphagnum moss leaves and its role in preservation has been investigated. Light microscopy using ruthenium red to detect pectin in whole and sectioned Sphagnum papillosum leaves revealed it is abundant in hyaline cell walls, fibrils, papillae, chlorophyllous cell walls and thickenings around hyaline cell pores. Transmission electron microscopy of ultrathin cell walls labelled with poly- l -lysine colloidal gold revealed pectin was distributed throughout the cell wall. The preservative/microbiocidal properties of these pectins are explained by the acid-dissociation properties of galacturonic acid carboxyls and their incorporation in the unique cell arrangement of the Sphagnum leaf. Liquid from a salmon fillet absorbed into S. papillosum leaves and incubated at room temperature for 22 h had a pH around 4.85, was dominated by Lactobacillus sp. and smelled fresh compared to experimental controls. Chlorite-treated Sphagnum leaves could have a potential as a food tray pad that absorbs liquid and prevents the growth of spoilage bacteria inside it.

Dielectric properties of sea cucumbers (Stichopus japonicus) and model foods at 915 MHz

Short-time microwave (MW) sterilization is a feasible technology to produce high-quality shelf-stable sea cucumbers (SCs) (Stichopus japonicus). Selection of a model food matching the sea cucumbers in dielectric properties (DPs) is one of the most important steps for developing the MW processing. The test results revealed that rehydrated sea cucumber has much lower relative dielectric loss factor (9.73–5.62) than muscle foods, including salmon fillets and sliced beef, which were reported in the literature. The whey protein gel formulations that had been developed in our laboratory as a tool in heating pattern studies for those products are, therefore, not appropriate for sea cucumber. Adding 1.0% gellan powder sharply reduced the amount of whey protein concentrates needed to form firm gels and significantly lowered the dielectric loss factor. The dielectric properties of the sea cucumbers and model food samples with different formulations were measured using a custom-built temperature controlled test cell and an Agilent 4291B impedance analyzer in the temperature range 20–120°C. Based on comparison of the measured dielectric properties and the calculated microwave power penetration depths among the sea cucumbers and model foods, appropriate formulation with whey protein concentration 5%, whey protein isolation 3%, gellan gum 1%, d-ribose 0.5% and water 90.5% was chosen as the model food for the sea cucumbers for the purpose of MW processing development.

Investigations on the metabolism and potentially adverse effects of ethoxyquin dimer, a major metabolite of the synthetic antioxidant ethoxyquin in salmon muscle.

The feed additive ethoxyquin (EQ) is a commonly used synthetic antioxidant preservative in animal feeds. In farmed Atlantic salmon fillets, EQ residues are present, both as the parent compound and as EQ derivatives. One of the main EQ derivates in fish muscle is an ethoxyquin dimer (EQDM), and the potential toxicity of this metabolite is not known. The aim of this study was to evaluate the metabolism and potentially toxicological effects of EQDM. A 90-day subchronic exposure study with repeated dietary exposure to EQDM at 12.5 mg/kg of body weight per day was performed with male F344 rats. Hepatic Cyp1a1 mRNA was significantly reduced to <3% of the control in rats fed EQDM, and hepatic Cyp2b1 mRNA was increased to 192%. EQDM increased Gstpi1 mRNA expression to 144% that of the control, but the activity level of this phase II enzyme was reduced. Biomarkers of liver and kidney function did indicate adverse effects of EQDM when F344 rats were fed 12.5 mg/kg of body weight per day. The present study revealed that EQDM produces responses that are comparable to those produced by the parent compound (EQ) in terms of activating the same enzyme systems.

Acute satiety response of mammalian, avian and fish proteins in dogs

Fish proteins have been reported to be more satiating than meat proteins. The objective was to determine the effect of different animal protein pre-meals on satiety. A total of ten intact female hounds were fed pork loin, beef loin, chicken breast, salmon fillet or pollock fillet. Each pre-meal was fed to contain 100g protein. Blood was collected at 0, 5, 15, 30, 60, 90 and 120min postprandially and analysed for glucose, insulin, total ghrelin, active glucagon-like peptide-1 (GLP-1) and plasma amino acids (AA). Dogs were fed 2× metabolisable energy, 3h following the pre-meal, and intake was determined 30, 60, 180 and 1440min after food presentation. Glucose decreased over time (P<0·001), but was lowest (P=0·01) when dogs consumed pollock or chicken. Insulin increased (P<0·0001) over time, and was greater (P=0·09) when dogs consumed salmon. GLP-1 increased (P<0·001) over time, and was greatest (P=0·04) when dogs consumed beef. Ghrelin decreased (P<0·0001) over time for all pre-meals. The tryptophan:large neutral AA ratio tended to be greater (P=0·08) when dogs consumed pork, salmon and pollock. Different protein sources may influence blood markers in dogs, but it does not appear that fish substrates have different satiating abilities than mammalian or avian sources.

Effects of Storage Atmosphere and Heme State on the Color and Visible Reflectance Spectra of Salmon (Salmo salar) Fillets

It has previously been observed that the color of mackerel muscle is dependent on the status of heme as myoglobin and hemoglobin and hence the storage atmosphere. This study gives strong indications of this being the case also in salmon. Three different storage conditions were used to promote the oxidized, reduced, and carbon monoxide (CO) bound forms of heme in salmon and mackerel fillets. Color determination (instrumental color analysis, imaging, and sensory evaluation) and spectroscopic measurements were performed to study how spectral changes corresponded to color variations. Storage in CO significantly increased the redness in mackerel. This was also seen in salmon to such a degree that it was visible over normal levels of salmon carotenoids. Air storage increased the yellowness and reduced the redness in mackerel, but this effect was partly concealed in salmon by the astaxanthin absorption. The spectral differences due to storage condition could be ascribed to the spectral features characterizing heme of different oxidation states and bound to different ligands. The status of heme should therefore always be considered when experiments related to salmon color are performed. The findings could help in the understanding, control, and prediction of color loss in salmon during processing, storage, and transport.

Residues of PBDEs in northeastern Pacific marine fish: Evidence for spatial and temporal trends

In the flesh (skinless fillet) of chinook, chum, coho, pink, and sockeye salmon (Oncorhynchus tshawytscha, O. keta, O. kisutch, O. gorbuscha, and O. nerka, respectively), sablefish (Anoplopoma fimbria) and walleye pollock (Theragra chalcogramma) from several sites in the northeast Pacific sampled between 2002 and 2008, tetra- and pentabrominated diphenyl ethers (BDEs) (BDE 47, 49, 99, and 100) dominated the congener distribution. Chinook and sablefish contained the highest concentrations, followed by sockeye, coho, and pink salmon, and pollock. In sockeye from the Bering Sea - Aleutians and from the Gulf of Alaska, total tri- to hepta-BDE concentrations fell significantly between 2002 and 2005; in sablefish from Gulf of Alaska, there was a steady but statistically nonsignificant decline in BDE concentrations between 2002 and 2008. Relative proportions of the main BDE congeners did not change appreciably over time, within species or location. All species except sockeye salmon showed a clear southeastward increase in BDE concentrations, implying an increasing gradient in general ecosystem contamination. In chinook, coho, and sablefish, especially, the southeastward trend in increasing total concentrations was associated with increasing proportions of BDEs 47 and 100. Chinook returning to western North American natal streams appeared to accumulate most of their PBDE burden towards the end of their migration. Fish from more northern sampling sites often had higher proportions of more highly brominated congeners than those from more southern sites, perhaps reflecting contamination from Asian sources where higher-brominated commercial PBDE formulations are used. In sablefish and pollock, the relative proportions of BDEs 99 and 47 varied inversely in almost a 1:1 ratio, implying debromination of BDE 99 to 47.

Evaluating instrumental colour and texture of thermally treated New Zealand King Salmon (Oncorhynchus tshawytscha) and their relation to sensory properties

Farmed New Zealand King Salmon (Oncorhynchus tshawytscha) was prepared according to common consumer techniques, namely poached, steamed, microwaved, pan fried (no oil), oven baked (no oil) and deep fried (in sunflower oil). Colour and texture were measured instrumentally and a sensory evaluation comprising of a generic QDA was conducted for the intensity and overall liking of the properties of colour, texture, flavour and aroma.During the thermal treatment (cooking), the outer colour of the King Salmon fillets became lighter, more red and yellow. Thermal treatment increased the texture firmness, chewiness and springiness of King Salmon as measured by texture analyser. Overall, the sensory panel preferred the oven baked King Salmon but least liked the poached and microwaved King Salmon. The instrumental texture measurements of the cooked King Salmon were closely linked with the texture ratings from the sensory panel. These experiments provide useful data for determining the optimal preparation techniques that in turn can facilitate the farming of NZ King Salmon to directly benefit the consumer.

Evaluation and suitability of biomaterials for modified atmosphere packaging of fresh salmon fillets

AbstractAn evaluation of the suitability of commercially available biopolymers on the shelf‐life of fresh salmon fillet was done. The comparison included two different types of biomaterials, poly lactic acid (PLA)‐based and starch‐based materials, and two traditional materials, amorphous polyethylene terephthalate/polyethylene (APET/PE) and high‐density polyethylene (HDPE). Fresh salmon fillets were stored at 4°C in modified atmosphere (60% CO2 and 40% N2) for 5, 7, 9 and 14 days. The biomaterials have been briefly evaluated with respect to composition and mechanical properties. The effect of different packaging materials on bacterial growth, off‐odour, pH and colour was investigated.The traditional materials (APET/PE and HDPE trays) offered the best protection regarding the bacterial growth. A relatively high level (log 6 CFU/g) of total viable counts was detected after 9 days and 14 days for fillets stored in biomaterials and traditional materials, respectively. The level of lactic acid bacteria and H2S producing bacteria followed almost the same pattern.Storage in traditional materials resulted in higher intensity of freshness (fresh odour) compared with the samples stored in biomaterials; after 14 days, the salmon stored in starch‐based pouches was regarded as having lower intensity of freshness compared with APET/PE trays and PLA‐based pouches. The opposite result was obtained regarding the colour of the salmon, where the biomaterials resulted in higher intensity of fresh colour compared with the traditional materials although the surface of the salmon at the end of the experiment was dry and unpleasant. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Quantification of Gaping, Bruising, and Blood Spots in Salmon Fillets Using Image Analysis

An image analysis method was developed to quantify the gaping, bruising, and blood spots of red salmon (Oncorhynchus nerka) fillets. Images of 15 fillets with various levels of gaping were taken either with a dSLR camera, or with a video camera. Also, the same fillets were recorded using the same camera both under regular illumination, and under polarized illumination. In either case, light at an angle was used to highlight the gapes in the flesh. An image analysis method was developed that can adaptively apply an L*threshold value to the image depending on the average color of the fillet, and quantify the resulting percent of the fillet area that has an L* value less than or equal to L*threshold. Polarized lighting changed the color by eliminating artifacts resulting from reflections. It is recommended to use polarized light for this purpose. Both cameras could be used adequately to quantify defects. The proper setting of the L*threshold value depended on the camera and on the polarized light. No correlation could be found between the average L* value of the fillets and the L*threshold value. It was possible to quantify the gaping, bruising, and blood spots on the salmon fillets using this method, which can be the first step toward the automation of this operation. Gaping, bruising, and blood spots can be recognized and quantified by analyzing images of salmon fillets. Polarized light is recommended to eliminate color artifacts caused by reflected light. This can be used to automate the detection of these defects.

Visible/Near‐Infrared Spectroscopy Detects Autolytic Changes during Storage of Atlantic Salmon (Salmo salar L.)

Visible (VIS)/near-infrared (NIR) spectroscopy was used to investigate spectroscopic changes occurring during storage of Atlantic salmon fillets with and without bacterial growth. A storage experiment was conducted for 11 d postmortem. Bacterial growth was inhibited by soaking a group of salmon fillets in 3 mM NaN3 prior to storage, while a control group retained its normal bacterial growth. Spectra were obtained by directly applying the spectroscopic probe onto the loin part of each fillet stored under conditions accelerating degradation. Principal component analysis (PCA) was used to monitor and compare spectroscopic development of the 2 groups and the results showed that VIS/NIR spectral changes occurred in the control as well as the treated group of samples within a single day after filleting. After 2 d of storage, stored samples were distinguishable from those fresh in both groups and it was only after the microbial spoilage became pronounced (8 to 9 log colony forming unit [CFU]/g) that the spectra of the spoiled control samples could be differentiated from spectra of the treated samples with no bacterial growth. Microbial growth is therefore not the only explanation for the spectral variations prior to microbial spoilage. Nonmicrobial, autolytic changes including possible changes in the physical properties are also contributing. Our results show that VIS/NIR spectroscopy can detect autolytic changes occurring in salmon muscle during the early stage of storage, independent of microbial growth. Important spectroscopic changes occur even when microbial growth is not apparent. This indicates that VIS/NIR spectroscopy may be used to determine the degree of freshness before microbial spoilage becomes relevant.

Automated fish bone detection using X-ray imaging

In countries where fish is often consumed, fish bones are some of the most frequently ingested foreign bodies encountered in foods. In the production of fish fillets, fish bone detection is performed by human inspection using their sense of touch and vision which can lead to misclassification. Effective detection of fish bones in the quality control process would help avoid this problem. For this reason, an X-ray machine vision approach to automatically detect fish bones in fish fillets was developed. This paper describes our approach and the corresponding experiments with salmon and trout fillets. In the experiments, salmon X-ray images using 10 × 10 pixels detection windows and 24 intensity features (selected from 279 features) were analyzed. The methodology was validated using representative fish bones and trouts provided by a salmon industry and yielded a detection performance of 99%. We believe that the proposed approach opens new possibilities in the field of automated visual inspection of salmon, trout and other similar fish.

Whey protein-based coatings on frozen Atlantic salmon (Salmo salar): Influence of the plasticiser and the moment of coating on quality preservation

The effects of different whey protein concentrate coating formulations (with or without glycerol or sorbitol in two proportions) on frozen Atlantic salmon quality parameters were evaluated. The influence of the moment of coating application (before or after freezing) was also studied. The coating application after freezing increased the thaw yield, decreased the drip loss, and modified colour parameters of frozen and thawed fillets, in comparison with application before freezing. The moment of coating also influenced the colour of cooked fish fillets. The type of plasticiser affects the colour of thawed and cooked samples, but not the colour of frozen samples. The protein coatings delayed lipid oxidation of salmon fillets, providing better protection against it than water glazing, and this effect was more pronounced when glycerol instead of sorbitol was used in the coating formulation.WPC+glycerol (1:1) coating was the best for frozen Atlantic salmon protection. The sensory properties of salmon fillets were not modified by the use of this coating.

The effects of carbon monoxide on Atlantic salmon ( Salmo salar L.)

Atlantic salmon were exposed to carbon monoxide (CO) before the fish were percussively killed and gill cut. The fish were compared against a control group treated identically, without CO. Salmon exposed to CO expressed no adverse reactions and were easily stunned by percussion. CO-treated salmon had an earlier onset of rigor mortis and a faster decrease in muscle pH than the control group. No significant difference in drip loss was found between salmon treated with CO and the control. A significantly deeper red colour of both gills and fillets of CO-treated salmon was observed 10 days post mortem. Significantly higher levels of plasma lactate and potassium were found in CO-treated salmon compared to control, as well as a lower level of pCO 2. Exposure to CO did not increase plasma cortisol, sodium, haematocrit or glucose; however, lactate was high. Exposure of salmon or other fish to CO could improve quality and welfare when slaughtered.

Sustainable aquafeeds: Progress towards reduced reliance upon marine ingredients in diets for farmed Atlantic salmon ( Salmo salar L.)

The salmon farming industry has been criticised for being a net consumer of marine resources, in the form of fishmeals (FMs) and fish oils (FOs) used in feeds. Despite the efforts made to replace FM and FO with alternatives, such as vegetable proteins and oils, the balance is still generally negative, with calculated fish in–fish out (FIFO) values often being over 4. This paper reports on a FM and FO replacement study, with maximum 20 and minimum 10% FM inclusion in high-energy, extruded salmon feeds, and in which 50% of the feed oil was of vegetable origin (rapeseed). Further, half of the dietary FO was oil reclaimed from fish processing waste (herring offal silage oil), the other half being pristine FO (blend of herring and anchoveta oils). Growth and feed utilisation were assessed in a 9 month trial, during which fish weight increased from ca. 1.2 kg to ca. 4.6 kg. There were no significant differences between feed treatments with respect to growth, feed utilisation and mortality, and replacement of FM with vegetable proteins did not compromise the bioavailability of feed nutrients. Salmon given the feed with the highest level of fishmeal replacement (FM10) had a net production of fillet protein relative to feed input in the form of protein derived from FM, indicating that FM supply is not a major factor that would impose serious limits on the quantity and efficiency of production. The inclusion of FO as 50% of the feed oils ensured that the salmon fillets contained levels of n-3 highly-unsaturated fatty acids (n-3 HUFAs) that would be considered adequate from a consumer perspective (at least 1.5 g n-3 HUFAs per 100 g fillet) and the ratio of n-6 to n-3 fatty acids (ca. 0.65) was also favourable from a human health point of view. There was net consumption of marine fish resources when assessed as FIFO calculated on the basis of the amounts of fish required to produce all FOs (FIFO 3.03–3.59) and on fish needed to produce pristine FOs included in the feeds (FIFO 1.53–1.83). Calculations based upon nutrient ratios gave positive outcomes, and salmon in all treatments deposited more fillet fat than the amount of pristine FO consumed. It is concluded that supplies of FOs impose greater limitations on the formulation of salmon feeds than do supplies of FMs. The results of the study also indicate that increased use of fish processing by-products has the potential to reduce some of the predicted short-fall in FOs resulting from reductions in the amounts of small, pelagic marine fish species rendered directly for the production of FMs and FOs.