Salmon Flesh Research Articles

Lures

Lures Jennifer Atkinson (bio) Off the starboard bow at 4 A.M.: Barred cloud and scaled-gold backlight, A musical staff—all but blank to score the near silence: Waves slop, ice clunks, an otter takes a breath. Just under the ripple- and chop-flustered surface, A lion's-mane jellyfish hangs in the slack tide, its stingers trailing like lures. Nothing out there to note—thank God— The crank-up and fly-wheel jerked pulse of my own noisy mind. From wilderness to wilderness, tide to tide— What is it I long for? What is it I have? Sunlight the color of raw salmon flesh, A knife edge of ridge line, ice honed. Jennifer Atkinson Jennifer Atkinson is the author of two books of poems, The Dogwood Tree and The Drowned City. She teaches creative writing at George Mason University. Copyright © 2007 The Curators of the University of Missouri

Inter-individual variation in total fatty acid compositions of flesh of Atlantic salmon smolts-fed diets containing fish oil or vegetable oil

Fish such as Atlantic salmon (Salmo salar L.) are a natural source of n-3 highly unsaturated fatty acids (HUFA) eicosapentaenate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3), which are essential for protecting humans against cardiovascular diseases. Thus, flesh n-3 HUFA level is a trait of considerable importance in farmed fish, particularly now that the fishmeal and fish oil (FO) components of traditional aquaculture diets have to be replaced by more sustainable alternatives including plant meals and vegetable oils (VO). The present study aimed to characterize the inter-individual variation in this trait in a single strain of Atlantic salmon. Fish were grown for 12 weeks on either an FO diet, or a diet with 100% of the FO replaced by a VO blend containing rapeseed, linseed and palm oils, flesh n-3 HUFA content and composition determined, and the variation between individuals characterized. The results showed that, irrespective of diet, variation exists in the content of n-3 HUFA in the flesh of individual salmon, showing that individual animals can display an enhanced ability to maintain high levels of n-3 HUFA in their flesh. The pros and cons of defining the trait on a qualitative or quantitative basis are discussed.

Varying effects of anadromous sockeye salmon on the trophic ecology of two species of resident salmonids in southwest Alaska

Summary1. Anadromous salmon transport marine‐derived nutrients and carbon to freshwater and riparian ecosystems upon their return to natal spawning systems. The ecological implications of these subsidies on the trophic ecology of resident fish remain poorly understood despite broad recognition of their potential importance.2. We studied the within‐year changes in the ration size, composition and stable isotope signature of the diets of two resident salmonids (rainbow trout, Oncorhynchus mykiss; Arctic grayling, Thymallus arcticus) before and after the arrival of sockeye salmon (Oncorhynchus nerka) to their spawning grounds in the Bristol Bay region of southwest Alaska.3. Ration size and energy intake increased by 480–620% for both species after salmon arrived. However, the cause of the increases differed between species such that rainbow trout switched to consuming salmon eggs, salmon flesh and blowflies that colonized salmon carcasses, whereas grayling primarily ate more benthic invertebrates that were presumably made available because of physical disturbances by spawning salmon.4. We also observed an increase in the δ15N of rainbow trout diets post‐salmon, but not for grayling. This presumably led to the observed increase in the δ15N of rainbow trout with increasing body mass, but not for grayling.5. Using a bioenergetics model, we predicted that salmon‐derived resources contributed a large majority of the energy necessary for growth in this resident fish community. Furthermore, the bioenergetics model also showed how seasonal changes in diet affected the stable isotope ratios of both species. These results expand upon a growing body of literature that highlights the different pathways whereby anadromous salmon influence coastal ecosystems, particularly resident fish.

A case of Diphyllobothrium latum infection with a brief review of diphyllobothriasis in the Republic of Korea

A case of Diphyllobothrium latum infection in a 49-year old man is described, and diphyllobothriasis latum in the Republic of Korea is briefly reviewed. An incomplete strobila of a tapeworm, 95 cm in length, without scolex and neck, was spontaneously discharged in the feces of a patient. On the basis of morphologic characteristics of the worm and eggs, the worm was identified as D. latum. The patient was successfully treated with a single dose (15 mg/kg) of praziquantel. The most probable source of infection was salmon flesh according to the past history of the patient. The first case of D. latum infection was documented in 1971, and this is the 43rd recorded case in the Republic of Korea. The 43 cases were briefly reviewed. The patientso main complaints were gastrointestinal troubles, such as mild abdominal pain, indigestion, and diarrhea, and discharge of tapeworm segments in the feces. The suspected infection sources included raw or improperly cooked flesh of fresh or brackish water fish, including the perch, mullet, salmon, and trout.

Natural and synthetic pigments used in the pink-red coloration of salmon flesh: methodology of quali-quantitative assessments and sampling results

In Europe Atlantic salmon leads the first position in the farmed species contest with more than 763,000t (FES, 2007). In the year 2006, Norway produced alone beyond 603,000t followed by the United Kingdom with 128,000t. In these last years, the demand of organic salmon is gradually increased both in domestic and foreign markets. In these fish the pink-red coloration of flesh is obtained by supplementing the feed with shrimp waste meal. In Italy, Coop Italia since three years has started the commercialization in the context of “prodotti a marchio” of Atlantic salmon farmed following prescriptions reported in terms of specification that prohibits the use of synthetic and GM pigments in the feeds. In collaboration with this supermarket company, the Faculty of Veterinary Medicine of Camerino University carried out the quali-quantitative assessments on the presence of molecules and relative isomers that distinguish the natural carotenoid pigment from the synthetic one. Skinned portion of fillet (10g) were collected from dorsal muscle (retro-cranial, central and caudal region), mixed and homogenized and repeatedly extracted with acetone until they were colourless. The pooled extract were filtered and an aliquot (10ml) was centrifugated (2200xg, 5min). The astaxanthin content in the supernatant was determined by HPLC using a Varian ProStar instrument equipped with UV/vis detector using an external astaxanthin standard at detection wavelength 470nm. Analysis was performed on a Varian Kromasil 100 C 18 250x0.3 mm according to Bjerkeng et al. (1997). Identification and determination of stereoisomers were carried out by means of a Sumichiral a-phenylglicine 250x4.6mm column following Abu-Lafi and Turujman method (1999). The analysis performed on all the organic fish have demonstrated the exclusive content of natural pigment. In this group (b.w.=3.9-4.4kg), C-Card for salmonids ranged between 26±1 in 2004 and 21.5±1.3 in 2005 and 21.5±2.1 in 2006. Astaxanthin and isomers decreased from 5.6±0.3mg/kg in 2004 to 2.9±1.1mg/kg in 2006. The low-cost non organic salmon group (b.w.=4.5-4.6kg) resulted pigmented only with synthetic carotenoids and C-card for salmonids ranged between 27.3 in 2004 and 23.7 in 2005 whereas in 2006 it was observed equal to 27. Also in this batch, astaxanthin and isomers decreased passing from 6.5mg/kg in 2004 to 4.9mg/kg in 2006.

Flesh Quality of Market-Size Farmed and Wild British Columbia Salmon

This study compared the flesh quality of farmed and wild sources of British Columbia (BC) salmon with respect to concentrations of polychlorinated biphenyl compounds, polychlorinated dibenzodioxins/dibenzofurans and their associated toxic equivalents, total mercury (THg), methylmercury (MeHg), and selected fatty acids of known importance for human health viz., omega-3 (n-3) highly unsaturated fatty acids (n-3 HUFAs) and (n-6) fatty acids. Skinned fillets from known sources of farmed Atlantic, coho, and chinook salmon (n = 110) and wild coho, chinook, chum, sockeye, and pink salmon (n = 91) were examined. Atlantic salmon contained higher PCB concentrations (means, 28-38 ng/g) than farmed coho or chinook salmon, and levels in these latter species were similar to those in wild counterparts (means, 2.8-13.7 ng/g). PCB levels in Atlantic salmon flesh were, nevertheless, 53-71-fold less than the level of concern for human consumption of fish, i.e., 2000 ng/g as established by Health Canada and the U.S. Food and Drug Administration (US-FDA). Similarly, THg and MeHg levels in all samples were well below the Health Canada guideline (0.5 microg/g) and the US-FDA action level (1.0 microg/g). On average, THg in farmed salmon (0.021 microg/g) was similar to or lower than wild salmon (0.013-0.077 microg/g). Atlantic salmon were a richer source (mean, 2.34 g/100 g fillet) of n-3 HUFAs than the other farmed and wild sources of salmon examined (means, 0.39-1.17 g/100 g). The present findings support the recommended weekly consumption guidelines for oily fish species (includes all BC salmon sources) for cardio-protective benefits as made by the American Heart Association and the UK Food Standards Agency.

Salmon mortalities associated with a bloom of Alexandrium fundyense in 2003 in the Bay of Fundy, and subsequent early warning approaches for industry

In early September 2003, >3.0 × 105 cells l−1 of Alexandrium fundyense were detected in close proximity to salmon aquaculture sites near Grand Manan Island in the Bay of Fundy, eastern Canada. High concentrations persisted throughout the month, peaking to >8 × 105 cells l−1 on 18 September. Concurrently, some salmon farms in the area experienced elevated mortalities. Although the cause of mortality is not yet fully understood, it appears to be related to the high concentrations of A. fundyense. Paralytic shellfish poisoning toxins were not detected in the edible flesh of salmon (by mouse bioassay and high-performance liquid chromatography), but were detected at low levels in viscera and gills. Blue mussels Mytilus edulis analysed from areas affected by the bloom reached levels of 18 000μg STX equivalents 100g−1 of tissue. As a result of the salmon mortalities, a project was initiated to establish a monitoring approach for harmful algal blooms to provide an early warning of potential events and to act as a tool for mitigation actions.

Muscle and flesh quality traits in wild and farmed Atlantic salmon

Muscle characteristics that are important for flesh quality traits were assessed in populations of wild and farmed Atlantic salmon ( Salmo salar L.). The wild fish were obtained from a commercial fishery on the North Esk, Scotland in 2001 and 2003. The farmed fish comprised 7 families from the Stofnfiskur breeding programme (Stofnfiskur A/S, Iceland) grown in 5 m × 5 m × 5 m net pen sea cages in a dedicated trial unit on South Uist, Scotland. Total carotenoid pigment (mg kg − 1 wet mass flesh) concentrations were higher in farmed (7.68 and 8.43 for grilse and salmon, respectively) than wild fish (5.53 and 6.44 for grilse and salmon, respectively). In contrast, the average flesh colour, measured with a SalmonFan™, was similar for all groups (27.4 to 28.0), indicating a superior colour visualisation per unit pigment concentration in wild fish. The flesh lipid content was 46%-higher (grilse) and 84%-higher (salmon) in farmed than wild fish. Vitamin E concentrations per unit wet mass lipid were similar in wild and farmed salmon and in the range (208–259 mg kg − 1 ). Fillet firmness was measured using a shear test and instrumental texture analyser. The work done (WD) to shear standardised post-rigor muscle samples was higher in grilse than salmon and was significantly greater for the wild (710 and 811 mJ, respectively) than farmed (415 and 602 mJ, respectively) fish, indicating a firmer texture in the wild fish. The grilse and salmon sampled had stopped recruiting fast muscle fibres and both wild and farmed fish had around 650,000 fibres per trunk cross-section. Thus differences in fillet texture and colour between these populations could not be explained by the muscle cellularity which was similar between groups. Hydroxyproline (HYP) was used to estimate collagen concentration. Alkaline-insoluble HYP was 72.5% higher in wild than farmed salmon (14.0 vs. 8.1 μmol g − 1 dry mass, respectively) whereas alkaline-soluble HYP was 5.2-fold higher in farmed than wild salmon (31.0 vs. 6.0 μmol g − 1 dry mass, respectively). The alkaline-insoluble collagen fraction is thought to be enriched with reducible and non-reducible cross-linked collagen. There was a significant positive correlation between pyridinoline (PYD) crosslink concentration and WD, explaining 25% of the within population variation in firmness. However, PYD concentration (pmol g − 1 dry mass) was similar between wild (476) and farmed (445) salmon and cannot explain the differences in flesh firmness observed between populations. It was hypothesised that the higher average values of firmness in the wild than farmed salmon flesh can in part be attributed to higher concentrations of reducible immature collagen crosslinks.

Carbon paste biosensor for phenol detection of impregnated tissue: modification of selectivity by using β-cyclodextrin-containing PVA membrane

In order to detect and quantify with a biosensor the phenol contents in animal tissue (salmon flesh) by simple contact, we have undertaken experimental study on nonwoven cellulose fibers soaked with phenolic compounds. An electrochemical biosensor made of carbon paste and tyrosinase mixed together with electropolymerized pyrrole was elaborated. Phenol detection was realized by electrochemical reduction of quinones produced by the tyrosinase activity. The biosensor was first optimized based on enzyme loading and nature of the carbon paste. A semipermeable membrane containing cyclodextrin moieties was deposited on the biosensor in order to test its sensitivity for phenol detection. Finally, the biosensor was put in contact with phenol absorbing cellulose fibers. Results showed that the relaxation time response of the sensor was relevant of phenol concentration.

Tailoring of Atlantic Salmon (Salmo salar L.) Flesh Lipid Composition and Sensory Quality by Replacing Fish Oil with a Vegetable Oil Blend

Atlantic salmon (Salmo salar L.) juveniles were fed either 100% fish oil (FO), 75% vegetable oil (VO), or 100% VO throughout their life cycle to harvest weight followed by a finishing diet period when all groups were fed 100% FO. The two experimental VO diets were tested at two different locations (Scotland and Norway) against the same control diet (100% FO). The VO blend was composed of rapeseed oil, palm oil, and linseed oil using capelin oil as a control for fatty acid class compositions. Flesh fatty acid profiles were measured regularly throughout the experiment, with the times of sampling determined by changes in pellet size/lipid content and fish life stage. Growth and mortality rates were not significantly affected by dietary fatty acid compositions throughout the life cycle, except during the seawater winter period in Norway when both growth and protein utilization were increased in salmon fed 100% VO compared to 100% FO. Flesh fatty acid composition was highly influenced by that of the diet, and after the finishing diet period the weekly intake recommendations of very long chain n-3 polyunsaturated fatty acid (VLCn-3 PUFA) for human health were 80 and 56% satisfied by a 200 g meal of 75% VO and 100% VO flesh, respectively. No effect on flesh astaxanthin levels was observed in relation to changing dietary oil sources. Sensory evaluation showed only minor differences between salmon flesh from the dietary groups, although prior to the finishing diet period, flesh from 100% VO had less rancid and marine characteristics and was preferred over flesh from the other dietary groups by a trained taste panel. After the finishing diet period, the levels of typical vegetable oil fatty acids in flesh were reduced, whereas those of VLCn-3 PUFA increased to levels comparable with a 100% FO fed salmon. No differences in any of the sensory characteristics were observed between dietary groups. By blending VOs to provide balanced levels of dietary fatty acids, up to 100% of the fish oil can be replaced by the VO blend without compromising growth or flesh quality. At the same time, 75% of the dietary fish oil can be replaced without compromising flesh VLCn-3 PUFA content, thereby providing a beneficial nutritional profile for human consumption.

Textural and physicochemical changes in salmon ( Salmo salar) treated with commercial liquid smoke flavourings

The textural and physicochemical properties of fillets of farmed Atlantic salmon ( Salmo salar) treated with two commercial liquid smoke flavourings (LS1 and LS2) were examined after 15, 30 and 45 days of storage at 2 °C in oxygen impermeable bags. Salmon flesh treated with LS1 was characterized by high water-soluble protein, fat and moisture contents, plus low hardness, fracturability, gumminess and chewiness, and a low alkali-insoluble protein content. These characteristics were similar to those of control salmon (not treated with liquid smoke flavouring). Storage time changed these properties similarly in both. Salmon flesh treated with LS2 was characterized by high hardness, fracturability, gumminess, chewiness and alkali-insoluble protein levels, plus low water-soluble protein, fat and moisture contents. Storage time appeared to have a far less important effect on salmon flesh treated with LS2.

Influence of dietary conjugated linoleic acid (CLA) on lipid and fatty acid composition in liver and flesh of Atlantic salmon ( Salmo salar)

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) on lipid and fatty acid metabolism in Atlantic salmon. The overall objective being to test the hypotheses that CLA has beneficial effects in salmon including growth enhancement, improved flesh quality through decreased adiposity and lipid deposition thereby minimising detrimental effects of feeding high fat diets, and increased nutritional quality through increased levels of beneficial fatty acids including n − 3 highly unsaturated fatty acids (HUFA) and CLA itself. Salmon smolts were fed diets containing two levels of fish oil (low, ∼18% and high, ∼34%) containing three levels of CLA (a 1 : 1 mixture of 9- cis, trans-11 and trans-10, cis-12. at 0, 1 and 2% of diet) for 3 months and the effects on growth performance, liver and muscle (flesh) lipid contents and class compositions, and fatty acid compositions determined. The diets were also specifically formulated to investigate whether the effects of CLA, if any, were more dependent upon absolute content of CLA in the diet (as percentage of total diet) or the relative level of CLA to other fatty acids. Dietary CLA in salmon smolts had no effect on growth parameters or biometric parameters. However, there was a clear trend of increased total lipid and triacylglycerol contents in both liver and flesh in fish fed CLA, particularly in fish fed the high oil diets. Finally, CLA was incorporated into tissue lipids, with levels in flesh being 2-fold higher than in liver, but importantly, incorporation in liver was at the expense of saturated and monounsaturated fatty acids whereas in flesh it was at the expense of n − 3HUFA.

Optimizing Gas Mixtures for Modified Atmosphere Packaging of Fresh King Salmon (Oncorhynchus tshawytscha)

Researchers have evaluated the effect of modified atmosphere packaging (MAP) on the shelf life of fish products. However, there is little published basis for recommended gas mixtures. Most studies have examined the effects of empirical evidence of gas mixes on particular species, but they cannot be used to predict the effect of different gas mixes on shelf life. Further, while the fish:gas ratio has been shown to be a key determinant of bacterial growth under MAP, most studies did not control this parameter. The aim of our research was to optimize gas mixes and fish:gas ratios for the MAP storage of king salmon. Flesh portions from defined fillet positions were placed on drip pads and boxed, giving a standardized nominal volume of 27.4 cm3 and an exposed surface area of 14.4 cm2. Each sample was placed in a foil barrier bag containing an oxygen absorber. Controlled volumes (0-100 cm3) of CO2 or 100 cm3 of a 40:60 mixture of CO2:N2 were then hand-injected through a septa. Bags were stored in melting ice (0 ± 0.05°C) and analyzed after 0, 8, 22 and 90 days for headspace CO2 and O2, EH, fish freshness meter (Distell, West Lothian, Scotland) reading, drip loss, texture, raw and cooked sensory characteristics, microbial numbers, bacterial flora composition, total volatile base nitrogen (TVBN) and ATP derivatives. High CO2 levels reduced bacterial counts, but resulted in poor cooked sensory characteristics due to carbonated flavor. We calculated the threshold level of CO2 at which this could be detected by our trained panel. We also determined the solubility of CO2 in salmon flesh and calculated Henry's constant to resolve the relationship between gas mixes and the fish:gas ratio. We now have the basis of a simple mathematical model optimizing these to give maximum shelf life and sensory acceptability.

Selective extraction of astaxanthin from crustaceans by use of supercritical carbon dioxide

An on-line supercritical fluid extraction (SFE) system coupled to a continuous flow manifold including a UV detector was used as a screening system to extract astaxanthin from crayfish, which was found to be the major carotenoid present in the samples. This compound constitutes the principal additive used to dye salmon flesh. The flow manifold was used to confirm the presence of astaxanthin in the crustacean samples. Also, an HPLC/UV–vis method was used to ascertain that this compound was the major carotenoid extracted under the optimum SFE conditions employed. The influence of SFE operating variables such as pressure, temperature, equilibration time, extraction time, trap temperature, and volume of CO2 modifier was examined in order to maximize the efficiency of analyte extraction. The use of supercritical CO2 enables the expeditious, selective, quantitative extraction of astaxanthin from crustaceans.

Dietary uptake of dioxins (PCDD/PCDFs) and dioxin-like PCBs in Atlantic salmon (Salmo salar)

Summary Atlantic salmon (Salmo salar) were fed graded levels of dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) and dioxin-like polychlorinated biphenyls (DLPCBs) in their diets for 7 months. The dioxin and DLPCB concentrations in both fillet and whole body of salmon increased with increasing dietary exposure. DLPCBs transferred more efficiently from the feed to edible flesh of salmon than dioxins, and contributed a higher proportion to the total toxic equivalents (TEQ). At the end of the trial, the maximum concentrations of dioxins in fillet and whole fish were 1.9 and 2.3 pg WHO-TEQ g−1 fresh weight, respectively. Hence with this feeding period even with the most contaminated feed (4.9 pg WHO-TEQ g−1 dw) the dioxin concentrations in salmon did not exceed the maximum level set by the European Commission [4 pg WHO-TEQ g−1 (EC 2375/2001)]. The inclusion of DLPCBs in this study provides valuable information for forthcoming risk assessments and the future establishment of maximum limits for these compounds in feed and fish.

Selective extraction of astaxanthin from crustaceans by use of supercritical carbon dioxide

An on-line supercritical fluid extraction (SFE) system coupled to a continuous flow manifold including a UV detector was used as a screening system to extract astaxanthin from crayfish, which was found to be the major carotenoid present in the samples. This compound constitutes the principal additive used to dye salmon flesh. The flow manifold was used to confirm the presence of astaxanthin in the crustacean samples. Also, an HPLC/UV–vis method was used to ascertain that this compound was the major carotenoid extracted under the optimum SFE conditions employed. The influence of SFE operating variables such as pressure, temperature, equilibration time, extraction time, trap temperature, and volume of CO2 modifier was examined in order to maximize the efficiency of analyte extraction. The use of supercritical CO2 enables the expeditious, selective, quantitative extraction of astaxanthin from crustaceans.

Texture, gaping and colour of fresh and frozen Atlantic salmon flesh as affected by pre-slaughter iso-eugenol or CO 2 anaesthesia

Farmed Atlantic salmon ( Salmo salar L.) were slaughtered at an average weight of 5.5 kg in May 2001 under either traditional CO 2 anaesthesia (denoted high stress) or a two-step iso-eugenol anaesthesia (denoted low stress) before being bled to death in chilled seawater. Product quality analyses were performed on fillets after 5 days on ice and on cutlets after 12 months of frozen storage (−25 °C). In ice-stored fillets, no differences in gaping were observed between the two anaesthetic protocols, but instrumental analyses revealed that the flesh of the salmon exposed to CO 2 sedation was softer and slightly redder (higher a*-value, 27.1±0.1, S.E. versus 26.4±0.1, p<0.0004) and more yellowish (higher b*-value, 22.6±0.1 versus 22.0±0.1, p<0.0001) than the salmon anaesthetised using iso-eugenol. Analyses of frozen–thawed cutlets confirmed the fresh fillet results in that salmon anaesthetised using iso-eugenol were firmer and paler (RocheSalmoFan™ score, 23.5±0.4 versus 24.4±0.3, p<0.05) than the salmon anaesthetised using CO 2. Furthermore, the frozen and thawed cutlets of iso-eugenol-anaesthetised salmon had a higher muscle pH (6.15±0.01 versus 5.98±0.03, p<0.05) and lower liquid loss (5.1±0.3 versus 7.1±0.3, p<0.05). Individual growth rate, final body weight (BW), final body length, condition factor (CF), sex, gonadosomatic index (GI) were also registered. No significant correlations ( p>0.15) between these growth and body conformation variables and gaping or fillet softness were detected. In conclusion, no differences were observed in fillet gaping between the two anaesthetic protocols, but the salmon anaesthetised using iso-eugenol were firmer, paler and had a higher water-holding capacity than salmon exposed to CO 2 anaesthesia.

Estimates of phenotypic and genetic parameters for flesh colour traits in farmed Atlantic salmon based on multiple trait animal model

Three different methods of colour measurement of Atlantic salmon flesh were employed in this study; subjective scoring (SalmoFan™), colorimetric measurement and carotenoid content as measured by NIR analysis. Parentage of fish was assigned using a suite of eight microsatellite markers. Genetic parameters were estimated using a restricted maximum likelihood methodology applied to a multivariate animal model. Heritabilities for all colour traits were low to medium with carotenoid content in the flesh exhibiting the lowest additive genetic variation. Genetic correlations between carotenoid content and perceived and colorimetric traits were also lower than all other genetic correlations suggesting that the retention of pigment is not under the control of the same genes as perceived colour. It may be that fillet colour is influenced by factors other than pigment retained in the flesh. Genetic correlations between subjective visual scores (two scorers) and colorimetric measurements were all high with the a* value of the Minolta camera being the most highly correlated with subjectively assessed colour.

Increased individual growth rate and community biomass of stream insects associated with salmon carcasses

We showed that salmon carcass tissue can increase the growth rate of individual caddisflies as well as increase the local biomass of the aquatic insect community in 3 major stream habitat types. Sixteen insect taxa were found on salmon carcasses. The 7 dominant taxa in terms of biomass all had greater biomass in containers baited with salmon flesh in all habitats sampled; however, only 5 showed a significant salmon effect at the Bonferroni adjusted α of 0.007. The larval growth of Ecclisomyia conspersa was significantly greater on salmon muscle tissue than on conditioned leaves. Asynarchus pacificus grew significantly better with a combination of salmon and conditioned leaves than with either conditioned leaves or salmon muscle tissue alone. Our findings contribute to the understanding of the transfer of marine nutrients between generations of salmonids via aquatic insects, which are important prey items of juvenile salmonids.

Application of Quality Index Method (QIM) Scheme in Shelf‐life Study of Farmed Atlantic Salmon (Salmo salar)

ABSTRACTSalmon (Salmo salar) was stored in ice up to 24 d, and changes during storage were observed with sensory evaluation using the Quality Index Method (QIM), and Quantitative Descriptive Analysis (QDA), total viable counts (TVC), hydrogen sulfide (H2S)‐producing bacteria, and instrumental texture measurements (compression test). Maximum storage time in ice was determined with QDA and fat content by Soxhlet extraction. A high correlation between QIM and storage time in ice was found. Storage time could be predicted with ± 2 d. TVC increased exponentially with storage and was dominated by H2S‐producing bacteria after 20 d in ice, which was the maximum storage time. Texture measurements indicated softening of salmon flesh with storage.