• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.409-419
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• 2014

The proximate composition and various specific components of Antarctic krill Euphausia superba, in the catch season between March and August were investigated. Frozen krill were freeze-dried and milled. The proximate composition comprised water, proteins, fats, ash, fatty acids, and amino acids, while the specific components were vitamins, minerals, nucleotides, betaine, and astaxanthin. The moisture content of the krill ranged from 77 to 80%, with the highest value in June, and the ash content was between 12 and 13%. The protein content was lowest in May, and the fat content was 18-19%, with the highest value in March. The amino acid content varied according to the season: taurine and glycine were highest in August; ${\beta}$-alanine was higher in April and May; and arginine, ornithine, and lysine were highest in March. The unsaturated fat content was ~50% and omega-3 fatty acids were highest in June. Oil-soluble vitamins A and E were highest in March, and the water-soluble vitamin content was less than that of oil-soluble vitamins. The mineral content was highest in June, and the most abundant mineral was sodium at 235.60 mg/100 g krill. The content of other minerals was lowest (2.94 mg/100 g) in April, except for lead. The nucleotide content was highest in July, while the betaine content was highest in April and lowest in June. The astaxanthin content was highest in May and ranged from 6 to 10 ppm in other months.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.203-207
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• 2012

The amount of fluoride removed from Antarctic krill via organic acid extraction depends on the extraction time, concentration, extraction volume, and the nature of the acid itself. The fluoride content in Euphausia superba was determined by measuring the concentration of fluoride ion in acidic extracts using an ion-selective electrode. The best results were obtained by adding 50 mL of 0.01 M citric acid to 0.3-0.5 g of krill and extracting for 5 min. Under these conditions, recoveries of fluoride from frozen whole krill and krill meat were 95.6-99.5% and 97.5-101.3%, respectively. The dry basis fluoride contents of krill by-product, krill meat and the boiled krill were 705, 298, and 575 ppm, respectively. These levels were significantly reduced by citric acid extraction.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.999-1005
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• 2018

The purpose of this study was to probe the influences of krill (Euphausia superba) meal with NaF oral administration on a dose-effect relationship between fluoride levels of krill meal and serum enzyme activity such as alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) in rats fed experimental diets for 5 weeks. There were no significant decreases in the activities of ALP, AST, ALT, and LDH in sera among krill meal diet groups (KF10, KF20, KF30). However, these groups were significantly (p<0.05) lower enzyme activities than normal diet (ND) plus NaF 10 mg group (NF). The fluoride levels of serum and organ tissues (liver, brain, heart, lung, kidney) in NaF 10 mg groups (NF, KF10, KF20, KF30) were significantly increased by adding krill meal in comparison with normal diet group. The results indicate that a difficult to found toxicity to the tissues from krill meal diet groups.

• Ocean and Polar Research
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• v.27 no.1
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• pp.75-86
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• 2005

Acoustic survey for density and biomass estimate of Antarctic krill, Euphausia superba, was conducted in the large area between South Shetland Islands and South Orkney Islands, during November 30-December 30, 2002. Considering oceanographic and geographic properties, the study area was divided into six sub-regions. Acoustic system and frequency used in the survey were quantitative echo sounder (Simrad Ek 500) and 38, 120-kHz split beam transducers. In order to discriminate krill aggregations in all acoustic signal, difference of mean volume backscattering strength $({\Delta}MVBS)$ method of the two frequencies was introduced. Averaged krill density for the overall surveyed area was $23.5g/m^2$, and spatially averaged estimates of krill density were $44.9g/m^2$ (north of the South Shetland Islands), $30.3g/m^2$ (Bransfield Strait), $11.3g/m^2$ (near the Elephant Island), $13.6g/m^2$ (north of the Elephant Island), $18.1g/m^2$(between Elephant Island and South Orkney Islands) and $21.7g/m^2$(northwest of the South Orkney Islands) at each sub-area. In the two sub-regions with surveyed area, estimated krill biomass in the north of the Elephant Island was 0.315 million tones with a CV of 18.35% $(6,766mile^2)$, and between Elephant Island and South Orkey Islands was 1.26 million tones with a CV of 9.45% $(20,299mile^2)$. As a whole, the krill density in the early summer season was low level, comparing with that of January-February. This suggested that major krill swarms in the around South Shetland Islands were reached in the mid-summer seasons from western part of the Antarctic Peninsula, and the low krill density also affects the density variation of the krill between Elephant Island and South Orkney Islands.

• Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.15.1-15.9
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• 2018

Background: Inflammation has been known to associate with many human diseases. The objective of this study was to evaluate an anti-inflammatory effect of ozonated krill (Euphausia superba) oil, which was prepared by the treatment of krill oil using ozone gas. The anti-inflammatory activity was evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Results: Ozonated krill oil significantly inhibited nitric oxide (NO) production and suppressed the mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated RAW 264.7 macrophages. Ozonated krill oil also reduced the mRNA expression of inflammatory cytokines such as interleukin (IL)-$1{\beta}$, IL-6, and tumor necrosis factor (TNF)-${\alpha}$ in LPS-stimulated RAW 264.7 macrophages. To elucidate the mechanism underlying the anti-inflammatory activity of ozonated krill oil, we evaluated the effects of ozonated krill oil on the activation of mitogen-activated protein kinases (MAPKs) pathway. Ozonated krill oil suppressed the LPS-stimulated phosphorylation of p38 MAPK and c-Jun N-terminal kinases (JNK). Conclusion: This study revealed that the ozonated krill oil exhibited an anti-inflammatory effect in LPS-stimulated RAW 264.7 macrophages. To the best of our knowledge, this is the first report that ozonated krill oil suppressed pro-inflammatory mediator and cytokine expression in LPS-stimulated RAW 264.7 macrophages by inhibiting the phosphorylation of p38 MAPK and JNK.

• Applied Biological Chemistry
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• v.43 no.4
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• pp.309-313
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• 2000

For the use of Antartic krill(Euphausia superba Dana) as food resource, general composition, extracting condition of chitin and quality characteristics of chitosan were investigated. General composition of frozen krill(Euphausia superba Dana) was consisted of moisture 79.0%, protein 13.1%, lipid 4.0%, VBN 7.7mg%, ash 2.7%, others 1.2% and that of dried krill powder was moisture 5.6%, protein 56.1%, lipid 18.8%, ash 11.4%, others 8.1%. The condition of chitin extraction from krill powder was treated with 1N NaOH at $40^{\circ}C$ for removing protein, 1N HCl for excepting mineral substances and methanol for decoloring. The yield of chitin by new procedure developed was 3.7%. The composition of extracted chitin contents was moisture 7.1%, ash 0.4%, protein 3.5%, lipid 3.1%. The results of degree of deacetylation in chitosan at 50% NaOH, $121^{\circ}C$, for 2 hrs was showed 82%. At the same alkali concentration and reaction concentration, a longer reaction time gave a decreased degree of deacetylation. The apparant viscosity was 0.09241 Pa in 1% chitosan from krill and 0.13826 Pa in standard chitosan.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.4
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• pp.352-358
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• 2022

We explored the frequency response of krill target strength (TS) to understand the Antarctic krill (Euphausia superba) and ice krill (Euphausia crystallorophias) using the stochastic distorted-wave Born approximation (SDWBA) model. The results showed that the distribution of orientation and the fatness factor could significantly impact on the frequency response of TS. Krill TS is clearly depended on acoustic properties, which could affect to estimate the biomass of two krill species. The results provide insight into the importance of understanding TS variation to estimate the Antarctic krill and ice krill biomass, and their ecology related to the environmental features in the Southern Ocean.

• Ocean and Polar Research
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• v.26 no.4
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• pp.679-684
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• 2004

To determine if Antarctic krill employ body shrinkage as one of its overwintering mechanisms in the field, Euphauia superba and Euphausia crystallorophias were collected during fall and winter in and around Marguerite Bay through US Southern Ocean GLOBEC field programs during fall and winter 2001 and 2002. The relationships between the body length and weight of both krill species were exponentially correlated with no significant differences between the two species (p>0.05). The ratio between eye diameter and body length of individual krill was examined in an expectation that it could be used as an indicator of the body shrinkage as previously suggested by Shin and Nicol (2002). These ratios were significantly different between the two krill species. Especially, E . crystallorophias had bigger eyes than E. superba. In both krill species, eye diameters were highly correlated with body lengths (regression coefficients ${\geq}0.70$). For E. crystallorophias, no significant differences of the ratio of eye diameter/body length were detected between fall and winter. Even though the ratios for E. superba were seasonally varied, it was not clear whether body shrinkage was an actual and critical overwintering mechanism for the krill population found in this study area. These results suggest that some individuals of E. superba might experience the body shrinkage during a part of their liff, but this morphological index alone (eye diameter/body length) may be insufficient to unambiguously separate the shrunk krill from the non-shrunk ones in the field-collected animals.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.938-946
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• 2017

This study was conducted to examine the changes in serum lipid components and blood glucose by krill (Euphausia superba) meal and sodium fluoride (NaF) in rats fed on experimental diets and administered orally to NaF 10 mg for 5 weeks. Body weight of rats decreased as the amount of krill meal diet increased, it was observed the basal diet plus NaF group (BF group) compared to the lower basal diet group (BD group). The serum concentrations of total cholesterol, LDL (low-density lipoprotein) cholesterol, free cholesterol, triglyceride (TG), phospholipid (PL) and blood glucose in serum were higher in the BF group than the 10% krill meal group plus NaF 10 mg (KF10 group) or BD group, the 20% krill meal plus NaF 10 mg group (KF20 group), the 30% krill meal plus NaF 10 mg group (KF30 group). Conversely depending on the content of krill meal for the HDL (high-density lipoprotein) cholesterol level, it showed higher results. The concentration of total protein was no significant difference among the groups (p<0.05). The results indicate that a krill meal diet effectively inhibited increases in lipid elevation and blood glucose level in the sera of rats.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.318-324
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• 2016

Commercial split beam echosounder (ES70) installed on a krill fishing vessel was calibrated in order to utilize it in estimating biomass of Antarctic krill (Euphausia superba). The method of calibration was to analyze the difference between the bottom backscattering strength of the commercial split beam echosounder (i.e. ES70) and the scientific echosounder (i.e. EK60) at one of transects near South Shetland Islands designated by CCAMLR. 38 kHz and 120 kHz were used for the calibration, and krill swarm signal levels obtained from multi frequencies, was examined to verify the calibration result. The analysis result indicated possibility of calibration by bottom backscattering strength, since the proportion of krill swarm signals within 2 dB < $S_{V\;120\;kHz-38\;kHz}$ < 12 dB (i.e. a common $S_{V\;120\;kHz-38\;kHz}$ range of 38 kHz and 120 kHz to be an indicator of Antarctic krill) over the total acoustic signals were 26.95% and 92.04%, respectively before and after the calibration.