• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.439-446
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• 1985

This study was designed to compare the lipid components among wild and cultured eel, Anguilla japonica, and conger eel, Astroconger myriaster. The lipid components of cultured eel were analyzed and compared with those of wild and conger eel. In the content of total lipid, the lipid content in cultured eel was slightly higher than that in wild one, but 2 times higher than that in conger eel. The lipid contents in edible portion of wild and cultured eel were 5 times higher than those in viscera, but the lipid content in edible portion of conger eel showed a similar trend to that in viscera. In the fatty acid composition of neutral lipid in edible portion, percentages of $C_{14:0},\;C_{16:0}\;and\;C_{18:1}$ in cultured eel were higher than those in wild one, while percentages of $C_{16:1},\;C_{18:2},\;C_{18:3},\;C_{20:4},\;C_{20:5},\;C_{22:5}\;and\;C_{22:6}$ lower, and percentages of $C_{18:0},\;C_{20:4}\;and\;C_{22:6}$ in conger eel were noticeably higher than those in wild and cultured eels. In the case of phospholipid in edible portion, percentages of $C_{18:0}\;and\;C_{18:2}$ in cultured eel were higher than those in wild one, while percentages of $C_{16:0},\;C_{16:1},\;C_{18:1},\;C_{18:3},\;C_{20:4},\;C_{20:5},\;C_{22:5}\;and\;C_{22:6}$ lower. The unsaturation (TUFA/TSFA) of neutral lipid was no significant difference among wild and cultured eel, and conger eel, but that of phospholipid in wild eel was higher than that in cultured eel and conger eel. The essential fatty acid content(TEFA) of neutral lipid in edible portion of wild eel was 3 times higher than that of cultured one. but the TEFA of phospholipid in edible portion was no significant difference among wild and cultured eels, and conger eel. The w3 highly unsaturated fatty acid content (w3 HUFA) of neutral lipid in edible portion of wild eel was 2.0 to 2.5 times higher than that of cultured eel and conger eel, but the w3 HUFA of phospholipid in edible portion of wild eel was noticeably higher than that of cultured eel and conger eel. In the ratio (A/B) of fatty acid content (A) in cultured eel to that (B) in diet, the A/B ratios of $C_{18:2}\;w6,\;C_{18:3}\;w3,\;C_{20:5}\;w3\;and\;C_{22:6}\;w3$ were 0.23 to 0.48 much lower than the other fatty acid. Consequently, it is considered that the ratios of w3 HUFA is related to the biosynthesis of polyenoic acid and growth rate of cultured eel.

• Development and Reproduction
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• v.16 no.4
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• pp.289-294
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• 2012

Gene expressions of cytochrome P4501A (CYP1A), aryl hydrocarbon receptor (AhR) and vitellogenin (Vg) by endocrine disruptors, benzo[${\alpha}$]pyrene (B[a]P) and tributyltin (TBT) were examined in cultured eel hepatocytes which were isolated from eels treated previously with B[a]P (10 mg/kg) or estradiol-$17{\beta}$ (20 mg/kg) in vivo, and the relationship between CYP1A, AhR and Vg genes were studied. When the cultured eel hepatocytes were treated with B[a]P ($10^{-6}-10^{-5}M$) the gene expressions of CYP1A and AhR were enhanced in a concentration-dependent manner. However, when treated with TBT ($10^{-9}-10^{-5}M$) the gene expressions of CYP1A and AhR were suppressed at high concentrations ($10^{-6}-10^{-5}M$), while having no effects at low concentrations ($10^{-9}-10^{-7}M$). Gene expression of Vg was also suppressed by TBT in a concentration-dependent manner in cultured eel hepatocytes which was previously treated in vivo with estradiol-$17{\beta}$.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1573-1580
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• 2016

The disease occurred in cultured eel (Anguilla japonica) in a recirculatory culture system without any separated filtration apparatus. As the pond had a high level of nitrite with $60mg/{\ell}$, 1% NaCl was added to reduce nitrite toxicity to eel. The first outbreak was observed a week after the NaCl treatment and continued for 10 days. Accumulated mortality was about 0.2-0.5%. Affected fish ranged from 150-350 g were usually anorexic and exhibited yellow colour in the skin of the abdominal region and at the base of pectoral fins, as well as in the eyes. In a few individuals with severe symptoms, the lateral skin was also yellowish. The spleen, kidney, muscle and gall bladder were yellowish and the liver was pale-yellow colour but green on the posterior part. The gall bladder was shrunken without bile. Some abnormal erythrocytes such as "tear drop" cells (dacrocyte) were observed in peripheral blood smears stained with May-Grunwald Giemsa. Hematocrit values and hemoglobin contents in the jaundiced eel were significantly lower compared with apparently heathy eel. Severe haemosiderosis accompanied by erythrophagocytosis was found in the kidney and spleen. Haemosiderin deposits were observed in macrophages of the haematopoietic tissue of the kidney and in the splenocytes. But no significant alterations were found in the hepatic cells. In this study we report the first outbreak of jaundice in cultured eel in Korea. Pathological and hematological investigations suggested that severe hemolysis may resulted in jaundice in eel although the cause of hemolytic jaundice was not identified in this study.

• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.85-92
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• 2013

To determine the relative importance of two main factors, diet or culture environment, that affect the proximate composition and main nutritive ingredients (vitamin A, vitamin E, cholesterol, fatty acid composition) in cultured eels, we analyzed the composition of eels fed diets of formula feed (FF) produced by four different companies and of eels cultured at five different eel farms that provided only one of the four different FFs. The four commercial eel FFs did not markedly differ in proximate composition or major nutritive compounds, and consequently, these variables did not significantly differ in cultured eels fed the different FFs. The FF imported from Japan was marginally superior to the two domestic commercial FFs and the FF imported from Taiwan in terms of the proximate composition and main nutritive ingredients of both the FF itself and the eels cultured on it. However, proximate composition and main nutritive ingredients significantly differed among eels cultured at the five farms that used a different FF and among eels fed the four different FFs at the same farm. In conclusion, the difference in quality between domestic and Japanese FFs in terms of eel culture was small, whereas physical or chemical environmental differences among farms during eel culture may more strongly affect the proximate composition and levels of the main nutritive ingredients in cultured eels.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.60-66
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• 1986

The muscles of wild and cultured eel, Anguilla japonica, were analyzed for the protein composition and amino acid profile. The differences of the subunit distribution for the sarcoplasmic and myofibrillar proteins were discussed with sodium dodecylsulfate(SDS) polyacryamide gel electrophoresis. The muscle protein in wild eel was composed of $30.78\%$ of sarcoplasmic, $59.02\%$ of myofibrillar, $9.73\%$ of residual intracellular and $2.47\%$ of stroma fraction. That in cultured eel was composed of $31.81\%,\;58.37\%,\;8.16\%\;and\;1.80%$, respectively, The sarcoplasmic and myofibrillar proteins were composed of 16 and 14 subunits in wild eel, and 22 and 15 subunts in cured eel. The sarcoplasmic protein between wild and cultured muscles showed a similar trend in the subunits, except a few subunits such as 36,500, 46,000, 58,500, 75,000, 170,000 and 235,000 daltons in cultured eel. Only the existence of 45,000 dalton subunit was the difference between wild and cultured eel in myofibrillar protein. The distribution patterns of total amino acid in muscles of wild and cultured eel were found to be very similar trend, although glycine content in wild eel was slightly higher than that in cultured one.

• Journal of Food Hygiene and Safety
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• v.20 no.2
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• pp.98-102
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• 2005

As a part of basic investigation for utilizing cultured eel and by-products as a food source, a mineral contents and fatty acid composition of bone and flesh were investigated. Flesh of cultured eel was higher in moisture and crude protein content, and lower in crude ash and lipid content than those of the bone. Mineral of bone were measured 220.72 mg/100 g of Ca, 169.87 mg/100 g of P, 117.05 mg/100 g of Na,92.75 mg/100g of K, 6.18 mg/100g of Cu,5.02 mg/100 g of Zn,2.56 mg/100 g of Fe, and flesh were measured 120.23 mg/100g of CL 150.36 mg/100 g of P, 136.36 mg/100 g of Na, 89.36 mg/100 g of K, 4.02 mg/100 g of Cu, 1.71 mg/100 g of Zn,2.03 mg/100 g of Fe. The major fatty acid in bone and flesh of cultured eel were generally oleic acid $(44.40\%, 43.76\%)$, palmitic acid $(24.19\%,\;21.30\%)$, palmitoleic acid $(8.18\%,\;7.72\%)$, eicosapentaenoic acid $(5.72\%,\;6.65\%)$, myristic acid $(3.96\%,4.34\%)$ in order. The fstty acid composition of total lipid was no significant difference among bone and flesh of cultured eel, However, bone of cultured eel revealed higher content in saturated and monounsaturated fatty acid, while lower in polyunsaturated fatty acid than those of the flesh. It is shown that cultured eel contains various nutrients such as protein, minerals, unsaturated fatty acid, so cultured eel can be regarded as a highly nutritious food.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.466-471
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• 2006

We investigated the changes in body weight (BW), plasma sex steroid hormone profiles, and testicular development of cultured male eel Anguilla japonica during an artificial maturation process. Eels that received weekly intraperitoneal injections of eel's ringer solution containing human chronic gonadotropin (HCG) were examined. In the ringer-treated control, BW changes decreased slowly during the experimental period. Plasma testosterone (T), 11-ketotestosterone (11-KT) and $17{\alpha},\;20{\beta}$-dihydroxy-4-pregnen-3-one (DHP) levels In the control remained low and did not show significant changes. Moreover, all germ cells in the testes of the control were spermatogonia. In the HCG-treated male eels, however, BW changes increased gradually from the fifth week and then decreased slowly. The plasma T level increased rapidly (p<0.05) in the second week and then decreased slowly. The plasma 11-KT level increased dramatically (p<0.05) in the second week and was maintained until the end of the experiment. The plasma DHP level increased progressively from the second week and peaked in the eighth week (p<0.05). The testes of HCG-treated male eels were more developed than those of the control; most were at the spermatozoa and spermatid stages and showed active spermiation. Thus, spermatogenesis and spermiation in the cultured eel can be induced by repeated injections of HCG.

• Development and Reproduction
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• v.13 no.1
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• pp.35-41
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• 2009

In the present study, we investigated the effects of rearing condition during the winter period on artificial maturation and reproduction of cultured female eel, Anguilla japonica. The female eel was adapted by combination of environmental conditions (seawater/low temperature, $10^{\circ}C$; seawater/high temperature, $20^{\circ}C$; freshwater/low temperature, $10^{\circ}C$; freshwater/high temperature, $20^{\circ}C$) during 8 weeks of the winter period. Then, the female eel cultivated by different conditions during the winter were transferred to seawater at $20^{\circ}C$ for induction of artificial maturation by salmon pituitary extraction (SPE) injection. The results shown that gonadosomatic index (GSI) and plasma levels of estradiol-$17{\beta}$ (E2) were significantly higher in female eel were reared in seawater than in freshwater, and were the highest at eel adapted by seawater/low temperature. Also, reproduction coefficient were higher in seawater/low temperature than in the other groups. These results will provide valuable information for elevation of the artificial maturation and reproduction coefficient in the cultured female eel.

• Journal of Food Hygiene and Safety
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• v.20 no.2
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• pp.89-97
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• 2005

The influence of different storage temperature and packaging methods on the flying cultured eel bone were investigated. The acid values, peroxide values and fatty acid composition were measured during storage 20$^{\circ}C\;and\;40^{\circ}C$ for 60 days. The lipid oxidation was rapidly progressed with the increased temperature. The addition of oxygen absorber remarkably repressed lipid oxidation during storage of the living cultured eel bone at $20^{\circ}C\;and\;40^{\circ}C$, followed by $N_{2},\;BHA,\;\alpha$-tocopherol and control. The monounsaturated fatty acid content was the highest in the frying cultured eel bone, followed by saturated fatty acid and polyunsaturated fatty acid. The major fatty acids were oleic acid, palmitic acid and linoleic acid. The saturated fatty acids increased with the rise of storage temperature and prolonging the storage period, while monounsaturated fatty acid and polyunsaturated fatty acid were decreased. The changes of fatty acid composition were the lowest in sample by packing with oxygen absorber, followed by packing $N_{2},\;BHA,\;\alpha$-tocopherol and control. from the result of sensory evaluation, sample by packing with oxygen absorber were rated as higher quality than the others.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1058-1067
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• 2000

In this study, eel, puffer and snake head fish, which are widely taken and highly valued for processing into baked fish, soup or fish juice were studied by classifying them into wild fish and cultured fish, and evaluated in terms of taste. The samples were gathered in the area including Kimhae, Samchonpo and Haman in Kyungsangnam-do, Kangsu-Gu in Pusan and Bukcheju-Gun in Cheju-do. Proximate compositions, the content of nucleotides and their related compounds, total and free amino acids, organic acids and fatty acids of the fishes were analysed. Generally, as for the compositions, wild fish had a higher crude fat content and a lower moisture content as compared with cultured fish, while there was no great difference between them in terms of crude protein and ash contents. Nucleotides and their related compounds including ATP, ADP, AMP, IMP, HxR, Hx were detected, and the amounts of which were nearly the same with respect to the growth conditions. IMP content was high in all of the samples, while ATP content was extremely low. Total 17 amino acids were detected from the samples, and most of the samples had high contents of glutamic acid, aspartic acid, lysine, leucine, glycine, alanine and arginine, and low contents of cystein, isoleucine and methionine. As for the other amino acids, generally same level of contents were detected for each samples. In cases of eel and snake head fish, the wild fish had higher total amino acid contents in comparison with cultured fish. And the result to the contrary was obtained for the case of puffer. Sample fishes had nearly the same compose distribution of free amino acid though the contents of which were a little different according to the samples. Each sample had high contents of taurine, hydroxyproline, glutamic acid, glycine, cystathionine, ${\beta}-aminoisobutyric$ acid and lysine. Total organic acid contents of cultured fish was higher than that of wild fish. All fishes commonly had high contents of lactic acid, iso-valeric acid, oxalic acid and fumaric acid. High levels of $C_{16:0},\;C_{16:1},\;C_{18:1(cis)},\;C_{18:3},\;and\;C_{22:6}$ were shown in all of the samples and ${\omega}-3$ polyunsaturated fatty acid content of cultured fish was higher than that of wild fish, and as for the essential fatty acid, wild fish has higher content in comparison with cultured fish.