• Fisheries and Aquatic Sciences
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• v.6 no.2
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• pp.81-87
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• 2003

Experiments were carried out to investigate the accumulation and the histopathological changes in liver of juvenile rockfish, S. schlegeli, after sub-chronic dietary Cu (0, 50, 125, 250 and 500mg/kg) exposure for 60 days. Cu accumulation in liver was significantly increased with dietary exposure period and concentration for 60 days, and has a linear relation with dietary exposure days. After 60 days of Cu dietary exposure, the Cu concentration in the liver was $75.9\pm12.05,\;126.29\pm22.11\;and\;360.44\pm45.26\;{\mu}g/g$ dry weight and was approximately 11-fold, 18-fold and 51-fold higher than in the control diet group at 125, 250 and 500 mg/kg Cu diet group. The accumulation factors were increased with the dietary exposure period in liver of rockfish. In the primary exposed stage, the effect of hepatic tissue in the rockfish exposed to dietary Cu observed enlargement of hepatocytes nuclei, activity of hepatic cells and the swelling of hepatic cells. While exposed time and concentration were increased, the distinct granulation, irregular shape and necrosis of hepatic cells were observed. It was observed that granule degeneration and necrosis showed a part of cells in hepatic tissue after 60 days at 500 mg/kg.

• Journal of fish pathology
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• v.20 no.2
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• pp.99-108
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• 2007

Vibrio harveyi, one of the major causal agent of vibriosis, affects a diverse range of marine vertebrates and invertebrates over a wide geographical area. The organism is synonymous with Vibrio carchariae, which is also known as a fish pathogen. The aims of this study were to investigate the characteristics of the pathogenic non-luminous V. harveyi and the luminous V. harveyi. And V. harveyi isolates were examined the pathogenicity to the black rockfish, Sebastes schlegeli. Both strains of V. harveyi showed haemolytic activity, and the survival rate of non-luminous V. harveyi FR 2 was higher than other strains in the skin, gut mucus and fresh serum of olive flounder, Paralichthys olivaceus and black rockfish, Sebastes schlegeli, respectively. The virulence of non-luminous V. harveyi FR 2 was higher than that of luminous V. harveyi VIB 391 in the intraperitoneally infected black rockfish. In conclusion, the present study revealed that the pathogenicity of V. harveyi FR 2 isolated from marine fish was higher than that of V. harveyi VIB 391 isolated from shrimp for black rockfish. It was suggested that the pathogenicity of V. harveyi on the black rockfish was related with bacterial luminescense.

• Journal of Aquaculture
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• v.14 no.3
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• pp.173-180
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• 2001

Regulation of copulation and parturition of black rockfish, Sebastes schlegeli were induced by artificially controlled photoperiod and temperature. for the treated group, daylength of copulation and parturition period was maintained at 9L : 15D and 14L : l0D, respectively. Temperature was maintained at 12~13$^{\circ}C$ during the copulation period, and at 14~15$^{\circ}C$ during the parturition period. Gonadosomatic index (GSI) of male was low 0.12 from January to August and peak to 1.36~0.10 during November in the control group but 1.27 ~ 0.05 during October in treated group. GSI of female was about 1.82 from January to November 1996 and reached the maximum of 46.5 ~ 5.72 during April 1997 in the control group but 42.0~4.24 during february 1997 in the treated group. The pattern of ovary and testis development did not much differ between the treated and control groups. However, the copulation and parturition of black rockfish could be advance 2~3 months by controlling photoperiod and temperature.

• Journal of fish pathology
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• v.22 no.1
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• pp.9-14
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• 2009

Fifteen diseased rockfish (Sebastes schlegeli) were collected from 4 net-cage farms in Huksan island. Some round transparent nodules were observed on gill filaments in fish. Bacteriological and histopathological examinations on the diseased fish were performed. Any pathogenic bacteria could not be isolated from the internal tissues and histopathological alterations were not found in any of the tissues except the gills. Rock fish were infected with epitheliocystis, Microcotyle sebastes and unknown aetiology on the gills. Cysts of epitheliocystis measuring 44.1-68.9 $\mu{m}$ in diameter were mainly found in the distal portion of the gill filaments and sometimes in the middle portion. But host responses were moderate in spite of formation of the epithelial cysts. Some Microcotyle sebastes captured the secondary filaments with clamps on the opisthohaptor. Attachment of the parasites provoked epithelial proliferation and resulted in gill lamellar fusion.Cysts of unknown origins measuring 26-425 $\mu{m}$ in diameter were found in the cartilage of gill filaments. These cysts contained eosinophilic materials and proliferation of cartilage cells was confirmed around the cysts. But there was no significant pathological changes associated with the presence of the cysts except enlargement of the gill filament with the cysts.

• Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.6-15
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• 2009

Biochemical and functional properties of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from rockfish skin were characterized. Yield of PSC (90.0%) was higher than that of ASC (63.2%). Both ASC and the PSC consisted of ${\alpha}1$ and ${\alpha}2$ chains, and $\alpha$-cross-linked components. According to the results of hydroxylation of proline and lysine, and FT-IR, no difference between the helical structure of ASC and PSC was identified. Thermal denaturation temperature (TDT) of ASC from rockfish skin was $22.8^{\circ}C$, the same as exhibited in PSC. Both ASC and PSC were higher in water absorption capacity (WAC) and oil absorption capacity (OAC) than other vegetable proteins. According to the results of emulsifying activity (EA) and cooking stability (CS), both ASC and PSC from rockfish skin were inferior compared to the commercial emulsifier (Tween-80). The results of FT-IR suggested that the structure of PSC was slightly different when compared to that of ASC. No differences in solubility were established between ASC and PSC from rockfish skin at various pH and NaCl concentrations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.44-50
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• 1996

Sex differentiation in the rockfish, Sebastes schlegeli, was studied by using a histological method for the appearance of primordial germ cell, formation of primitive gonad and differentiation of female and male. The primordial germ cells were buried under fibrous mesenchymal tissue between gut and mesonephric duct of pre-larva with a total length (TL) of 6.3 mm at 2 days after parturition. In juvenile of TL $5.2\~5.9cm$ at 65 days after parturition, the gonad composed of a large number of genial cell and formed of cavity along the lateral side of the gonad, differentiated to the ovary. At this time, the gonad formed seminiferous tubules by somatic cells, differentiated to the testis. In juvenile of TL $7.0\~7.2cm$ cm at 115 days after parturition, gonads divided into testis contained pigment cell and ovary absent pigment cell. S. schlegeli differentiated directly into male or female without an intermediate female phase at early indifferentiated stage. Therefore, S. schlegeli belongs to the differentiated type of gonochoristic teleosts. At 350 days after parturition, sex ratio was approximately 1 : 1(p>0.05).

• Proceedings of the Korean Aquaculture Society Conference
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• 2001.12a
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• pp.280-281
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• 2001

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.12a
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• pp.103-103
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• 2004

• Journal of fish pathology
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• v.34 no.2
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• pp.261-269
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• 2021

This study presents the evaluation of sample extraction and purification procedure for the determination of residues of febantel and its metabolites, fenbendazole, oxfendazole and oxfendazole sulfone in rockfish (Sebastes schlegeli) muscle using liquid chromatography-tandem mass spectrometry. Residues of febantel and its metabolites in rockfish muscle were analyzed using each different sample preparation method from Korean Food Standards Codex (KFSC), Food Safety and Inspection Service (FSIS, USA), and the modified FSIS method using QuEChERS kit (FSIS-Q), respectively. Each method was compared for mean recoveries and repeatabilities. Since FSIS-Q showed higher repeatabilities (coefficient of variation, CV of 2.4%~10.9%) than those of FSIS method (CV of 4.6%~17.5%), recoveries from FSIS-Q were compared with those from KFSC method. FSIS-Q showed significantly higher recoveries of 83.1%~110.1% (P < 0.05) than those from KFSC method of 64.7%~107.4%. In addition, FSIS-Q showed a good linearity over the range of 2.5~200 ㎍/kg, and excellent sensitivities with limit of detection of 0.46~0.71 ㎍/kg and limit of quantification of 1.08~2.15 ㎍/kg. Although all the sample preparation methods turned out to be able to meet CODEX guideline for all the compounds, FSIS method and FSIS-Q validated in this study could be applied to screening and quantification for residues of febantel and its metabolites in rockfish muscle with efficient preparation procedures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.721-726
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• 1998

The changes of thyroid hormone levels in plasma, eggs and yolk-sac larvae in female rockfish (Sebastes schiegeli) were examined after maternal injection of 3,5,3'-triiodo-L-thyronine ($T_3$) with a dose of 20 mg/kg fish wt. There were no differences of L-thyronine ($T_4$) level in maternal plasma and yolk-sac larvae between $T_3$ injection and vehicle-injected control. The significant decrease of $T_4$ level was found in eggs from the $T_3$ injected mother fish compared with that of control. $T_3$ levels in maternal plasma, eggs, and yolk-sac larvae were significantly elevated by $T_3$ injection. Therefore $T_4$ and $T_3$ in maternal circulation may be transferred into oocytes and subsequently into the yolk-sac larvae. These findings suggest that thyroid hormones may play some roles on physiological metabolism during early larval development of rockfish.