• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.580-581
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• 2006

• Journal of fish pathology
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• v.26 no.1
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• pp.1-9
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• 2013

The acute toxicity and sublethal effects of nitrite on the dark-banded rockfish, Sebastes inermis (mean body weight: $83.3{\pm}7.2$ g), were studied under static conditions for a period of 96 h. The acute toxicity of nitrite was at the 50% lethal concentration ($LC_{50}$) of 700 mg/L. The sublethal effects on selected hematological parameters of the dark-banded rockfish, such as its osmolality, hematocrit, cortisol, alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were measured after 0, 6, 12, 24, 48, 72, and 96 h of exposure to 0, 50, 100, 200, 400, or 700 mg/L nitrite. Sublethal nitrite caused a progressive reduction in the hematocrit of the fish, depending on the nitrite concentration and the exposure period. Exposure to 100-700 mg/L nitrite for 96 h caused a reduction in the hematocrit and an increase in cortisol, ALT, and AST compared with the control levels. Abnormal ultrastructural changes in the gills and liver tissues were observed in fish exposed to 700 mg/L nitrite for up to 96 h compared with the control tissues. Ultrastructural changes included atrophic gill mitochondria and hepatocytes that developed smooth endoplasmic reticulum and atrophic mitochondria. Although no rockfish mortality occurred at 500 mg/L nitrite, all the hematological parameters examined responded adversely to a nitrite dose of 200 mg/L for 96 h. These results show that although the acute toxic concentration of nitrite for the dark-banded rockfish is > 700 mg/L, sublethal concentrations of nitrite also negatively affect its hematological parameters.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.118-126
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• 2010

A feeding trial was conducted to investigate the effects of different levels of dietary n-3 highly unsaturated fatty acids (HUFA) (1.1-5.6%) and vitamin E (70 and 400 mg/kg) on the growth and body composition of juvenile rockfish. Six isonitrogenous (45% crude protein) and isolipidic (17% crude lipid) diets were formulated to contain graded levels of n-3 HUFA and vitamin E. Diets 1, 2 and 3 consist of 400 mg vitamin E/kg diet with graded levels of 1.1, 3.0, and 5.6% n-3 HUFA, respectively. Graded levels of n-3 HUFA (1.1, 3.0, and 4.0%) were added in diets 4, 5 and 6, respectively, containing 70 mg vitamin E/kg diet each. At the end of feeding trial, growth performance of rockfish was affected by neither dietary n-3 HUFA nor vitamin E levels. Feed efficiency and hepatosomatic index were slightly decreased (P<0.05) with increment of dietary n-3 HUFA at each dietary vitamin E level. Dietary vitamin E and n-3 HUFA levels did not affect proximate composition and vitamin E concentration in the dorsal muscle of rockfish. Liver moisture and crude protein contents positively related to dietary n-3 HUFA levels. Liver lipid content and hematocrit value were significantly decreased (P<0.05) by increasing dietary n-3 HUFA levels. Eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA) concentrations in the dorsal muscle significantly correlated to dietary n-3 HUFA levels, except for fish fed the diet 6 containing 4% n-3 HUFA and 70 mg vitamin E/kg diet. EPA concentration in the dorsal muscle of fish fed the diet 6 was significantly lower than that of fish fed the diets 2, 3 and 5. The present findings suggest that feeding of diets containing excessive n-3 HUFA level with varying addition of vitamin E may alter fatty acid composition in the dorsal muscle, but do not affect growth of juvenile rockfish.

• 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 Ichthyology
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• v.32 no.2
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• pp.70-77
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• 2020

A feeding experiment was conducted to investigate the effects of replacement of dietary fish meal by frozen whole krill (FWK) and/or krill meal (KM) on growth performance and body composition of juvenile black rockfish, Sebastes schlegeli. The basal experimental diet (ED) contained 58.4% fish meal (FM) as a control, the other five EDs were formulated with the protein replacement ratio of fish meal by as 0, 10, 20, 30, and 40%, respectively (FWKM0, FWK10, FWK20, FWK20KM10, FWK20KM20 and FWK20KM20HP). Each diet was fed to juvenile rockfish initially weighing 3.09±0.02 g/fish in a flow-through system. The control ED containing 58.4% FM and 10% FWK diet showed significantly higher weight gain and feed efficiency than all the other EDs containing 20, 30, and 40% FWK and/or KM. But the survivals, whole-body moistures, crude proteins and lipids of black rockfish fed all EDs were similar in all EDs. The only whole-body ashes of juvenile black rockfish were significantly differentiated by feeding the various EDs containing different levels of FWK and/or KM with a protein and lipid levels adjustment. These results suggest that dietary frozen whole Antarctic krill and/or krill meal inclusions could not improve the growth but change the whole-body ashes in juvenile black rockfish. Therefore, this study further indicates that dietary more than 20% of FWK and/or KM supplementation could not be a potential source of animal protein to replace fishmeal in juvenile black rockfish.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.63-70
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• 2010

Two feeding experiments were conducted to investigate the effects of dietary genetically modified (GM) soya and com on growth performance, feed utilization and body composition of juvenile olive flounder, Paralichthys olivaceus and rockfish, Sebastes schlegelii. For each fish species, four isonitrogenous (50% crude protein) and isocaloric (4.1 kcal/g) diets (designated as nGM soya, GM soya, nGM com and GM com) were formulated to contain 20% non-GM (nGM) and GM soya and com. Thirty olive flounder (initial body weight, 15.4${\pm}$0.4 g) and fifty rockfish (initial body weight, 3.1${\pm}$0.02 g) were distributed in each 400 L tank (200 L water) in a flow through system. Each experimental diet was fed to triplicate groups of fish to visual satiation, twice a day (9:00 hand 17:00 h) for 6 weeks. Growth performance was measured every three weeks. No effects of GM feedstuffs on survival were observed. Dietary inclusion of GM feedstuffs did not affect growth performance and feed utilization of fishes, except for rockfish fed GM com. Rockfish fed the GM com diet showed higher weight gain, daily feed intake and daily protein intake than did fish fed the nGM com diet, but no significant differences were observed in final body weight between the dietary treatments. Condition factor, hepatosomatic index, visceral somatic index and body composition were not altered by the inclusion of GM feedstuffs. These results indicate that dietary inclusion of GM soya and com could have no effects on growth performance and feed utilization of juvenile flounder and rockfish. Lower weight gain and feed intake in flounder and rockfish fed the diets containing 20% soya were likely due to anti-nutritional factors, rather than transgenic factors in the feedstuffs. Dietary inclusion of GM soya and com at the level tested did not alter the body composition of fishes. Further studies to investigate the effects of GM feedstuffs on health conditions and the development of fishes, as well as those of residue of transgenic fragments in ambient environments and in animals are necessary for safe use of the ingredients in aquaculture.

• Journal of Veterinary Clinics
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• v.23 no.3
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• pp.236-242
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• 2006

Along with olive flounder(Paralichthys olivaceus), black rockfish(Sebastes schlegeli) is another very popular maricultured species in Korea. As there is many difficulties in handlling live fish for aquaculturist, use of suitable anesthesia for proper handling of fish is very important in the field. In this view, the effect of $AQUI-S^{\circledR}$ has analysed for its use in the field. $AQUI-S^{\circledR}$, contains 50% isoeugenol, is a new anesthics for fish and zero-withdraw time required since it was approved as a safe additives of food. In the present study, black rockfish adult exhibted sedation effect from 5 ppm at $10^{\circ}C\;and\;15^{\circ}C$, and 7.5 ppm at $20^{\circ}C$, on the other hand, anesthesia was at least required 7.5 ppm at $10^{\circ}C\;and\;15^{\circ}C$, and 10 ppm at $20^{\circ}C$. The fish was recovered from sedation and anesthesia after approximately 5 and 10 minutes, respectively. In case of black rockfish fry, sedation was recorded from 2.5 ppm at $20^{\circ}C$, and 5 ppm at $15^{\circ}C\;and\;20^{\circ}C$. The least concentraion of anesthesia was 2.5 ppm at $10^{\circ}C$, 7.5 ppm at $15^{\circ}C$, and 5 ppm at $20^{\circ}C$. The acute toxic test showed that black rockfish adult and nv showed mortality above 12.5 and 15 ppm concentration of $AQUI-S^{\circledR}$, respectivly. In sum, $AQUI-S^{\circledR}$ is considered as useful anesthetic drug for sedation and anesthesia of black rockfish, it is highly availbale to be prevented from a varity of stress.

• 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.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.103-113
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• 2006

This study examined effects of crude oil on the phase II drug-metabolizing enzymes UDP-glucuronosyl transferase (UDPGT) and glutathione S-transferase (GST) in mussel Mytilus edulis and rockfish Sebastes schlegeli, a representative bivalve and a culture fish, respectively. This work also intended indirectly to evaluate the post impact recovery from the massive oil tanker spillage accidents occurred during the summer of 1995 in the sea area off Yosu City, Chonnam. For these, enzyme activities of UDPGT and GST were examined in the fish and mussel following laboratory exposure to fresh crude oil, weathered oil, field-obtained oil residues, or in the field biota samples. Decreased GST activity was observed in rock fish following exposure to oil-soluble fraction (OSF) of fresh oil. A similar diminished GST activity was also observed after OSF of artificially weathered oil. OSF of field oil residues retrieved from the spillage area approximately 1 year later also exerted a slight inhibition of GST to rockfish. There was neither a change in UDPGT in rockfish, nor were there changes in mussel in both enzymes to any oil fractions. We could not observe any difference in the two enzymes either in rockfish or mussel sampled from the field during $1.5{\sim}2.0$ years post spillage, indicating that their enzyme systems might had been recovered by the sampling time. In conclusion, it seems that the inhibition of GST activity in rockfish is a biomarker response to crude oil exposure. The results, however, must be interpreted with care, as the inhibition nay reflect various factors such as oil concentration, duration and water temperature.

• Development and Reproduction
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• v.10 no.3
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• pp.177-184
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• 2006

Retinol-binding protein(RBP) plays an important role in the specific transport of retinol to target cells through the blood stream in higher vertebrates. In order to clarify the effects of 4-nonylphenol(4-NP) on RBP mRNA expression in the rockfish, Sebastes schlegeli which is common in coastal waters of Korea and commercially important species, the cDNA library was constructed from the liver, and a partial fragment of the RBP gene was cloned. The deduced amino acid sequence from the RBP mRNA showed a high homology to the amino acid sequence from Sparus aurata(80%), Oncorhynchus mykiss(72%) or Anguilla anguilla(78%). Effects of 4-NP on RBP and vitellogenin(VTG) mRNA expression level in rockfish were examined by the northern blot analysis. In female and male rockfish injected with 4-NP(10 mg/kg BW, lower dose), there was no changes in the levels of VTG mRNA expression in the liver. The RBP mRNA levels, however, decreased at 48 hours after the injection in male. In the rockfish injected with 4-NP(25 mg/kg BW, higher dose), the level of VTG mRNA expression increased after 24 hours, regardless of sex. The level of RBP mRNA expression decreased at 48 hours after the injection in both sexes. These data indicate that estrogenic mimics such as 4-NP exhibit a contrasting effect on RBP and VTG gene expression in rockfish.