• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.390-398
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• 2015

A feeding experiment was conducted to determine the use of distillers dried grain (DDG) as a partial replacement for fish meal in the diet for juvenile rockfish, Sebastes schlegeli. Four iso-nitrogenous (50% crude protein) and iso-caloric (4.3 kcal/g) diets (designated as DDG0, DDG7, DDG14, and DDG21) were formulated to contain 0, 7, 14, and 21% DDG. Triplicate groups of juvenile rockfish (initial body weight, $10.2{\pm}0.2g$) were fed one of the experimental diets to visual satiety twice a day (09:00 and 17:00) for 8 weeks. At the end of the feeding trial, survival of rockfish was above 97% and not affected by dietary DDG levels (P>0.05). Weight gain, feed efficiency and daily feed intake of juvenile rockfish were significantly decreased with increase of dietary DDG levels (P<0.05). Condition factor, hepatosomatic index and visceralsomatic index of juvenile rockfish were not significantly affected by dietary DDG levels (P>0.05). No significant differences were observed in the contents of moisture, crude protein, crude lipid and ash of the whole body and dorsal muscle in juvenile rockfish fed the experimental diets (P>0.05). Therefore dietary inclusion of DDG as a replacement for fish meal could depress the growth of juvenile rockfish.

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.359-369
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• 2001

Polymerase chain reaction (PCR) amplification of DNA as 30 different arbitrary primers and random amplified polymorphic DNAs (RAPD) analysis were performed on genomic DNA extracted from the blood of the marine rockfish (Sebastes schlegeli) from the Yellow Sea and the Southern Sea. The unique properties of the genomic DNA were used to investigate the features of the population dynamics and origins of the species. Out of 30 primers, seven generated 207 highly reproducible RAPD polymorphic products, producing approximately 2.7 polymorphic bands per primer. About 67.4% of total amplified products (307) were either polymorphic (207) to rockfish. The degree of similarity varied from 0.22 to 0.63 as calculated by bandsharing analysis. Also, the average level of bandsharing was 0.39$\pm$0.02 within the rockfish strains. The electrophoretic analysis of RAPD-PCR products showed the relatively high levels if variation between different individuals in rockfish from the Yellow Sea. However, the RAPD outlines obtained with DNA of different rockfish strains from the Yellow Sea and the Southern Sea in Korea were very similar. Also, a small number of polymorphic bands were identified. Even if further analyses or more rockfish populations are required, this result implies RAPD analysis reflects genetic differences between the geographical strains of the rockfish.

• Journal of fish pathology
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• v.18 no.3
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• pp.293-300
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• 2005

This study was conducted to investigate the effect of bisphenol A (BPA; 4,4' -isopropylidenediphenol) on haematological parameters of Korean rockfish, Sebastes schlegeli in laboratory condition, Fish were randomly distributed into three treatment groups which were received of 0.1, 1 and 10 mg BPA $kg^{-1}$ body weight. They were injected four times intraperitoneally at days 0,3,7 and 12 with BPA. Control group was subjected to the same regime using an equal volume of 60% ethanol-mixed PBS carrier injection only. Fish from each group were sacrificed on day 15 after first injection for haematological assay. Observations on haematological parameters indicated BPA-treatment induced lower level of red blood cell counts and hemoglobin concentration. Serum chloride, calcium, glucose, bilirubin and blood urea nitrogen concentrations increased following exposure to BPA at 10 mg $kg^{-1}$ body weight. In contrast, serum cholesterol in fish exposed to BPA decreased. Serum transaminase and lactate dehydrogenase activities after the highest level of 10 mg $kg^{-1}$ PBA was significantly increased. These results demonstrate that BPA have induced adverse impact on haematological parameters in the Korean rockfish, Sebastes schlegeli.

• Journal of Life Science
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• v.10 no.6
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• pp.548-557
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• 2000

A eight weeks feeding experiment was conducted to investigate the effects of different dietary dimethyl-$\beta$-propiothetin (DMPT) levels on growth and chemical components in Korean rockfish (Sebastes schlegeli). The content of DMPT extracted from Enteromorpha intestinalis by autoclaving was 31.1 mg%. Body weight gain and feed efficiency were significantly increased with dietary DMPT level. After eight weeks of feeding trial, moisture content decreased with supplemented DMPT level, while crude protein and lipid contents increased with dietary DMPT level. Amino acid contents of muscle was elevated in the DMPT added groups compared to control group. Amino acid composition of muscle in fish fed the diets supplemented DMPT was not different to that of control group. Fatty acid contents of muscle in fish increased with dietary DMPT level.

• Journal of fish pathology
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• v.11 no.1
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• pp.83-86
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• 1998

The benedeniine monogenean Benedenia derzhabini (Layman, 1930) Meserve, 1938 from cultured Korean rockfish, Sebastes schlegeli, is described and reported for the first time in Korea. The parasite was recovered from the gills and inner wall of operculum. B. derzhavini is distinguished from B. seriolae and B. sebastodis by the relative shape and length between the accessory sclerites and the hamuli.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.2
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• pp.84-94
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• 2007

The comparative feeding ecology of greenling Hexagrammos otakii and Schlegel's black rockfish Sebastes schlereli populations was investigated in the Jangbong tidal flat near Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. The stomach contents of 124 greenling and 115 Schlegel's black rockfish were analyzed. The diet of H. otakii was dominated by the amphipods Gammaropsis iaponicus, Caprella scaura, Isaeopsis sp. and Monocorophium acherusicum, the shrimps Latreutes mucronatus and Alpheus japonicus, the mysid Neomysis orientalis and the bivalve Mytilus edulis. In contrast, S. schlegeli mainly fed on the mysids N. orientalis, N japonica, and N. awatschensis, the shrimps Exopalaemon carinicauda, A. japonicus and L. mucronatus, and the fish Pholis fangi and unidentified gobiids. A comparison of the frequency and abundance of food items showed that crustaceans (e.g. amphipods, mysids and shrimps) were important foods for both species. Their main dietary components, however differed which is probably due to differences in the spatial distribution of the two species and their prey items. In conclusion, greenling and Schlegel's black rockfish, despite being sympatric on a tidal flat have distinct food habits and low dietary overlap (Schooner's index: 0.1). These results indicate, to some extent, resource partitioning for the maximum utilization of available foods in the tidal flat.

• Fisheries and Aquatic Sciences
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• v.21 no.8
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• pp.29.1-29.8
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• 2018

This study was conducted to evaluate the use of tuna by-product meal (TBM) as a substitute for fishmeal in juvenile Korean rockfish (Sebastes schlegeli) diets. Five isonitrogenous (52% crude protein) and isocaloric (4.9 kcal/g) diets were prepared. Control diet (Con) was formulated to contain brown fishmeal, whereas 25, 50, 75, and 100% of fishmeal was substituted with the same percentage of TBM in the TBM25, TBM50, TBM75, and TBM100 diets, respectively. Three replicate groups of fish (initial weight, $29.5{\pm}0.6g$) were fed one of the five diets for 12 weeks. The mean weight gain of fish fed the Con and TBM25 diets was significantly higher than that of fish fed the TBM100 diet (P < 0.05), but it was not significantly different from the weight gain of fish fed the TBM50 and TBM75 diets. The feed efficiency and protein efficiency ratios of fish fed the Con diet were significantly higher than those of fish fed the TBM100 diet (P < 0.05), but were not significantly different from those fed the TBM25, TBM50, and TBM75 diets. The TBM25, TBM50, TBM75, and TBM100 diets had significantly (P < 0.05) lower incidence cost and higher profit index than the Con diet. These results suggest that the tuna by-product meal used in this study could replace up to 75% of fishmeal protein in the diet without reducing growth and feed utilization in juvenile Korean rockfish weighing 29-53 g. By considering feed cost, the TBM 75 diet is recommendable for Korean rockfish farming.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.180-186
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• 1998

A 10-week feeding experiment was conducted to determine the phosphorus requirement of juvenile Korean rockfish (Sebastes schlegeli). Three replicate groups of fish initially averaging 4.2g were fed the semipurified experimental diets containing graded levels of $NaH_2PO_4\;\cdot\;2H_2O$ to provide from $0.1\%$ to $1.32\%$ total phosphorus level in a flow-through seawater system. Korean rockfish muscle and casein were used as the protein sources of the basal diet. Weight gain, feed efficiency and protein retention of fish fed the $0.35\%$ phosphorus were higher than those of fish fed the $0.1\%$ phosphorus, although no significant improvements $(P>0.01)$ were observed above the level. Determined phosphorus requirement using the broken line model was found to be $0.3\%$ for weight gain. Moisture, protein and lipid contents of whole body and muscle were not affected by dietary phosphorus levels $(P>0.01)$. Lipid contents of liver in fish fed the $0.1\%$ phosphorus were lower than those in fish fed the $0.35\%$ and $1.32\%$ phosphorus $(P<0.01)$. Dietary phosphorus increased ash and phosphorus contents of the whole body, while those of bone were not affected $(P>0.01)$. The data obtained in this study indicate that a $0.3\%$ dietaryphosphorus level could be recommended for the optimum growth and efficient nutrient utilization of juvenile Korean rockfish.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.35-43
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• 2007

Age and growth of black rockfish, Sebastes schlegeli sampled from the Tongyeong marine ranching area in Korea waters were determined from 1,173 otoliths from July, 2001 to May, 2004. Examination of outer margins of the otolith showed that the opaque zone was formed once a year. Marginal increment of the otolith formed annual ring from July. The von Bertalanffy growth curve had the growth parameters estimated from non-linear regression were $L_t=48.45(1-e^{-0.2139(t+0.4313)})$, $W_t=1,837.93(1-e^{-0.2139(t+0.4313)})^{3.02}$ 3.02 for females and, $L_t=49.32(1-e^{-0.1775(t+0.7403)})$, $W_t=1,887.83(1-e^{-0.1775(t+0.7403)})^3$ for males, where t is age (year) and Lt is body length (mm) at age t. Growth at the age of male and female shows significant difference (p<0.01).

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.387-393
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• 2004

Experiments were carried out to investigate the lipid peroxidation (LPO), superoxide dismutase (SOD) activity and histopathological change of hepatic tissue for rockfish, Sebastes schlegeli after feeding sub-chronic dietary Benzo(a)pyrene (BaP) in the concentration of 0 (control), 0.5, 1.0, 1.5, 2.0 mg $kg^{-1}$ dry food of diet for 30 days. In 2.0 mg $kg^{-1}$ dry food group, the significant increase of LPO was observed in all period, and SOD activity was incresed at 30 days significantly in the same concentration. In the histological investigation of liver, there was the swelling of hepatic cells at 10 days over the 1.0 mg $kg^{-1}$ dry food concentration. At 30 days Periodic acid-Schiff (PAS) positive granule was observed in the same group and at 20 days was observed in 2.0 mg $kg^{-1}$ dry food group. And there was necrosis of hepatic cell in some fish of 2.0 mg $kg^{-1}$ dry food group at 30 days.