• Fisheries and Aquatic Sciences
• /
• v.5 no.4
• /
• pp.308-310
• /
• 2002

Effect of 4-nonylphenol (4-NP), endocrine disrupting compounds (EDCs), on glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) were investigated in the plasma of juvenile rockfish, Sebastes schlegeli. Fish were injected with 4­NP (10, 50, 100 and 200 mg/kg body weight) in $70\%$ ethanol twice at 3-day intervals and plasma sampling were extracted at 7 days after the last injection. Controls received solvent only. 4-NP significant increased GOT in a dose-dependent manner. GPT was markedly elevated to $61\%$ (P<0.05) and $82\%$ (P<0.01) than that of the control at the 4-NP doses of 100 and 200mg, respectively. These results suggest that the estrogenic activity of 4-NP increase plasma GOT and GPT by toxic effect on hepatocyte.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.11
• /
• pp.1615-1622
• /
• 2011

A factorial ($4{\times}2{\times}2$) experimental design was employed to determine apparent digestibilities of dry matter (DM), protein, lipid, energy and nitrogen-free extract (NFE) of the test diets containing either ${\alpha}$-potato starch (A-PS), ${\beta}$-potato starch (B-PS), ${\beta}$-corn starch (B-CS) or dextrin (DEX) as dietary carbohydrate energy for juvenile (average weight 30 g) and grower (average weight 300 g) rockfish reared at 13$^{\circ}C$ and 20$^{\circ}C$. Chromic oxide was used as an inert marker. Feces were collected by fecal collectors attached to rearing tanks from triplicate groups of juvenile and grower rockfish. Digestibilities of DM, energy and NFE of the test diets were significantly affected by dietary carbohydrate and water temperature (p<0.01), but not by fish size. DM digestibility of the fish fed the A-PS diet was significantly higher than that of fish fed other treatments, except for the DEX diet at 20$^{\circ}C$. DM digestibility of rockfish fed the B-CS diet was significantly lower than that of other diets. A similar pattern was observed in apparent digestibility of energy. NFE digestibility of fish fed the test diets was significantly affected by carbohydrate and significantly correlated to DM (r = 0.97, p<0.01) and energy (r = 0.99, p<0.01) digestibilities, regardless of water temperature and fish size. NFE digestibility of the fish fed the ${\beta}$-starch diets was relatively lower compared to that of the ${\alpha}$-starch diets, and ranged from 35 to 43% and 20 to 27% for B-PS and B-CS, respectively. The present findings indicate that carbohydrate and water temperature significantly affected digestibilities of dry matter, energy and nitrogen-free extract of rockfish. Among dietary carbohydrates, ${\alpha}$-potato starch could be effectively used as dietary carbohydrate energy for rockfish at 13$^{\circ}C$ and 20$^{\circ}C$.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.1
• /
• pp.102-110
• /
• 2015

The characteristics of aquatic light fields are generally reflected in the visual systems of fishes inhabiting them. Therefore, research on light sensitivity of fish is useful to explain the correlation between the visual function and habitat, behavior and distribution of fish. Rockfish is an important species in coastal ecology and also one of the main species for culturing in Korea. To make a contribution on the maintenance of the fish resources and understanding the ecology of the rockfish, the visual spectral sensitivities of the dark-adapted rockfishes were measured in the range of visible light (405~660 nm) using a light source of light-emitting diodes (LEDs). In order to assess electrophysiological response of the fish, the ERGs (electroretinograms) of the dark-adapted rockfishes were recorded on a data logger (12 bits) and a laptop computer. Juvenile (n=5; weight: $20.3{\pm}5.2g$; total length: $10.3{\pm}0.7cm$) and adult (n=5; weight: $87.8{\pm}21.8g$; total length: $18.1{\pm}1.3cm$) rockfishes were used in experiment. The visual threshold of juvenile and adult rockfish were 11.66 (log quanta/$cm^2/s$) and 11.81 (log quanta/$cm^2/s$) in 574 nm, respectively. The peak wavelength of the spectral sensitivity in the dark-adapted juvenile and adult rockfish was commonly 551 nm (series of green color). Collectively, these results demonstrate that the rockfish has suitable visual capabilities for inhabiting coastal water in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.55 no.3
• /
• pp.319-327
• /
• 2022

An eight-week feeding trial was conducted to evaluate the effects of a diet consisting of different onion juice processing by-product (OJPB) levels on juvenile black rockfish Sebastes schlegelii growth, feed utilization, and, lysozyme and antioxidant enzymes activities. Juvenile rockfish (2.2 g) were randomly distributed into 15 flow-through tanks (30 fish/tank). Five experimental diets were prepared in triplicate. The experimental diets were supplemented with OJPB at different levels of 0 (control), 0.25, 0.5, 0.75 and 1% (designated as OJPB0, OJPB0.25, OJPB0.5, OJPB0.75 and OJPB1, respectively). At the end of the feeding trial, the results revealed that the fish that were fed the OJPB0.75 and OJPB1 diets showed enhancement in growth (weight gain and specific growth rate) and feed utilization (feed efficiency and protein efficiency ratio) compared with the fish that were fed other diets. Plasma lysozyme, glutathione concentration, and superoxide dismutase and catalase activities significantly increased in the fish that were fed the OJPB0.75 and OJPB1 diets. In conclusion, dietary supplementation of 0.75-1% OJPB in juvenile rockfish diet improved the growth performance and antioxidant status.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.5
• /
• pp.546-551
• /
• 2013

This study examined the effects of the dietary inclusion of Porphyra and sea tangle Laminaria japonica on the growth, feed utilization, body composition, and plasma chemistry of juvenile Korean rockfish Sebastes schlegeli. Eight hundred and forty juvenile fish averaging 5.0 g were allocated 40 fish per tank to 21 180-L flow-through tanks. Seven experimental diets were prepared: control (Con) without additive, 0.5 and 1% Porphyra extract (PE), 3% Porphyra powder (PP), 0.5 and 1% sea tangle extract (STE) and 3% sea tangle powder (STP), referred to as PE-0.5, PE-1, PP-3, STE-0.5, STE-1, and STP-3, respectively. Each additive was included in the experimental diet at the expense of the same amount of wheat flour. Each experimental diet was fed to triplicate groups of fish. The experimental diets had no effect on the survival, weight gain or specific growth rate of the fish, feed consumption, feed efficiency ratio, protein efficiency ratio, protein retention, hepatosomatic index, condition factor, moisture or crude protein content of the entire body excluding the liver or moisture, crude protein or crude lipid content of the liver. None of the plasma parameters were affected by the experimental diets. Based on these results, the dietary inclusion of Porphyra and sea tangle did not affect the growth, feed utilization, body composition or plasma chemistry of juvenile Korean rockfish.

• Journal of Fisheries and Marine Sciences Education
• /
• v.26 no.4
• /
• pp.695-704
• /
• 2014

The purpose of this study was to obtain reference values of serum chemistry in Korean rockfish (Sebastes schlegeli), 5 juvenile (n=25) and 3 broodstock (n=15) subpopulations which were differentiated by cultured method. Serum samples were analyzed for the following commercial clinical kits: total protein, albumin, glucose, AST (aspartate aminotransferase), ALT (alanine aminotransferase), total cholesterol, free cholesterol, LDH (lactate dehydrogenase) and ALP (alkaline phosphatase). Significant differences were observed in the values of total protein, albumin, total cholesterol, AST, ALT, LDH and ALP between juvenile and broodstock subpopulations. In the comparison of total protein, albumin, total cholesterol and ALP, broodstock subpopulations showed higher levels. On the other hand, increased AST, ALT and LDH were observed in juvenile subpopulations. These results indicate that cultured method are major contributors to health-related physiology of Korean rockfish, juveniles and broodstocks.

• Journal of Fisheries and Marine Sciences Education
• /
• v.24 no.5
• /
• pp.609-615
• /
• 2012

A histo-pathogical examination was carried out to evaluate the effect of commercial extruded pellet (EP) and a raw fish moist pellet (MP) diet on the health of juvenile rockfish cultured in marine net-cage for 7 months. Fish were distributed randomly to each net cage as a group of 76,000 fish (initial mean body weight 5.9 g). After 2 months, the hypertrophy or swelling of liver parenchymal cells was identified in most individuals and lasted until 7 months. Livers in EP fed group frequently showed hypertrophic parenchyma and fatty change with occasional atrophic cells. However, after 4 months, lymphocytic infiltration in splenic parenchyma was seen in a number of individuals. In addition, the gastric glandular epithelium was atrophied and in the lumen of renal tubules protozoan parasites were frequently identified but there was no correlation with the type of feed. Moreover, juvenile rockfish on EP diet showed gross and microscopic hypertrophy of the liver which would be due to oversupply of feed. Severe hepatic cellular hypertrophy or swelling could lead to the damage of microcirculation. Especially fatty change and atrophic change of liver could be the result from the damage, which could be responsible for immunological problem. Lymphocytic infiltration of spleen on the MP diet suggests that juvenile rockfish could be frequently exposed to infectious antigens.

• Fisheries and Aquatic Sciences
• /
• v.21 no.8
• /
• pp.29.1-29.8
• /
• 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
• /
• v.1 no.2
• /
• pp.180-186
• /
• 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.

• Environmental Analysis Health and Toxicology
• /
• v.17 no.3
• /
• pp.239-243
• /
• 2002

Changes of plasma vitellogenin (VTG) and glutamate pyruvate transaminase (GPT) were examined for determining whether hepatocyte was damaged during the process of VTG induction in the juvenile rockfish, Sebastes schlegeli exposed to exogenous estrogen (estradiol-l7$\beta$, E$_2$). Rockfishes were intraperitoneally injected with E$_2$(5 mg/kg B.W.) in 70% ethanol and plasma sampling were extracted at 0, 1, 3, 6, 9, 12, 15 days af-ter E$_2$administration. VTG and GPT were then analyzed by SDS -PAGE and Reitman -Frankel method, respectively. VTG band was detected at a molecular weight position of 175 kDa on Day 3 after E$_2$administration. This band became more distinct at 6 days, but its was gradually thinned with time -course, and not detected at 15 days. GPT was suddenly increased at 1 days after 22 administration and highest GPT was detected at 3 days. However. GPT was gradually decreased with time -course as the change of VTG. These results suggest that the process of VTG induction by exogenous E$_2$damage to hepatocyte, and plasma GPT was temporarily increased in the juvenile rockfish.