• Asian-Australasian Journal of Animal Sciences
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• v.24 no.11
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• pp.1615-1622
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• 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
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• v.51 no.1
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• pp.102-110
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• 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
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• v.47 no.5
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• pp.603-610
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• 2014

We investigated a nematode infection in the epithelial tissue of rockfish Sebastes schlegeli cultured in Cheonsu Bay, western Korea, from May 2013 to April 2014. Nematodes infected the epithelial tissues of various external organs, including the fins, operculum, nares, mouth, and head. Over a 1-year period, the overall nematode infection rate in rockfish was 55% (n=89/163): 56.7% (n=17/30) in May 2013, 88% (n=29/33) in August 2013, 0% (n=0/30) in October 2013, 70% (n=21/30) in January 2014, and 55% (n=22/40) in April 2014. During this study, the only mass mortality of cultured rockfish in Cheonsu Bay was in August 2013, when we identified skin wounds on the rockfish caused by the nematodes escaping from their hosts. During this period, the accumulated mortality for 2 weeks was 1.4-22.4% in different farms. In addition, several pathogenic bacteria (Photobacterium damselae, Vibrio spp., and Streptococcus iniae) were isolated from the moribund rockfish; these were thought to be transmitted through the skin wounds caused by the nematodes.

• The Journal of Fisheries Business Administration
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• v.40 no.3
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• pp.69-88
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• 2009

This research was as part of restocking project conducted until 1986. The necessity of its economic and scientific verification on restocking project increased. The economic analysis of this project was intended to measure its effectiveness of rockfish restocking throughout certain water areas. The rockfish restocking in 2008 was carried two regional governments of Gyeongnam and Busan. 3-year average annualized performance is 3.76 million rockfish restocked and 940 million won invested. As Gyeongnam restocked 3.62 million rockfish and invested 890 million won, most of rockfish stocking accomplished in Gyeongnam. The public shipment was the 3-year average amount was about 400 tons. Each Suhyup shipment as follows; TongYong 66.6 tons, Namhae 23.6 tons, Samcheonpo 17.2 tons; Yeosu 13.3 tons, Geoje 4.7 tons, Goseong 3.1 tons, Hadong 1.0 tons. The private shipment was assessed by the interview of relevant market participations. The high percent areas of public ship were Nemaha, Goseong 90% and Geoje 80% or more. Hadong and Samcheonpo were about 50%. TongYong was 10% and the lowest. The private shipment was calculated using the percentage of private shipment surveyed. The total amount of private shipment was 4.8 billion, where 4.5 billion was TongYong, where most of private shipment is being made. The positive economic benefit occurred when the percent of restocked is over 15% in the overall catch. The percentage of restocked investigated with genetic test was 58.2%. With 58.2% ratio of restocked, there was 3.8 times economic benefit according to approximately 3.6 billion won. Economic effects were highly significant. As catch increased according restocking, joint market commission increased. Joint market commission was calculated as total restocked shipment multiplied by the ratio of commission, the calculated commissions were as follows; Hadong 5.0%, Geoje 4.8%, Goseong 4.8%, Namhae 4.8%, Samcheonpo 4.3%, Yeosu 4.3%, TongYong 4.0%. According to calculation results, annual commission fee of ￦60,000,000 was raised during 2006~2008. The fishing catch bulk for entertainment significantly increased in sea area carried with mass restock.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.119-125
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• 2006

To understand the comprehensive mechanisms of biological function for insulin-like growth factor-I (IGF-I) in vertebrates, we have investigated the cDNA sequence of this gene in the korean rockfish (Sebastes schlegeli). The mature form of korean rockfish IGF-I was found to be comprised of 67 amino acid residues, showing about a 7 kDa molecular weight. In this study, we used the polymerase chain reaction (PCR) to obtain a korean rockfish IGF-I (KR IGF-I) cDNA fragment, and methods of rapid amplification of cDNA ends (RACE) to obtain a full length of the KR IGF-I sequence. The KR IGF-I encoded for a predicted amino acid sequence showed identities of 93.6 %, 90.7 %, and 85.4 % in comparison with flounder, chinook salmon, and human IGF-I, respectively. To obtain recombinant biologically active polypeptides, korean rockfish B-C-A-D domains were amplified using the PCR, then the isolated cDNA was expressed in the E. coli BL21(DE3). The recombinant KR IGF-I protein biological function was measured by stimulation of [$^3H$] thymidine incorporation, suggesting the cDNA codes for the korean rockfish proIGF-I.

• Journal of fish pathology
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• v.23 no.3
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• pp.323-334
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• 2010

Bactericidal/permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) are important components of the mammalian innate defence system against Gram-negative infections. The BPI/LBP cDNA was identified from the black rockfish ConA/PMA or LPS stimulated leukocyte cDNA library. The full-length BR-BPI/LBP cDNA was 2118 bp long and contained an open reading frame (ORF) of 1422 bp that encoded 473 amino-acid residues. The 5' UTR had a length of 57 bp, and the 3' UTR 639 bp. The molecular weight and theoretical isoelectric point (pI) values were calculated 51.4 kDa and 9.72, respectively. Compared with other known BPI or BPI/LBP peptide sequences, the most conserved regions of the black rockfish BPI/LBP peptide were found to be the BPI1 N-terminal, BPI2 C-terminal domains and a LPS binding domain. Phylogenetic analysis based on the deduced amino acid sequence revealed a homologous relationship between the BPI/LBP sequence of black rockfish and that of other teleosts. The black rockfish BPI/LBP gene was predominantly expressed in the PBLs, head kidney, trunk kidney and spleen. The expression of the black rockfish BPI/LBP molecule was induced in the peripheral blood leukocytes (PBLs) from 1 to 24 h following LPS stimulation, with a peak at 12 h post-stimulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.2
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• pp.129-137
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• 2019

This study was conducted to investigate the effects of underwater noise caused by pile driving during marine construction on fish. In this study, the three gray rockfish were released about 1 km away from the construction site of wind power generation on July 18, 2018 and traced using two acoustic telemetry techniques. The behavior of the fish was analyzed by calculating the moving distance, swimming speed and direction of the gray rockfish. In the results of the acoustic tracking using the ship, the rockfish moved about 2.11 km for about two hours at a speed of $0.28{\pm}0.14m/s$ (0.94 TL/s). The bottom depth of the trajectory of the rockfish was $1.0{\pm}0.6m$ on average. There was a significant directionality in swimming direction of the gray rockfish, and there was no significant correlation between the swimming direction and tidal current direction. Moving distance during 5 minutes (5MD) during pile driving and finishing operations between rock surface and bedrock were 0.94-0.96 times (76.0-77.0 m) and 1.81-2.73 times (146.0-219.5 m), respectively, compared with no pile driving. This study is expected to be used as a basic data of fish behavior research on underwater noise.

• 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 the Korean Society of Marine Environment & Safety
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• v.19 no.3
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• pp.241-247
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• 2013

Yellow clay dispersion has been applied to minimize fisheries impact by the red tide Cochlodinium polykrikoides blooms in Korean coasts since 1995. The present preliminary study documents the effect of yellow clay on Korean rockfish, Sebastes schlegelii, in terms of oxygen consumption rate (OCR). The OCR in the low clay suspension (0.05 and 0.23 %, w/w) showed normal level compared to the control. In contrast, the OCR for each one of three replicates in the high clay suspension (1.16 and 5.58 %, w/w) was not returned to the previous level that clay was not treated, indicating that high clay suspension (${\geq}1.16%$, w/w) might give negative effect on Korean rockfish. Overall, this result suggests that field application of clay to control Harmful Algal Blooms (HABs) may not give impact on Korean rockfish once the clay is dispersed in a low concentration (${\leq}0.23%$). In order to understand the changes of OCR in the repeated exposure to clay, it is required to do further studies on the changes of OCR when the fish is exposed to clay repeatedly after recovery in the normal seawater.

• Parasites, Hosts and Diseases
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• v.55 no.2
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• pp.219-224
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• 2017

In July 2012, philometrid nematodes were discovered in cultured rockfish (Sebastes schlegeli) in Cheonsuman (Bay), the Republic of Korea. The nematodes were detected in the epithelial tissues of the rockfish and were identified as Clavinema mariae based on morphological studies using light and scanning electron microscopy. They revealed the characteristics same as previously identified C. mariae, notably having a long body with narrow posterior half, no caudal projection, a cylindrical-shaped esophagus, a well-developed anterior bulbous part of the esophagus, cephalic papillae, and a dorsal esophageal gland. This is the first confirmation of C. mariae infection in rockfish in Korea.