• 한국수산과학회지
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• 제47권6호
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• pp.796-800
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• 2014

A feeding trial was conducted to investigate the growth and body composition of juvenile sea cucumber Apostichopus japonicus in integrated culture with abalone Haliotis discus hannai or rockfish Sebastes schlegeli. Triplicate groups of sea cucumber averaging $1.2{\pm}0.05g$ were cultured alone or with abalone or rockfish for 12 weeks. Survival of sea cucumber was not affected by co-culturing (P>0.05). Weight gain of sea cucumber cultured with rockfish was significantly higher than that of sea cucumber cultured alone (P<0.05), and did not differ from that of those cultured with abalone (P>0.05). These findings indicate that co-culturing sea cucumber with rockfish effectively improves the growth of sea cucumber.

• Fisheries and Aquatic Sciences
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• 제17권2호
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• pp.229-247
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• 2014

Seven feeding trials were conducted to determine the effects of feeding rate and frequency in the Korean rockfish Sebastes schlegeli at seven different water temperatures. Two feeding-rate experiments for 5-g Korean rockfish at $17^{\circ}C$ and $20^{\circ}C$; three feeding rate experiments for 16-g Korean rockfish at $16^{\circ}C$ and $24^{\circ}C$; and finally, two feeding frequency experiments for 93- and 100-g at $15^{\circ}C$ and $20^{\circ}C$ were conducted. Twenty fish averaging $5.5{\pm}0.2$ g ($mean{\pm}SD$) were randomly distributed into 18 indoor tanks containing 40-L seawater from a semi-recirculation system. Fish were fed a commercial diet for 4 weeks at water temperatures of $17^{\circ}C$ and $20^{\circ}C$. Two feeding trials were conducted to determine the optimum feeding frequency in growing Korean rockfish reared at temperatures of $15^{\circ}C$ and $19^{\circ}C$. Broken line regression analysis of weight gain (WG) indicated that the optimum feeding rates of 5-g growing Korean rockfish were 4.48% (BW/day; BW, body weight) at $17^{\circ}C$ and 4.83% (BW/day) at $20^{\circ}C$. Broken line regression analysis of WG showed optimum feeding rates of 16-g juvenile Korean rockfish of 3.41% (BW/day) at $16^{\circ}C$, 3.75% (BW/day) at $20^{\circ}C$, and 3.34% (BW/day) at $24^{\circ}C$. The biological performance, results, along with morphological indices and serological characteristics, suggest that a feeding frequency of 1 meal/day was optimal to improve WG in growing Korean rockfish grown from 93 to 133 g at a water temperature of $15^{\circ}C$, and 100 to 132 g at $19^{\circ}C$.

• 한국어병학회지
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• 제34권1호
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• pp.1-7
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• 2021

Red sea bream iridovirus (RSIV), belonging to the genus Megalocytivirus, is the predominant cause of mortality in marine fishes in Korea, including rock bream (Oplegnathus fasciatus). Rockfish (Sebastes schlegelii) are the host fish for RSIV, exhibiting no clinical signs or mortality. Cohabitation challenges, which mimicked natural transmission conditions, were performed to evaluate viral transmission between rock bream and rockfish, and to determine the pathogenicity and viral loads. In cohabitation challenge, artificially RSIV-infected rock bream were the viral donor, and healthy rockfish were the recipient. The results showed that although the donor rock bream had 95-100 % cumulative mortality (>10⁸ viral genome copies/mg of spleen 7-14 days after viral infection), the recipient rockfish did not die, even when the viral genome copies in the spleen were >10⁵ copies/mg. These results indicated asymptomatic infections. Notably, in a reverse-cohabitation challenge (artificially RSIV-infected rockfish as the viral donor and healthy rock bream as the recipient), RSIV horizontally infected from subclinical rockfish to rock bream (10⁷ viral genome copies/mg of spleen 21 days after cohabitation) with 10-20% cumulative mortality. These results suggest that an asymptomatic, infected rockfish can naturally transmit the RSIV without being sacrificed.

• 수산해양기술연구
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• 제42권1호
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• pp.30-37
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• 2006

Black rockfish and goldeye rockfish are commercially important fish species due to the increasing demand in Korea. When estimating the abundance of stocks for these species acoustically, it is of crucial importance to know the target strength(TS) to length dependence. In relation to these needs, TS measurement was conducted on black rockfish and goldeye rockfish in an acrylic salt water tank using 70kHz and 120kHz split beam echo sounders. The TS for these two species under the controlled condition was simultaneously measured with the swimming movement by DVR system and analyzed as a function of fish length(L). The results obtained are summarized as follows: The best fit regression of TS on fish length of black rockfish was TS=19.38 Log(L, cm)-70.46 ($r^2=0.71$) at 70kHz and TS=22.39 Log(L, cm)-70.40 ($r^2=0.64$) at 120kHz and in the standard form TS=20 Log(L, cm)-71.29 ($r^2 = 0.70$) at 70kHz and TS=20 Log(L, cm)-66.88 ($r^2=0.57$) at 120kHz. The best fit regression of TS on fish length of goldeye rockfish was TS=17.10 Log(L, cm)-68.28 ($r^2=0.37$) at 70kHz and TS=24.39 Log(L, cm)-73.74 ($r^2=0.59$) at 120kHz and in the standard form TS=20 Log(L, cm)-72.03 ($r^2=0.32$) at 70kHz and TS=20 Log(L, cm)-67.68 ($r^2=0.64$) at 120kHz. An empirical model for fish TS(dB) averaged over the dorsal aspect of 115 fishes of black rockfish and goldeye rockfish and which spans the fish length(L, m) to wavelength($\lambda$, m) ratio between 8 and 30 was derived : TS=34.12 Log(L)-14.12 Log($\lambda$)-23.83, ($r^2=0.90$).

• 한국수산과학회지
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• 제45권6호
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• pp.594-599
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• 2012

The objective of this study was to determine the processing conditions for salt dried rockfish Sebastes schlegeli by sun drying and cold-air drying, as measured by alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activity. We processed salt dried rockfish samples. The salinity of rockfish samples was within 1% following salting with 25% salt brine for 3 h. The moisture content of salt dried rockfish was found to reduce linearly from 70.12 to 39.5 g/100 g over the same time interval. The water activities of salt dried rockfish by sun and cold-air drying were 0.94 and 0.87, respectively, after three days of drying. Acid values (AV) were 10.71 and 5.96 mg KOH/g, respectively, after the three day drying period. The ADH activity in a water extract from salt dried rockfish following sun and cold-air drying for 24 h was 228.5% and 226.1% at 13.3 mg/mL, respectively, and was higher than that when drying lasted for 48 and 72 h. The ALDH activity was not affected but both ADH and ALDH activity tended to decrease as the drying time increased from 24 to 72 h. The conditions of processing for the best quality of salt dried rockfish were determined to be drying with a cold-air system for 24 h. These results indicated that water extracts from salt dried rockfish have valuable biological attributes owing to the metabolizing of alcohol and can provide useful information for the design of drying systems for salt dried rockfish.

• 한국양식학회지
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• 제11권4호
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• pp.429-435
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• 1998

조피볼락 초기 사육시 발생하는 대량 폐사 원인의 하나로 수질악화를 들 수가 있다. 수질악화의 주요원인이 되는 어류의 주요대사물인 암모니아에 대한 조피볼락의 내성을 참돔과 비교, 분석하였다. 사육수조 내에 통기를 시키지 않을 경우 산소 부족에서 오는 스트레스로 큰 어체가 작은 어체에 비해 암모니아 독성에 대한 내성이 강한 것으로 나타났다. 조피볼락의 경우, 용존산소량이 높을 때 (통기를 시킬 때), 6 시간이나 96 시간에서의 $NH_45^+$의 반수치사농도가 용존산소량이 낮을 때 (통기를 시키지 않을 때)보다 높아서 수중의 용존산소량이 암모니아 독성을 완화시킨다는 것을 보였다. 또한, 조피볼락과 참돔의 96 시간에서의 $NH_4^+$ 와 비이온화된 $NH_3$ 의 반수치사농도 결과를 비교해 볼 때, 조피볼락은 참돔에 비해 암모니아에 대한 내성이 약한 것으로 나타났다.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2003년도 추계학술발표대회 논문요약집
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• pp.70-70
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• 2003

This study was conducted to determine the effects of the dietary microbial phytase (P) supplementation on growth performance and bioavailability of phosphorus in juvenile olive flounder, Paralichthys olivaceus and juvenile Korean rockfish, Sebastes schlegeli fed soybean meal-based diets. Nine experimental diets were formulated to be isonitrogenous and isocalolic to contain 50.0%crude protein (CP) and 16.7kJ, 48.6% crude protein (CP) and 16.0kJ available energy/g without the dietary phytase supplementation for olive flounder and Korean rockfish, respectively : 100% fish meal (FM); 70% FM ＋ 30% soybean meal (SM); 70% FM ＋ 30% SM ＋ Phytase(P) 1000U/kg diet; 70% FM ＋ 30% SM ＋ P 2000U/kg diet; 70% FM ＋ 30% SM with phytase-treated (Ptre) P 1000U/kg diet; 60% FM ＋ 40% SM; 60% FM ＋ 40% SM ＋ P 1000U/kg diet; 60% FM ＋ 40% SM ＋ P 2000U/kg diet; 60% PM ＋ 40% SM with Ptre P 1000U/kg diet. After two weeks of the conditioning period, triplicate groups of 25 fish initially averaging 6.15$\pm$0.04g, was randomly distributed into the aquarium for olive flounder, and 20 fish initially averaging 7.25$\pm$0.04g was randomly distributed into the aquarium for Korean rockfish. After 8 weeks feeding trials, there was no significant difference on weight gain fish fed between 100% FM and 70% FM＋30%SM with Ptre P 1000U in olive flounder and Korean rockfish. Apparent phosphorus digestibility fish fed phytase supplemental diets were significantly higher than those of fish fed phytase non-supplemental diets in olive flounder and Korean rockfish. Therefore, these results indicated that pre-treated soybean meal with phytase 1000U could replace fishmeal up to 30% for the maximum growth of juvenile olive flounder and Korean rockfish. Phytase supplementation could improve apparent digestibility of phosphorus in olive flounder and Korean rockfish fed soybean meal based diets.

• 한국수산과학회지
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• 제48권5호
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• pp.731-738
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• 2015

Nematode infection in the epithelial tissue of cultured rockfish Sebastes schlegeli was first reported in 2012. Since then, nematode infections have caused serious economic losses in rockfish aquaculture on the west coast of Korea. Taxonomic and life cycle information for this parasite are currently unknown. In this study, 18S rRNA and cytochrome c oxidase subunit I (COI) genes were used for molecular identification and polymerase chain reaction (PCR) to detect the invisible stages of this parasite. Nucleotide sequences of the 18S rRNA of the rockfish nematode showed 98% identity with that of Philometra morii. Therefore, this rockfish nematode was classified to the Philometridae family. However, we could not identify it to genus level using 18S rRNA. Its COI nucleotide sequences shared 85% and 82% identities with those of Bursaphelenchus sinensis and Philometra overstreeti, respectively. In addition, two gene-specific primer sets were designed based on the 18S rRNA gene to detect the intermediate host and nematode larvae. These primers were specific to this rockfish nematode without cross-reacting to other pathogens. The detection limit of the PCR assay using these primers was 1,000 copies of nematoda plasmid DNA. Therefore, the PCR assay described here is suitable for the detection of nematode DNA within rockfish. In addition, this PCR assay could be used to detect nematode larvae and the intermediate host.

• 한국발생생물학회지:발생과생식
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• 제19권2호
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• pp.85-96
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• 2015

Measurements of closely related sets of classical and truss dimensions were analyzed to discriminate species of scorpaenidae including the dark banded rockfish, Sebastes inermis, the black rockfish, S. schlegeli, and gobioninae including the striped shiner, Pungtungia herzi, and the slender shiner, Pseudopungtungia tenuicorpa. The measurements of the dimensions were arc sin square root transformed, and compared as a function of the standard length of each species for statistical analysis. For values of the classical dimensions of the rockfish, 6 were greater for the dark banded rockfish than for the black rockfish, 1 value was smaller for the former, and for 2 values there was no statistically significant difference (P > 0.05). For values of the classical dimensions of the shiners, 9 values were greater for the striped shiner than for the slender shiner, 2 values were smaller for the former, and for 1 value there was no statistically significant difference (P > 0.01). For values of the truss dimensions of the rockfish, 6 were greater for the dark banded rockfish than for the black rockfish, 1 was smaller for the former, and for 4 values there was no statistically significant difference (P > 0.05). For values of the truss dimensions of the shiners, 13 values were greater for the striped shiner than for the slender shiner, 3 values were smaller for the former, and for 6 values there was no statistically significant difference (P > 0.01). The dimension sets used in this study may be useful as taxonomic indicators for discriminating among fish species in Korea.

• 한국양식학회지
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• 제11권4호
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• pp.437-447
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• 1998

조피볼락 종묘생산시 발생하는 대량폐사를 막기 위하여 자어의 다양한 먹이생물을 공급하여 성장을 비교하였고 여러 가지 방법으로 먹이생물을 영양강화시켜 공급하여 그에 따른 조피볼락 자어의 생존율과 성장률을 비교하였다. 성게 유생은 쉽게 구할 수 있으나 조피볼락 자어의 생존율을 저하시켰고 유생의 지방산 분석 결과를 볼 때 그다지 적합한 먹이로 생각되지 않는다. Rotifer나 Artemia nauplii를 단독으로 조피볼락의 자어를 먹이로 공급하는 것보다 혼합공급하는 것이 더 효과저거인 것으로 나타났다. 그리고 rotifer나 Artemia nauplii를 ${\omega}$-yeast, Spirulina platensis나 Super Selco로 영양강화시킨후에 먹이로 공급할 경우 자어의 생존율이나 성장률에서 많은 개선을 보였다. Rotifer를 Super Selco로 영양강화를 시켰을 경우 $\omega$-yeast로 영양강화를 시킨 경우보다 높은 생존율과 성장률의 결과를 보였다. 산출 후 10일 경에 대량폐사가 발생하였으며 초기에는 rotifer가 자어의 먹이로 우수한 것으로 나타났으나 10일 경 이후부터는 Artemia nauplii가 우수한 먹이로 판단된다. 그러나 rotifer와 Artemia nauplii 혼합 공급하였을 경우 rotifer나 Artemia nauplii를 단독 공급하는 경우보다 우수한 결과를 보였다.