• 한국수산과학회지
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• 제35권6호
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• pp.551-556
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• 2002

출산기에 임박한 조피볼락 암컷에 20mg/kg체중의 농도로 3,5, 3'-triiodo-L-thyronine $(T_{3}$)를 주사한 뒤, 출산 자어로의 호르몬 전이여부, 자어 성장과 활력을 조사하였다. 출산자어의 갑상선 호르몬을 분석한 결과,출산직후에 $T_{3}$구가 대조구 보다 높은 $T_{3}$농도를 나타냈으나, L-thyroxine $(T_{4}$)의 농도는 대조구와 유의차가 없었다. 그러나 실험기간 동안 어체내 모든 실험구의 감상선호르몬 농도는 $T_{3}$가 $T_{4}$에 비해 상대적으로 낮았고, 실험구별로는 $T_{3}$구가 대조구에 비해 높은 것을 알 수 있었다. 자어의 성장률은 대조구에 비하여 T,구에서 높았으며, 출산후 경과일수에 따라 직선적인 전장성장 경향을 나타냈다. 실험종료시 생존율은$ T_{3}$구의 자어가 대조구에 비해 높았으며, 유영활성에서도 $T_{3}$구의 자어가 대조구에 비해 유의하게 높았다. 출산직전 $T_{3}$ 모체주사는 외부영양원 섭취개시기의 자어성장 및 생리활성을 증진시키는 데 효과적인 것으로 나타났다. 이상의 연구결과로부터 출산전 모체주사를 통하여 외인성 $T_{3}$가 자어로 전이되며, 전이된 호르몬은 출산후의 자어의 초기 발달기 동안 생리적으로 긍정적인 작용을 할 것으로 추측된다.

• 한국수산과학회지
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• 제33권5호
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• pp.373-377
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• 2000

조피볼락, S. schlegeli 치어에 $estradiol-l7{\beta}\;(E_2)$와 $17{\alpha}-methyltestosterone$ (MT) 그리고 고수온을 처리하여 성분화에 미치는 영향을 조사하였다. 실험어는 출산 후 56일부터 72일까지 $E_2\;20,\;40,\;60\;{mu}g/g\;diet$ 농도로 경구투여 하였고, MT는 $20, 50{\mu}g/g diet$ 농도로 경구투여 하였다. 고수온 처리는 대조구 그리고 호르몬 처리구와 비교하여 약 $10^{\circ}C$ 이상인 $27.0{\pm}0.5^{\circ}C$로 사육하였다. 출산 후 56일까지 성분화 과정에서, 생식소는 대부분 생식원세포로 구성되어 있어 성적으로 미분화 단계였다. 그러나 출산후 128일째에, 난소는 난소강파 난소박판으로 구성되어 있고, 난원세포와 주변인기난모세포는 난소박판에 분포하고 있다. 그리고 정소는 많은 정세관으로 이루어 졌고, 이들 세관내에는 정원세포들이 무리를 지어 분포하고 있긴 또한 색소포들이 정소의 수질층과 기부에 드문드문 분포하고 있다. 성비에 있어, 대조구와 비교하였을 때 모든 $E_2$, 처리구는 더 많은 암컷이 관찰되었고, 반면에, 모든 MT 처리구와 고수온 처리구에서는 더 많은 수컷이 관찰되었다. 이러한 결과들에서, 성스테로이드 호르몬의 농도와 종류 그리고 고수온 사육이 조피볼락의 성분화 과정에 있어서 성결정에 영향을 주고 있다고 볼 수 있다.

• 한국수산학회:학술대회논문집
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• 한국수산학회 2005년도 춘계학술대회
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• pp.168-169
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• 2005

• 수산해양교육연구
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• 제24권5호
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• pp.609-615
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• 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.

• Asian-Australasian Journal of Animal Sciences
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• 제27권5호
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• pp.690-699
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• 2014

Three feeding trials were conducted to evaluate the effects of feeding rate and water temperature on growth and body composition of juvenile Korean rockfish, Sebastes schlegeli rearing at 3 different water temperatures. A total of 270 fish (each experiment) individual body weight (BW) averaging $16{\pm}0.3g$ ($mean{\pm}SD$) were fed a commercial diet for 4 wk at $16^{\circ}C$, $20^{\circ}C$, and $24^{\circ}C$. At each temperature, triplicate tanks were assigned to one of 6 feeding rates: 1.5%, 2.5%, 2.8%, 3.1%, 3.4%, and satiation (3.7% BW/d) at $16^{\circ}C$, 1.9%, 2.9%, 3.2%, 3.5%, 3.8% and satiation (4.1% BW/d) at $20^{\circ}C$ and 1.7%, 2.7%, 3.0%, 3.3%, 3.6%, and satiation (3.9% BW/d) at $24^{\circ}C$ water temperature. Weight gains of fish in satiation and 3.4% groups at $16^{\circ}C$, in satiation and 3.8% groups at $20^{\circ}C$ and in satiation and 3.6% groups at $24^{\circ}C$ were significantly higher than those of fish in the other treatments (p<0.05). A broken line regression analysis of weight gain indicated that optimum feeding rates of juvenile Korean rockfish were 3.41% at $16^{\circ}C$, 3.75% at $20^{\circ}C$ and 3.34% at $24^{\circ}C$ water temperature. Results of the present study indicate that the optimum feeding rate could be >3.1% but <3.41% at $16^{\circ}C$, >3.5% but <3.75% at $20^{\circ}C$ and >3.0% but <3.34% at $24^{\circ}C$. As we expected results suggest that fish performed better at $20^{\circ}C$ than $16^{\circ}C$ or $24^{\circ}C$ water temperature and the optimum feeding rate could be 3.1% BW/d to 3.7% BW/d in 16 g of juvenile Korean rockfish.

• Asian-Australasian Journal of Animal Sciences
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• 제27권9호
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• pp.1319-1327
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• 2014

Two feeding trials were conducted to determine the optimum feeding frequency in growing Korean rockfish, (Sebastes schlegeli) reared at the temperatures of $15^{\circ}C$ and $19^{\circ}C$. Fish averaging $92.2{\pm}0.7$ g (mean${\pm}$standard deviation [SD]) at $15.0{\pm}0.5^{\circ}C$ and $100.2{\pm}0.4g$ ($mean{\pm}SD$) at $19.0{\pm}0.5^{\circ}C$ water temperature were randomly distributed into each of 15 indoor tanks containing 250-L sea water from a semi-recirculation system. A total of five feeding frequency groups were set up in three replicates as follows: one meal in a day at 08:00 hour, two meals a day at 08:00 and 17:00 hours, three meals a day at 08:00, 14:00, and 20:00 hours, four meals a day at 08:00, 12:00, 16:00, and 20:00 hours, and one meal every 2 days at 08:00 hour. Fish were fed at the rate of 1.2% body weight (BW)/d at $15^{\circ}C$ and 1.5% BW/d at $19^{\circ}C$. At the end of 8 wks of feeding trial weight gain and specific growth rate were significantly higher at the fish fed groups of one meal a day and two meals a day at $15^{\circ}C$ and fish fed groups of 1 meal every 2 days at $19^{\circ}C$ were significantly lower than those of all other fish fed groups. Glutamic oxaloacetic transaminase and glutamic pyruvic transaminase of fish fed group at 1 meal every 2 days was significantly higher than those of all other fish fed groups in both experiments. Weight gain, specific growth rate and condition factor were gradually decreased as the feeding frequency increased. The results indicate that growing Korean rockfish 92 and 100 g perform better at $15^{\circ}C$ than $19^{\circ}C$ water temperature. As we expected, current results have indicated that a feeding frequency of 1 meal a day is optimal for the improvement of weight gain in growing Korean rockfish grown from 92 g to 133 g at $15^{\circ}C$ and 100 g to 132 g at $19^{\circ}C$ water temperature.

• 한국수산과학회지
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• 제43권3호
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• pp.262-269
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• 2010

Seventeen fish species were counted in an underwater visual census, and the most common species, Sebastes inermis and Halichoeres poecilopterus, were released. More than 60% of the released S.inermis occurred near a fish farm 5 days after release, but they moved to a distant rocky area, and decreasing numbers were seen near the farm 90 days after release. In pots, a total of 722 individuals belonging to 43 species occurred, and released S.inermis dominated with 174 individuals recaptured during the study period. The other common fish species were Stephanolepis cirrhifer and Acanthopagrus schlegeli. The percentage of recapture was 0.23%, but declined to 0.12% at 90 days after release. The potential predators of released S.inermis included Lateolabrax japonicus and Sebastes schlegeli.

• 한국수산과학회지
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• 제53권2호
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• pp.218-230
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• 2020

The single anatomical attribute that has the greatest influence on acoustic scattering from fish is the presence or absence of a swimbladder. This study examined the effect of removing the gas from the swimbladder on the broadband backscattering characteristics of six species of swimbladdered fish: striped beakperch Oplegnathus fasciatus, black scraper Thamnaconus modestus, dark-banded rockfish Sebastes inermis, goldeye rockfish Sebastes thompsoni, black rockfish Sebastes schlegeli and panther puffer Takifugu pardalis. Before and after removing the gas from the swimbladder, the species-specific, frequency-dependent backscattered echo signals from anaesthetized individuals of each fish species were measured at approximately 1° intervals spanning a 90° aspect angle range from -45° (head down) to +45° (head up) using a broadband echo sounder operating at 100-200 kHz. The relationship between the wavelength-normalized backscattering cross section (σ/λ²) and fish length (L/λ) was calculated for each species. The average σ/λ² value for the six fish species at a L/λ range of 19.79-25.85, with a mean of 22.89, was reduced by approximately 52.3% when the gas was removed.

• Fisheries and Aquatic Sciences
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• 제7권1호
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• pp.16-22
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• 2004

Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually decreased to 9L: 15D in October. It was then gradually increased to 12L:12D in January, followed by 14L:I0D in February. The water temperature was $19-20^{\circ}C$ in July. From August to October, it was from $18^{\circ}C\;to\;12^{\circ}C$. Then, it was dropped to a low of $19-11^{\circ}C$ in November to December and then gradually increased to $14-15^{\circ}C$ in February. In females, both plasma $estradiol-l7\beta\;$ (E2) and testosterone (T) levels from August to February showed a similar pattern in both the treatment and the control groups. In the treatment group, the peaks of plasma E2 and T were observed in November, and the peaks were closely correlated to histological observations. Oocytes contained many yolk globules (final vitellogenic oocytes), and oocytes at the migratory nucleus stage increased in size. Plasma levels of progesterone did not change much throughout the experimental period. However, in the control group, the peaks of E2, T, and progesterone were observed in February. These results indicate that the controlled photoperiod and water temperature accelerated sexual maturity, corresponding to the advancement of plasma E2 and T peaks by approximately 3 months. In males, plasma T levels showed a similar pattern from August to October in the treatment and control groups, though levels in the treatment group were higher than those in the control group. From histological observations, the treatment group copulated one month earlier.

• 한국수산과학회지
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• 제46권6호
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• pp.746-752
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• 2013

An 8-week feeding experiment was conducted to evaluate three types of squid Sepia esculenta liver powder (SLP) as a dietary protein source for replacement of fish meal (FM) in the juvenile black rockfish, Sebastes schlegeli. For replacement of FM, six experimental diets were formulated with 5 or 10% of either of three types (A, B, C) of SLP: SLP-$A_5$, SLP-$A_{10}$, SLP-$B_5$, SLP-$B_{10}$, SLP-$C_5$, and SLP-$C_{10}$. One of the control diets contained 100% FM as the protein source, and the other was a commercial diet (Com). Fish with an average body weight of $6.50{\pm}0.03g$ ($mean{\pm}SD$) were allocated randomly in triplicate groups of 50 to aquaria and fed the experimental diets until satiation. The weight gain (WG) and specific growth rate (SGR) of fish fed the FM, SLP-$A_5$, SLP-$A_{10}$, and SLP-$B_5$ diets were higher than those of fish fed the Com, SLP-$B_{10}$, SLP-$C_5$ and SLP-$C_{10}$ diets. No significant differences were observed in WG and SGR among the diet groups, with the exception of the SLP-$C_{10}$ diet group. The feed efficiency (FE) and protein efficiency ratio (PER) of fish fed the SLP-$A_5$, SLP-$A_{10}$, and SLP-$B_5$ diets did not differ from those fed the control diet. However, fish fed SLP-$B_{10}$ and SLP-$C_{10}$ had lower FE and PER than the fish fed the FM, commercial, SLP-$A_5$, SLP-$A_{10}$, and SLP-$B_5$ diets. Both the SLP-A and SLP-B diets, but not the SLP-C diets, replaced up to 10% and 5% of FM for juvenile black rockfish, respectively. The results of this experiment provide information that will assist in formulating an inexpensive and practical diet containing SLP for juvenile black rockfish.