• Fisheries and Aquatic Sciences
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• 제21권1호
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• pp.2.1-2.8
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• 2018

This study evaluated hemato-histological changes of black porgy in recirculating aquaculture systems (RAS) with three different ozone doses (no ozone, 20 g, and $40g\;ozone/kg\;feed\;day^{-1}$). During the 44-day study, black porgy did not show significant behavior changes or mortalities in both the ozonated systems displaying average total residual oxidants concentrations of 0.12 and 0.25 mg/L. There were no differences in growth and blood parameters among the systems. However, histological alterations on gills and livers were observed in both the treatment systems. In the higher ozone dose, signs of cellular damage were more apparent. Although the ozone doses did not manifest a serious adverse effect on growth and hematological observations in this short-term study, an ozone dose should not exceed $20g\;ozone/kg\;feed\;day^{-1}$ for black porgy based on the histological result. In order to use ozone in a seawater RAS, further studies will be needed to evaluate long-term effects of total residual oxidants.

• 한국양식학회지
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• 제19권1호
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• pp.14-18
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• 2006

해산어류인 감성돔의 담수사육에 따른 어육을 평가하기 위하여 근육의 경도와 강도를 조사하였으며, 설문조사를 통한 어육의 외관, 질감, 맛 및 냄새를 분석하였다. 또한 수익성분석을 위해 치어 및 육성어를 10개월간 양식하여 각각의 순수익(률)을 산출하였다. 담수사육 감성돔 근육의 경도 및 강도는 각각 $9210{\pm}1215g/cm^2,\;30693{\pm}6355g/cm^2$로 해수사육의 $9987{\pm}1893g/cm^2,\;31931{\pm}6549g/cm^2$보다 다소 낮았으나 유의한 차이는 없었다. 또한 설문조사한 결과, 어육의 외관, 질감, 맛 및 냄새에서도 담수 및 해수사육한 감성돔사이에 차이가 없는 것으로 나타났다. 감성돔 치어 및 육성어를 담수에서 10개월간 양식하였을 때 순수익(률)은 각각 24,000,000원(30.0%), 53,870,000원(36.9%)으로 나타났다.

• 한국수산과학회지
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• 제43권5호
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• pp.474-481
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• 2010

The sperm collection time, sex steroid hormones, and gonadal development of protandrous black porgy, Acanthopagrus schlegeli, acclimated in freshwater for more than 2 years were investigated to evaluate its reproductive capability. The gonadal development of black porgy reared in seawater and freshwater could each be classified into four successive stages. For black porgy reared in seawater (BSW) as the control, these were the growing (December to February), mature (February to March), spent (March to June), and degeneration and resting (July to December) stages; for black porgy reared in freshwater (BFW), these were the growing (November to January), mature (January to February), spent (February to May), degeneration and resting (June to November) stages. In both BSW and BFW, the plasma cortisol levels were the highest in March. The plasma testosterone (T) levels of BSW and BFW were the highest in March and February, respectively. The plasma estradiol-$17{\beta}$ ($E_2$) levels did not differ significantly between BSW and BFW. The 11-ketotestosterone (11-KT) levels in the plasma of BSW and BFW were the highest in April. Sperm was collectible from March to June in BSW and from February to May in BFW. The results indicated that the gonadal maturation of BFW was about 1 month faster than that of BSW.

• Animal cells and systems
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• 제13권4호
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• pp.439-445
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• 2009

Cytochrome P450 aromatase (P450arom) catalyzes the conversion of androgens to estrogens and plays an important role in reproduction and development in vertebrates. We investigated the expression patterns of ovarian P450arom (P450aromA) and brain P450arom (P450aromB) mRNA during sex change in black porgy. Maturity was divided into seven stages from male to female (immature testis, mature testis, testicular portion of mostly testis, ovarian portion of mostly testis, testicular portion of mostly ovary, ovarian portion of mostly ovary, and mature ovary). P450aromA expression was significantly higher in the ovarian portion of mostly-ovarian stage fish, and P450aromB expression was highest in the brain of black porgy with mostly-ovarian gonads. Histology showed that testicular tissues were disintegrated with the development of ovarian tissue associated with an increase in the expression of the two P450arom mRNAs during sex change. Interestingly, among various tissues, P450aromA was only expressed in the ovary, and P450aromB was only expressed in the brain. To understand the role of gonadotropin-releasing hormone (GnRH) and estradiol ($E_2$), we injected exogenous hormone (GnRH analogue [GnRHa] and $E_2$) into immature black porgy. In the GnRHa group, expression of the two P450arom genes decreased 12 h after injection, and expression of the two P450arom genes were significantly higher at 6 dafter $E_2$ injection. These results provide useful baseline knowledge on the mechanism of natural sex change in black porgy.

• 한국양식학회지
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• 제19권3호
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• pp.149-156
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• 2006

본 연구에서는 담수 및 해수사육 감성돔을 대상으로 $T_3$가 처리된 사료(10 mg/kg사료)를 90일간 공급하면서 어체의 스트레스, 삼투압조절 및 성장을 조사하였다. 혈장 $T_3$ 농도는 60일째에 FN, FT이 SN, ST에 비해 낮았으며, 또한 FN은 FT보다 유의하게 낮았다. 혈장 cortisol은 60일째를 제외하고는 실험구 사이에서 차이가 없었다 60일째에 FT $(21.0{\pm}3.3ng/ml)$는 $FN(5.1{\pm}1.4ng/ml)$보다 4배정도 높았으며, 또한 유의한 차이는 인정되지 않았지만 ST가 SN에 비해 다소 높은 것으로 나타났다. FN, FT의 혈장 glucose는 실험기간동안 SN, ST에 비해 낮은 경향을 보였으나, 담수 및 해수사육 감성돔에서 호르몬 처리에 의한 차이는 나타나지 않았다. 해수사육 감성돔의 AST 및 ALT는 실험기간동안 차이가 없었으나, 실험개시시 FN, FT의 AST및 ALT는 SN, ST보다 높았다. 또한 FN, FT의 AST의 해수수준으로 회복은 각각 실험종료시와 30일째에 해수수준으로 나타나 호르몬을 처리한 FT가 더 빨랐다. 그러나, 담수 및 해수사육 감성돔의 삼투압조절 향상 및 성장촉진을 위한 외인성 $T_3$ 공급 효과는 나타나지 않았다.

• 수산해양기술연구
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• 제48권2호
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• pp.137-146
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• 2012

Black porgy and fat greenling are commercially important fish species due to the continuously increasing demand in Korea. When estimating acoustically the fish length by a fish sizing echo sounder, it is of crucial importance to know the target strength (TS) to length dependence. In relation to these needs, the target strength experiments for live fishes were conducted in an acrylic salt water tank using two split-beam echo sounders operating at 70 and 120kHz. The target strength under well-controlled laboratory conditions was simultaneously measured with the swimming movement by digital video recording (DVR) system and analyzed as a function of fish length (L) and frequency (or wavelength ${\lambda}$). Equations of the form TS-alog (L)+blog (1)+c were derived for their TS-length dependence. The best fit regression of TS on fork length for black porgy was TS=20.62 log (L, m)-0.62 log (${\lambda}$, m)-30.68 ($r^2$=0.77). The best fit regression of TS on fork length for fat greenling was TS=12.06 log (L, m)-5.85 log (${\lambda}$, m)-22.15 ($r^2$=0.44).

• 한국양식학회지
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• 제22권1호
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• pp.122-125
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• 2009

Salinity tolerance on survival rate of 2, 4 and 6-week-old larvae and juvenile of black porgy Acanthopagrus schlegeli was investigated at 0, 7.5, 15, 22.5 and 30 psu for 21 days. In the 2 and 4-week-old larvae and juvenile (TL: 1.23 and 1.72 cm) were all died within 12 and 26 hours after to the 0 psu transfer, respectively. However, survival rate of other experimental group (7.5, 15, 22.5 and 30 psu) was significantly difference in the range between 27.3% and 95% (P<0.05). However survival rate of 6-weeks-old juvenile (TL: 2.83 cm) were over 99.0% during experimental periods and they appeared in good health. There was no significant difference in survival those reared to the salinities of all experimental groups (P>0.05). The present study suggests that the freshwater and saline groundwater of low salinity could be used to grow early juveniles of black porgy and it may be possible to culture in freshwater.

• 수산해양교육연구
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• 제24권3호
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• pp.387-394
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• 2012

Fertilization rates were over 90% when sperm from black porgy Acanthopagrus schlegelii acclimated and raised in freshwater and black porgy raised in seawater were fertilized with eggs from female black porgy raised in seawater, although cryopreserved sperm were significantly lower in fertilization rates than non-cryopreserved sperm. From the observations of embryos development at different salinities (0, 10, 20 and 32 psu) within 3 hours upon fertilization (16 cell stage), all were dead at 0 psu. However, the development process and speed at 10 and 20 psu were the same as at 32 psu. But, many developing embryos were egg envelope injury at low-salinities of 10 and 20 psu unlike at 32 psu. This is attributable to osmotic shock. Hatching rate of embryos at 32 psu was 60% or so, whereas low as 5% or less were successfully hatched at 10 and 20 psu, implying that osmotic shock could be responsible for the failure of embryo development.

• 수산해양기술연구
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• 제28권1호
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• pp.1-9
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• 1992

The author has examined the response of sting fish, Sebastes inermis and black porgy, Acanthopagrus schlegelii to the attraction lamps(1 W) line in an experimental water tank(550 L$\times$ 58 W $\times$ 73H cm). Attraction lamp was set up at intervals of 55 cm for each section. The frequency rate was investigated at the illuminated section in accordance with the intervals of lighting on and putting out that was 1, 3 and 5 minutes under two conditions of light stimulus. The results are as follows: 1. Frequency rate at the last section when each of the attraction lamps was gradually switched on and off: (1) Sting fish was 27.2 % in case of 3 minutes interval, and 17.4 % in 1 minutes interval, and 15.8 % in 5 minutes interval. (2) Black porgy was 28.5 % in case of 5 minutes interval, and 25.8 % in 3 minutes interval, and 12.0 % in 1 minutes interval. 2. Distribution of fish at the illuminated section when each of the attraction lamps was gradually switched off after they were switched on all at once: (1) Sting fish was much gathered in the section adjacent to the extinguished section under the condition of 1 and 3 minutes interval, and not regular trend under 5 minutes interval. (2) Black porgy was much gathered last section under the condition of 1 and 3 minutes interval, and almost evenly distributed under 5 minutes interval. 3. Each of the attraction lamps was gradually switched off after they were switched on all at once, and only the last one was on: (1) The frequency rate of Sting fish was 27.2 % in case of 5 minutes interval, and 16.0 % in 1 minute interval, and 8.0 % in 3 minutes interval. (2) The frequency rate of Black porgy was 10.7 % in case of 1 minute interval, and 8.9 % in 3 minutes interval, and 0.8 % in 5 minutes interval.

• Fisheries and Aquatic Sciences
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• 제8권3호
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• pp.177-181
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• 2005

Fishing selectivity is determined by the level of voluntary escaping behavior in accordance with decision-making based on the relationship between fish size and mesh size. This study examined movement during the swimming behavior of black porgy in a trawl's towing cod-end and analyzed the movement components such as swimming speed, angular velocity of turning, and distance to the net over time. Most of the observed fish exhibited an optomotor response, maintaining position and swimming speed without changing direction. Others exhibited erratic or 'panic' behavior with sudden changes in swimming speed and direction. The latter behavior involved very irregular and aperiodic variations in swimming speed and angular velocity, termed 'chaotic behavior.' Thus, the results of this study can be applied to a chaotic behavior model as a time series of swimming movements in the towing cod-end for the fishing selectivity.