• 한국수산과학회지
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• 제52권5호
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• pp.474-481
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• 2019

This study evaluated the chronic effects of $NO_3-N$ on juvenile blackhead seabream Acanthopagrus schlegelii. The experiment used six identically configured recirculating aquaculture systems (435 L), with three tanks (70 L) each. The $NO_3-N$ concentrations studied were 0 (control), 62.5, 125, 250, 500, and 1,000 mg/L $NO_3-N/L$. Thirty juvenile blackhead seabream ($18.8{\pm}2.2g$) were stocked in each tank. Growth and hematological changes were evaluated after 120 days. At the end of the experiment, the growth, survival, and cortisol levels indicated that blackhead seabream were healthy in 500 mg $NO_3-N/L$. However, insulin-like growth factor I (IGF-1) and the IGF-1 receptor were significantly lower at 250, 500, and 1,000 mg $NO_3-N/L$ than in controls (62.5 and 125 mg $NO_3-N/L$). Juveniles were likely affected at a much lower $NO_3-N$ concentration than 250 mg/L $NO_3-N/L$ in terms of IGF-1 and the IGF-1 receptor. Therefore, for the sake of long-term fish welfare, the $NO_3-N$ should be maintained at lower than 250 mg/L for blackhead seabream in recirculating aquaculture systems.

• 생명과학회지
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• 제25권1호
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• pp.16-20
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• 2015

참돔과 감성돔은 우리나라 주변에 서식하는 고유 어종으로, 참돔의 암컷과 감성돔의 수컷을 이용한 인공수정에 의하여 잡종은 생산되었으나, 자연 상태에서는 이들 간의 잡종이 보고된 바 없다. 이들 두 어종의 암수 및 타 어종을 섞어서 대형 수조에서 사육하는 과정에서 생산된 수정란을 회수하여 부화시켜 육성하는 과정에서 이들 두 종간의 잡종의 형태를 보이는 개체들이 관찰되었다. 임의로 96개체를 선택하여 두 종에 모두 적용할 수 있는 microsatellite marker를 이용하여 유전학적 분석을 실시한 결과 96개체 중 두 종의 혼합된 형태적 특징을 보이는 15개체는 참돔 암컷과 감성돔 수컷 간의 잡종으로 판명되었으며, 나머지 81개체는 감성돔 치어로 확인되었다. 사육 수조의 크기가 매우 컸으며 다른 어류들도 함께 들어 있었다는 점과, 이와 같이 유전적으로 구분되는 두 종 간의 잡종이 자연상태와 유사한 환경에서 생산되었다는 점을 고려할 때 본 연구의 결과는 자연 상태에서도 인위적인 영향이나 기후 변화에 의하여 이들의 서식지가 중복될 경우 두 종간의 잡종이 생산될 가능성이 있다는 것을 시사한다.

• 한국수산과학회지
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• 제52권3호
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• pp.268-273
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• 2019

This study evaluated acute nitrate nitrogen ($NO_3-N$) toxicity in juvenile blackhead seabream Acanthopagrus schlegelii. Seventy juveniles (Trial A, $7.1{\pm}0.6g$) and nine juveniles (Trial B, $71.3{\pm}3.5g$) per 70 L tank were exposed to $NO_3-N$ concentrations of 0, 500, 1500, 2500, 3500, and 4500 mg/L and 0, 600, 1200, 1800, 2400, and 3000 mg/L, respectively, in triplicate for 7 days. In Trial A, all fish exposed to 3500 and $4500mg\;NO_3-N/L$ died within 48 h; in Trial B, all fish exposed to $3000\;NO_3-N/L$ died after 120 h. The $96\;LC_{50}$ and $168\;LC_{50}$ were 2505 and $1806mg\;NO_3-N/L$, respectively, in Trial A, and 2663 and $2377mg\;NO_3-N/L$ in Trial B. Large juveniles were more resistant to $NO_3-N$ than small juveniles. The results of acute $NO_3-N$ toxicity studies provide important data for subsequent chronic toxicity studies.

• 한국수산과학회지
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• 제48권4호
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• pp.474-482
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• 2015

This study aims to investigate the patterns and incidence rates of morphological deformities during artificial fingerling production of blackhead seabream (BSB, Acanthopagrus schlegeli) juveniles by visual and soft X-ray observations of BSB juveniles (n=881) collected from four industrial hatcheries. Using both methods, we observed seven types of external deformity ($11.2{\pm}4.4%$) and eight types of skeletal deformity ($53.4{\pm}5.1%$). Lordosis occurred in all hatcheries with the highest frequency and the mean frequency was $13.1{\pm}4.4%$ (24.5% in total abnormal) by soft X-ray. Although they had a similar standard length (SL), juveniles with lordosis had a significantly lower condition factor and body weight than normally developed juveniles (P<0.05); normal distribution curves of histogram of body proportions, i.e., body height (BH)/head length (HL) and trunk (=SL-HL)/BH, indicated differences between normally developed juveniles and those with lordosis. In addition, 59% of juveniles with lordosis had vertebral curvature of less than $20^{\circ}$, generally at the $17^{th}$ vertebrae. It is expected that the above results will be used as basic data necessary for determining the cause of lordosis and for developing techniques to prevent this symptom in the fingering production industry of BSB juveniles.

• Journal of Species Research
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• 제8권4호
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• pp.373-379
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• 2019

Two parasitic copepods, poecilostomatoid Colobomatus mylionus Fukui, 1965 and siphonostomatoid Clavellisa chinensis ($Y{\ddot{u}}$, 1933), were reported for the first time from Korea and redescribed based on the females collected from the marine fish of Korean waters. The C. mylionus was collected from the blackhead seabream, Acanthopagrus schelegelii(Bleeker). Colobomatus mylionus had been frequently reorded from marine teleost fishes from of Eden, Newcastle, Brisbane, Yelloon, and Point Sampson. The second record was C. chinensis redescribed based on the speciemens collected from the gills of a Japanese grenadier anchovy, Coilia nasus Temminck and Schlegel. Some differences were observed between the orginal description of known specimens examined in this study, these differences do not warrant a change in the taxonomic staus of the two species. The attachment site of all two copepods reported from Korea were the cephalic sensory canals and gills.